ES2580082T3 - Monitoring system - Google Patents

Abstract

An impedance measuring device, for carrying out impedance measurements on a subject, including the device: a) an input device (22), to receive input commands from an operator, b) a first processing system ( 10), coupled to the input device, and c) a second processing system (17) coupled to the first processing system, in which the second processing system (17): (i) applies one or more signals to the subject through of electrodes (13, 14); (ii) receives an indication of the one or more signals applied to the subject through electrodes (15, 16); (iii) receives an indication of one or more measurement signals through the subject; (iv) carries out at least a preliminary process of the indications to thereby determine the impedance values, characterized in that d) the first processing system (10) includes a memory (21) for storing profiles representing procedures of predetermined impedance measurement, in which the first processing system (10): i) determines one of the impedance measurement procedures according to the input commands received by an operator's input device (22); and, ii) selects instructions corresponding to the determined impedance measurement procedure; and e) the second processing system (17) includes a programmable module (36) controlled by the selected instructions, in which the second processing system (17): (v) generates, using the instructions, the control signals that are used to apply one or more signals that implement the determined impedance measurement procedure to the subject; and (iv) perform, using the instructions, at least preliminary processing of the indications to allow the impedance values to be determined in this way.

Description

5

10

fifteen

twenty

25

30

35

40

Four. Five

fifty

55

60

65

DESCRIPTION

Monitoring system Background of the invention

The present invention relates to a method and an apparatus for monitoring biological parameters and, in particular, to an apparatus for making impedance measurements.

Description of the prior art

The reference herein to any previous publication (or information derived from it), or for any matter that is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that the previous publication (or information derived from it) or the known matter is part of the common general knowledge in the field of activity referred to in this report.

One of the existing techniques for the determination of biological parameters related to a subject, such as cardiac function, involves the use of bioelectrical impedance. This involves measuring the electrical impedance of a subject's body using a series of electrodes placed on the surface of the skin. Changes in electrical impedance on the surface of the body are used to determine parameters, such as changes in fluid levels, associated with the cardiac cycle or edema.

Consequently, complex signal processing is required to ensure measurements that can be interpreted.

Typically the devices to achieve this use hardware configurations as they are specific to the application. As a result, devices can normally only be used in a limited range of circumstances.

EP 1 219 937 discloses a postpartum support apparatus having a main unit, for carrying out impedance measurements, and a control unit. The control unit sends a command to start the impedance measurement to the main unit, and allows the user to enter data or consult the information on a screen. The main unit starts measuring the impedance in response to a measurement command. The body fat rate is determined using a standard impedance calculation.

Summary of the present invention

In a first broad form, the present invention provides an impedance measurement apparatus, for performing impedance measurements on a subject, including the apparatus:

a) an input device to receive input commands from an operator

b) a first processing system, coupled to the input device, and

c) a second processing system coupled to the first processing system, in which the second processing system:

(i) apply one or more signals in the matter;

(ii) receives an indication of the one or more signals applied to the subject;

(iii) receives an indication of one or more measurement signals across the subject;

(iv) performs at least a preliminary process of the indications to thereby allow the impedance values to be determined,

characterized by that

d) the first processing system includes a profile storage warehouse representing the predetermined impedance measurement procedures, in which the first processing system:

i) determines one of the impedance measurement procedures in accordance with the input commands received by an operator's input device; Y,

ii) select the instructions corresponding to the measurement procedure of the determined impedance; Y

e) the second processing system includes a programmable module controlled by the selected instructions, in which the second processing system:

(v) generates, using the instructions, the control signals that are used to apply one or more application signals the measurement procedure of the determined impedance to the subject; Y

(vi) performs, following the instructions, at least, the preliminary processing of the indications to thereby allow the impedance values to be determined.

5

10

fifteen

twenty

25

30

35

40

Four. Five

fifty

55

60

65

Typically, the method includes transferring the instructions from the first processing system to the second processing system.

Typically, the method includes the selection of instructions using configuration data.

Typically, the method includes receiving the configuration data of a remote processing system. Typically, the instructions are in the form of at least one of:

a) firmware; Y,

b) integrated systems.

Typically, the second processing system is an FPGA.

Typically, the control signals represent a sequence of predetermined electrical signals, the sequence being dependent on the type of impedance measurement selected.

Typically, the apparatus includes:

a) a current ADC for:

i) receive the signals of a current circuit; Y,

ii) provide the indication of the one or more signals applied to the subject for the second processing system; Y,

b) a tension ADC for:

i) receive signals from a voltage circuit; Y,

ii) provide the indication of the one or more signals measured from the subject to the second processing system.

Typically, the apparatus includes at least one buffer circuit for:

a) receive the voltage signals from a voltage electrode;

b) filter and amplify the voltage signals; Y,

c) transfer the filtered and amplified voltage signals to the ADC voltage through a differential amplifier. Typically, the apparatus includes a current source circuit for:

a) receive one or more control signals;

b) filter and amplify the control signals to thereby generate one or more current signals;

c) apply the current signals to a current electrode; Y,

d) transfer an indication of the signals applied to the current ADC.

Typically, the apparatus includes a control signal DAC for:

a) receive the control signals of the second processing system; Y,

b) provide analog control signals to a current circuit to thereby cause one or more current signals to be applied to the matter in accordance with the control signals.

Typically, the second processing system is formed of first and second parts of the processing system, the first and second portions of the processing system being electrically insulated to thereby electrically isolate the subject from the first processing system.

Typically, the apparatus includes:

a) a measuring device includes at least the first processing system; Y,

b) one or more units of subjects, each unit of subject including at least part of the second processing system.

Typically, the apparatus includes at least two current electrodes for the application of current signals to the subject, and a switch connected to the current electrodes for the discharge of the subject before the measurement of the induced voltage.

Typically, the apparatus includes a housing that has:

5

10

fifteen

twenty

25

30

35

40

Four. Five

fifty

55

60

65

a) a screen;

b) a first circuit board for mounting at least one of the processing systems;

c) a second circuit board for mounting at least one of an ADC and a dAC; Y,

d) a third circuit board for mounting a power supply.

Normally the housing is formed by at least one of a mu-metal and aluminum with magnesium added, to thereby provide an electric / magnetic shield.

Typically, the apparatus includes multiple channels, each channel being for carrying out impedance measurements using a respective set of electrodes.

Typically, the device is for:

a) the determination of an electrode identifier associated with at least one electrode provided in the subject;

b) determine, using the electrode identifier, a position electrode indicative of the position of the at least one electrode on the subject; Y,

c) perform at least one impedance measurement using the electrode position.

Typically, the device is for:

a) the determination of a parameter associated with at least one electrode conductor; Y,

b) have at least one measurement of the impedance made by the determined parameter.

Typically, the device is for:

a) receive configuration data, the configuration data being indicative of at least one feature;

b) determine, using the configuration data, the instructions representing at least one characteristic; Y,

c) make that, using the instructions, at least one of:

i) perform at least one impedance measurement; Y,

ii) analyze at least one measurement of impedance.

Typically, the device is for:

a) have a first signal applied to the subject;

b) determine at least one parameter relative to at least a second measurement signal across the subject;

c) compare the at least one parameter with at least one threshold; Y,

d) based on the results of the comparison, selectively repeat steps (a) to (d) using a first signal that has a greater magnitude.

In a second broad form, the present invention provides a method for measuring impedance measurements in a subject, including the method:

a) receive input commands from an operator

b) use a second processing system coupled to a first processing system, to apply one or more signals to the subject;

c) by means of the second processing system receive an indication of the one or more signals applied to the subject;

d) use the second processing system to receive an indication of one or more measurement signals through the subject;

e) by means of the second processing system, carry out at least preliminary processing of the first and second data to thereby allow the impedance values to be determined;

characterized in that the method includes:

f) using the first processing system to determine a measurement procedure of the impedance of a profile storage warehouse representing the predetermined impedance measurement procedures, in accordance with the input commands received; Y,

g) using the first processing system, select the instructions corresponding to the measurement procedure of the determined impedance;

h) by means of the second processing system generate, by means of the instructions, the control signals that are used to apply one or more signals of execution of the measurement procedure of the determined impedance to the subject; and

i) by means of the second processing system, carry out, following the instructions, at least the preliminary processing of the indications to thereby allow the impedance values to be determined.

5

10

fifteen

twenty

25

30

35

40

Four. Five

fifty

55

60

65

The report describes a method of diagnosing the conditions in a subject, including the method, in a processing system:

i) using a first processing system to: determine an impedance measurement procedure; and, the selection of instructions corresponding to the measurement procedure; Y,

ii) using a second processing system for: the generation, using the instructions, of control signals, the control signals are used to apply one or more signals to the subject; receive an indication of the one or more signals applied to the subject; receive an indication of one or more measurement signals through the subject; perform, using the instructions, at least the preliminary processing of the first and second data to thereby allow the impedance values to be determined.

The report describes an apparatus for connecting a measuring device to an electrode, including the device:

a) a housing that has a connector for coupling the housing to an electrode; Y,

b) a circuit mounted in the housing, the circuit being electrically coupled to the electrode using the connector, and being coupled to a conductor, the circuit being at least one of:

generate predetermined electrical signals in accordance with the control signals received from the measuring device; provide an indication of the electrical signals applied to the electrode; Y,

provide an indication of the electrical signals measured at the electrode.

Typically, the circuit is provided on a circuit board that has an electrical contact, and in which the connector uses at least a portion of the electrode in contact with the electrical contact. Normally, the connector includes a skewed arm.

Typically, the circuit includes an intermediate memory circuit to: detect voltage signals on the electrode; filter and amplify the voltage signals; and, transfer the filtered and amplified voltage signals with the measuring device.

Typically, the circuit includes a current source circuit to: receive one or more control signals; filter and amplify the control signals to thereby generate one or more current signals; apply the current signals to the electrode pad; and, transfer an indication of the signals applied to the measuring device.

Normally, the apparatus further comprises an electrode, the electrode including: an electrode substrate; and a conductive material to electrically couple the electrode to the subject.

Typically, the electrode substrate is electrically conductive, and in which in use of the connector it couples the circuit to the electrode substrate.

Typically, the housing includes curved edges.

Typically, the housing is formed of a material that, at least one of: has a low coefficient of friction; And, it is elastic.

The memory describes a method for measuring impedance in a subject, including the method, in a processing system: determining an encoded value associated with at least one electrode conductor; and causing at least one impedance measurement to be made using the encoded value.

Typically, the encoded value is used for calibration. Typically, the encoded value is determined from a resistance value. Typically, the coded value is indicative of a driver's identity.

Typically, the method includes, in the processing system, the control of the current applied to the subject using the determined resistance.

Typically, the encoded value is a conductor identifier, and in which the method includes, in the processing system: determining, using the conductor identifier, an impedance measurement procedure; and, by having the measurement procedure of the impedance decided be carried out.

Typically, the method includes, in the processing system: comparing the determined identity to one or more predetermined identities; and, the determination of the subject's impedance in response to a successful comparison.

Typically, the method includes, in the processing system: determining the conductor identifier associated with the at least one electrode conductor; determine, using the driver identifier, a driver use; compare driver use to a threshold; and, according to the results of the comparison, at least one of: generate an alert; finalize the impedance measurement procedure; and, perform an impedance measurement procedure.

5

10

fifteen

twenty

25

30

35

40

Four. Five

fifty

55

60

65

Typically, the method includes, in the processing system, at least one of: processing measured electrical signals of the subject to thereby determine one or more impedance values; and, the processing of certain impedance values.

Typically, the encoded value is stored in a warehouse.

The memory describes an apparatus for performing impedance measurements on a subject, including the apparatus: at least one conductor for connection to the electrodes coupled to the subject, the at least one conductor including a coded value; and, a processing system coupled to the at least one advantage of: determining the encoded value; and causing at least one measurement of the impedance to be carried out by means of the encoded value.

The report describes a method for measuring impedance in a subject, including the method, in a processing system:

a) determining an electrode identifier associated with at least one electrode provided in the subject;

b) determine, using the electrode identifier, a position electrode indicative of the position of the at least one electrode on the subject; Y,

c) have at least one impedance measurement made using the electrode position.

Typically, the measurement of impedance is carried out using at least four electrodes, each with a respective identifier, and in which the method includes, in the processing system:

a) determine an electrode identifier for each electrode;

b) determine, using each electrode identifier, an electrode position for each electrode; Y,

c) perform at least one impedance measurement using the electrode positions.

Typically, the method includes, in the processing system: having the signals applied to at least two of the electrodes according to the positions of the determined electrodes; and, having the signals measured from at least two of the electrodes according to the determined positions of the electrodes.

Typically, the method includes, in the processing system, determining the electrode identifier for an electrode by selectively measuring the conductivity between one or more contacts provided on the electrode.

Normally, the processing system is coupled to a signal generator and a sensor, and in which the method includes, in the processing system:

a) selectively interconnect the signal generator and at least two electrode cables, to thereby allow the signals to be applied to the subject; and,

b) selectively interconnect the sensor at least two electrode cables to thereby allow a signal to be measured from the subject.

Typically, the method includes, in the processing system, controlling a multiplexer to selectively interconnect the cables and at least one of the signal generator and the sensor.

Typically, the at least one electrode includes visual indications indicative of the position of the at least one electrode on the subject.

The memory describes an apparatus for performing impedance measurements on a subject, the apparatus including a processing system for:

a) determining an electrode identifier associated with at least one electrode provided in the subject;

b) determine, using the electrode identifier, a position electrode indicative of the position of the at least one electrode on the subject; Y,

c) have at least one impedance measurement performed using the electrode position.

The memory describes a method for configuring a measuring device to measure the impedance of a subject, including the method, in a processing system: receiving configuration data, the configuration data being indicative of at least one characteristic; determine, using the configuration data, the instructions that represent the at least one characteristic; and, do that, at least in part using the instructions, at least one of: impedance measurements to be performed; and, the analysis of the impedance measurements.

Typically the configuration data includes the instructions.

Typically, the method includes, in the processing system: determining an indication of the at least one

5

10

fifteen

twenty

25

30

35

40

Four. Five

fifty

55

60

65

feature using configuration data; and, determine the instructions using the indication of the at least one characteristic.

Typically, the method includes, in the processing system, decrypting the received configuration data. ^ Typically, the method includes, in the processing system:

a) determine a device identifier associated with the measuring device;

b) determine, using the device identifier, a key; Y,

c) decrypt the configuration data received using the key.

Typically, the processing system includes the first and second processing systems, and in which the method includes:

a) in the first processing system, select the instructions using the configuration data; Y,

b) in the second processing system, generate the control signals that use the selected instructions.

Typically, the method includes, in the first processing system, at least one of:

a) transfer the instructions for the second processing system; Y,

b) make the second processing system access the instructions of a warehouse.

Typically, the method includes, in the processing system, receiving configuration data from at least one of an information system and a communications network.

Typically, the method includes, in the processing system:

a) determine if a feature selected by a user is available;

b) if the feature is not available, determine if the user wishes to activate the function; Y,

c) if the user wishes to enable the feature, causing the configuration data to be received.

Typically, the method includes, in the processing system:

a) have the user provide a payment to a device provider; Y,

b) receive the configuration data in response to payment.

The memory describes an apparatus for configuring a measuring device to measure the impedance of a subject, the apparatus including a processing system for:

a) receive configuration data, the configuration data being indicative of at least one feature;

b) determine, using the configuration data, instructions that represent the at least one characteristic;

Y,

c) make, at least in part through the instructions, at least one of:

i) impedance measurements to be performed; Y,

ii) analysis of impedance measurements.

The memory describes a method for configuring a measuring device to measure the impedance of a subject, including the method, in a computer system:

a) determine the configuration data necessary for a measuring device, the configuration data being indicative of at least one characteristic; Y,

b) cause the configuration data to be received by a processing system in the measuring device, the processing system being sensitive to the configuration data to configure the measuring device to allow the at least one feature to be used.

Typically, the method includes, in the computer system: determining a device identifier, the device identifier being associated with the measuring device to be configured; and, using the device identifier for at least one of:

i) transfer the configuration data to the measuring device; Y,

ii) encrypt the configuration data.

Typically, the method includes, in the computer system, determining the required configuration data in response to at least one of: payment made by a user of the measuring device; and, the approval of the function.

5

10

fifteen

twenty

25

30

35

40

Four. Five

fifty

55

60

65

Typically, the method includes, in the computer system:

a) determine the regulatory approval of the at least one feature in at least one region;

b) determine at least one measuring device in the at least one region; Y,

c) configure the at least one measuring device.

The memory describes an apparatus for configuring a measuring device to measure the impedance of a subject, including the method, in a computer system:

a) determine the necessary configuration data for a measuring device, the configuration data being indicative of at least one characteristic; Y,

b) make the configuration data received by a processing system in the measuring device, the processing system being sensitive to the configuration data to configure the measuring device to allow the use of at least one function.

The report describes a method for measuring impedance measurements on a subject, in which the method includes, in a processing system:

a) have a first signal applied to the subject;

b) determine at least one parameter relative to at least a second measurement signal across the subject;

c) compare the at least one parameter with at least one threshold; Y,

d) based on the results of the comparison, selectively repeat steps (a) to (d) using a first signal that has a greater magnitude.

Typically, the method includes, in the processing system: determining a type of animal of the subject; and, the selection of the threshold according to the type of animal.

Normally, the threshold is indicative of at least one of: a minimum second signal magnitude; and, a minimum signal to noise ratio for the second signal.

Typically, the method includes, in the processing system: determining at least one parameter relative to the at least one first signal; compare the at least one parameter with the at least one threshold; and, termination impedance measurements selectively based on the results of the comparison.

Normally, the threshold is indicative of a first maximum magnitude of the signal.

The memory describes an apparatus for performing impedance measurements on a subject, in which the apparatus includes a processing system for:

a) have a first signal applied to the subject;

b) determine at least one parameter relative to at least a second signal measured across the subject;

c) compare the at least one parameter with the at least one threshold; Y,

d) based on the results of the comparison, selectively repeat steps (a) to (d) using a first signal that has a greater magnitude.

Typically, the apparatus also includes a power supply of varying magnitude.

The report describes a method of providing an electrode for use in impedance measurement procedures, including the method:

a) provide on a substrate:

i) a series of electrically conductive contact pads; Y,

ii) a corresponding number of conductive tracks of electricity, each track extending from one edge of the substrate to a respective contact pad;

b) apply an insulating layer to the substrate, the insulation layer including a number of openings, and being positioned to thereby cover the tracks with at least a portion of each pad contact aligned with a respective opening; Y,

c) provide a conductive means of electricity in the openings.

Typically the electrically conductive medium is formed from a conductive gel. Typically, the conductive gel is the silver gel / silver chloride.

Typically, the method includes providing a coating layer on the insulating layer to thereby cover the electrically conductive medium.

5

10

fifteen

twenty

25

30

35

40

Four. Five

fifty

55

60

65

Typically, the insulating layer has an adhesive surface that is releasably coupled to the cover layer.

Normally, the substrate is an elongated substrate, and in which the method includes the alignment of the pad contacts along the length of the substrate.

Typically, the method includes providing the tracks and contact tracks using at least one of: screen printing; injection print; and, the deposition of steam. Typically the tracks and contact terminals are formed from silver.

Typically, the method includes forming the substrate by:

a) superimpose a plastic polymer with a shielding material; Y,

b) cover the shielding material with an insulating material.

The memory describes an electrode for use in impedance measurement procedures, the electrode including:

a) a substrate on which it has been provided:

i) a series of electrically conductive contact plates; Y,

ii) a corresponding number of conductive tracks of electricity, each track extending from one edge of the substrate to a respective contact pad;

b) an insulating layer provided on the substrate, the insulation layer including a number of openings, and being positioned to thereby overlap the tracks with at least a portion of each pad contact aligned with a respective opening; Y,

c) a conductive means of electricity provided in the openings.

The report describes a method for use in the diagnosis of conditions in a subject, including the method, in a processing system:

a) determining an encoded value associated with at least one electrode conductor; Y,

b) have at least one measurement of the impedance be made using the coded value.

The report describes a method for use in the diagnosis of conditions in a subject, including the method, in a processing system:

a) determining of an electrode identifier associated with at least one electrode provided in the subject;

b) determine, using the electrode identifier, a position electrode indicative of the position of the at least one electrode on the subject; Y,

c) have at least one impedance measurement made using the electrode position.

The report describes a method for use in the diagnosis of conditions in a subject, including the method, in a processing system:

a) receive configuration data, the configuration data that is indicative of at least one feature;

b) determine, using the configuration data, instructions that represent the at least one characteristic; Y,

c) make the measuring device to carry out, using the instructions, at least one of:

i) impedance measurements; Y,

ii) analysis of impedance measurements.

The report describes a method for use in the diagnosis of conditions in a subject, including the method, in a processing system:

a) determine the necessary configuration data for a measuring device, the configuration data being indicative of at least one characteristic; Y,

b) make the configuration data received by a processing system in the measuring device, the processing system being sensitive to the configuration data to configure the measuring device to allow at least one feature to be used.

The report describes a method for use in the diagnosis of conditions in a subject, including the method, in a processing system:

a) have a first signal applied to the subject;

b) determine at least one parameter relative to at least a second measurement signal across the subject;

5

10

fifteen

twenty

25

30

35

40

Four. Five

fifty

55

60

65

c) compare the at least one parameter with the at least one threshold; Y,

d) based on the results of the comparison, selectively repeat steps (a) to (d) using a first signal that has a greater magnitude.

It will be appreciated that the apparatus and methods described can be used individually or in combination, and can be used for the diagnosis of the presence, absence or degree of a number of conditions and diseases, including, but not limited to edema, pulmonary edema, lymphedema. , body composition, heart function, and the like.

Brief description of the drawings

An example of the present invention will now be described with reference to the accompanying drawings, in which:

Figure 1 is a diagram of an example impedance determination apparatus;

Figure 2 is a flow chart of an example of a process for performing impedance determination;

Figure 3 is a diagram of a second example of an impedance determination apparatus;

Figure 4 is a schematic of an example of a current source circuit;

Figure 5 is a schematic of an example of an intermediate memory circuit for use in voltage detection;

Figures 6A and 6B are a flow chart of a second example of a process for determining impedance;

Figures 7A and 7B are schematic diagrams of an example of an electrode connection;

Figure 8 is a diagram of a third example of an impedance determining apparatus;

Figure 9 is a diagram of a fourth example of an impedance determining apparatus; Y,

Figure 10 is a diagram of a fifth example of an impedance determining apparatus;

Figures 11A and 11B are schematic diagrams of a second example of an electrode connection;

Figures 11C to 11G are schematic diagrams of a third example of an electrode connection;

Figures 12A to 12F are schematic diagrams of an example of the construction of a band electrode;

Figures 12G and 12H are schematic diagrams of an example of a connector arrangement for the band electrode;

Figure 12I is a schematic diagram of the use of a band electrode;

Figure 13 is a schematic of a second example of a current source circuit;

Figure 14 is a flow chart of an example of the use of the current source circuit of Figure 13;

Figure 15 is a flow chart of an overview of an example of the process of updating a measuring device;

Figure 16 is a schematic diagram of an example of a system architecture for updating a measuring device;

Figure 17 is a flow chart of a first example of the process of updating a measuring device;

Figure 18 is a flow chart of a second example of the process of updating a measuring device; Y,

Figure 19 is a diagram of an example of a housing configuration for an impedance determination apparatus.

Detailed description of preferred embodiments

An example of a suitable apparatus for performing an analysis of the bioelectrical impedance of a subject will now be described with reference to Figure 1.

As shown, the apparatus includes a measuring device 1 that includes a processing system 2 coupled to a signal generator 11 and a sensor 12. In use, the signal generator 11 and the sensor 12 are coupled to the respective electrodes 13 , 14, 15, 16, provided on a subject S, through cables L, as shown. An optional external interface 23 can be used to couple the measuring device 1 to one or more peripheral devices 4, such as an external database or computer system, a barcode scanner, or the like.

In use, the processing system 2 is adapted to generate control signals, which cause the signal generator 11 to generate one or more alternating signals, such as voltage or current signals, which can be applied to a subject S, a through the electrodes 13, 14. The sensor 12 then determines the voltage across or through the subject S, using the electrodes 15, 16 and transfers the appropriate signals to the processing system 2.

Accordingly, it will be appreciated that the processing system 2 can be any form of processing system, which is suitable for the generation of appropriate control signals and the interpretation of an indication of the measured signals to thereby determine the bioelectrical impedance of the subject, and,

5

10

fifteen

twenty

25

30

35

40

Four. Five

fifty

55

60

65

optionally, determine other information, such as parameters, absence, presence or degree of edema, or the like.

The processing system 2 can therefore be an appropriately programmed computer system, such as a laptop, desktop, PDA, smartphone or the like. Alternatively, the processing system 2 can be formed from specialized hardware. Similarly, the I / O device can be of any suitable form such as a touch screen, a keyboard and the screen, or the like.

It will be appreciated that the processing system 2, the signal generator 11 and the sensor 12 can be integrated in a common housing and therefore form an integrated device. Alternatively, the processing system 2 can be connected to the signal generator 11 and the sensor 12 through wired or wireless connections. This allows the processing system 2 to be provided remotely to the signal generator 11 and the sensor 12. Therefore, the signal generator 11 and the sensor 12 can be provided in a nearby unit, or used by the subject S, while the processing system 2 is located remotely with the subject S.

In one example, the external pair of electrodes 13, 14 are placed in the thoracic region and the neck of the subject S. However, this depends on the nature of the analysis that is performed. Thus, for example, while this arrangement of electrodes is suitable for the analysis of cardiac function, in lymphedema, the electrodes are normally positioned at the extremities, as required.

Once the electrodes are placed, an alternating signal is applied to the subject S. This can be done either by applying an alternating signal at a plurality of frequencies simultaneously, or by applying a series of alternating signals at different frequencies. sequentially The frequency range of the applied signals may also depend on the analysis performed.

In one example, the signal applied is a frequency current rich from a fixed current source, or otherwise limited, so that it does not exceed the auxiliary current of the maximum allowed subject. However, as an alternative, the voltage signals can be applied, with an induced current in the subject being measured. The signal can be either a constant current, the impulse function or a constant voltage signal where the current is measured so that it does not exceed the auxiliary current of the maximum allowed subject.

A difference and / or the potential current is measured between an internal pair of electrodes 15, 16. The acquired signal and the measured signal will be an overlap of the potentials generated by the human body, such as the ECG and the potentials generated by the current applied

Optionally, the distance between the internal pair of electrodes can be measured and recorded. Similarly, other parameters related to the subject can be recorded, such as height, weight, age, sex, health status, interventions and the date and time they occurred. Other information, such as current medication, can also be registered.

To aid in the precise measurement of impedance, the damping circuits can be placed in the connectors that are used to connect the voltage sensing electrodes 15, 16 to the cables L. This ensures the precise detection of the voltage response of the subject S, and, in particular, helps eliminate contributions to the measured voltage due to the response of the cables L, and reduce signal loss.

This in turn greatly reduces the artifacts caused by the movement of the L cables, which is especially important during dialysis since the sessions usually last several hours and the subject moves around and changes position during this time.

An additional option is to differentially measure the voltage, which means that the sensor used to measure the potential on each electrode 15, 16 only has to measure half the potential compared to a single composition system.

The current measurement system can also have buffers placed in the connectors between electrodes 13, 14 and the L wires. In one example, the current can also be conducted or transmitted through the subject S symmetrically, which in turn reduces to a large extent the parasitic capacities in half the current in common mode. Another particular advantage of using a symmetric system is that the microelectronics incorporated in the connectors for each electrode 13, 14 also eliminates parasitic capacities that arise when the subject S, and therefore the cables L move.

The acquired signal is demodulated to obtain the impedance of the system at the applied frequencies. A suitable method for demodulation of overlapping frequencies is to use a Fast Fourier Transform (fFt) algorithm to transform the time domain data to the frequency domain. This is typically used when the applied current signal is a superposition of applied frequencies. Another technique that does not require measured signal windows is a sliding window FFT.

5

10

fifteen

twenty

25

30

35

40

Four. Five

fifty

55

60

65

In the case that the applied current signals are formed from a sweep of different frequencies, then it is more typical to use a treatment technique such as multiplying the measured signal with a reference sine wave and cosine derived from the signal generator, or with measured sine and cosine waves, and the integration of more than a whole number of cycles. This process rejects any harmonic response and significantly reduces random noise.

Other suitable digital and analog demodulation techniques will be known by experts in the field.

The impedance or admittance measurements are determined from the signals at each frequency by comparing the engraving voltage and current signal. The demodulation algorithm will produce an amplitude and a phase signal at each frequency.

An example of the operation of the apparatus for performing the impedance analysis will now be described with reference to Figure 2.

In step 100, the processing system 2 operates to generate control signals that are provided to the signal generator 11 in step 110, thereby causing the signal generator to apply an alternating current signal to the subject S, in the stage 120. Typically, the signal is applied to each of a series of fi frequencies to allow the analysis of multiple frequencies to be performed.

In step 130 the sensor 12 detects the voltage signals through the subject S. In step 140 the measuring device operates to digitalize and sample the voltage and current signals through the subject S, which allows these to be used to determine instantaneous impedance values for subject S in step 150.

A specific example of the apparatus will now be described in more detail with respect to Figure 3.

In this example, the processing system 2 includes a first processing system 10 having a processor 20, a memory 21, an input / output (I / O) of the device 22, and an external interface 23, coupled between sf through of a bus 24. The processing system 2 also includes a second processing system 17, in the form of a processing module. A controller 19, such as a Micrologic controller, can also be provided to control the activation of the first and second processing systems 10, 17.

In use, the first processing system 10 controls the operation of the second processing system 17 to allow different impedance measurement procedures to be implemented, while the second processing system 17 performs specific processing tasks, thereby reducing the requirements of processing in the first processing system 10.

Therefore, the generation of the control signals, as well as the process for determining instantaneous impedance values are carried out by the second processing system 17, which can therefore be formed from custom hardware, or similar. In a particular example, the second processing system 17 is formed from a programmable field gate matrix (FPGA), although any suitable processing module, such as a magnetologic module, can be used.

The operation of the first and second processing systems 10, 17, and the controller 19 is typically controlled using one or more appropriate instruction sets. These may be in any suitable form, and therefore may include, software, firmware, integrated systems, or the like.

The controller 19 typically functions to detect the activation of the measuring device by using an on / off switch (not shown). Once the controller detects the activation of the device, the controller 19 executes predefined instructions, which in turn causes the activation of the first and second processing systems 10, 17, including the control of the energy supply to the processing systems according to be necessary.

The first processing system 10 can then operate to control the instructions, such as the firmware, implemented by the second processing system 17, which in turn alters the operation of the second processing system 17. In addition, the first processing system 10 it can work to analyze the impedance determined by the second processing system 17, to allow the biological parameters to be determined. Accordingly, the first processing system 10 may be formed of custom hardware or the like, running appropriate software applications to enable the processes described in more detail to be implemented below.

In this example, the second processing system 17 includes a PCI bridge 31 coupled to the programmable module 36 and a bus 35, as shown. The bus 35 is in turn coupled to the processing modules

5

10

fifteen

twenty

25

30

35

40

Four. Five

fifty

55

60

65

32, 33, 34, which interaction with the ADCs (analog-digital converters) 37, 38, and a DAC (digital-analog converter) 39, respectively.

The programmable module 36 is formed from programmable hardware, whose operation is controlled by the instructions, which are normally downloaded from the first processing system 10. The firmware specifying the hardware configuration 36 may reside in flash memory (not shown) , in memory 21, or it can be downloaded from an external source through external interface 23.

Alternatively, the instructions can be stored within the memory incorporated in the second processing system 17. In this example, the first processing system 10 usually selects the firmware for the application, before it is implemented by the second processing system. 17. This can be achieved to allow selective activation of functions encoded in the firmware, and can be done, for example, using configuration data, such as a configuration file, or instructions representing software or firmware applications, or the like , as will be described in more detail below.

In any case, this allows the first processing system 10 to be used to control the operation of the second processing system 17, to allow predetermined current sequences to be applied to the subject S. Thus, for example, different firmware is used if The current signal is to be used to analyze the impedance at a number of frequencies simultaneously, for example, by the use of a current signal formed from a number of superimposed frequencies, as compared to the use of applied current signals at different frequencies sequentially.

An example of a specific form of signal generator 11 in the form of a current source circuit is shown in Figure 4.

As shown, the current source includes three differential amplifiers of fixed or variable gain A1, A2, A3 and three operational amplifiers A4, A5, A6, a number of resistors R1, ... R17 and capacitors C1, ... C4 , interconnected as shown. The current source also includes cables 41, 42 (corresponding to the cables L in Figure 1) that connect the current source to the electrodes 13, 14 and a switch SW to short the cables 41,42, as will be described in more detail below.

Connections 45, 46 can also be provided to allow the current applied to subject S. to be determined. Normally, this is achieved by connection 46. However, connection 45 can also be used as shown in dotted lines to allow signal losses within the conductors and other circuits that must be taken into account.

In general, the cables used are coaxial cables with an unbraided shield and a multi-strand core with a polystyrene dielectric. This provides good conductive and noise properties, in addition to being sufficiently flexible to avoid problems with the connections from measuring device 1 to subject S. In this case, resistors R12, R13 decouple the outputs of amplifiers A5, A6 from the capacitances associated with cable.

In use, the current source circuit receives current control signals I +, I- from DAC 39, with these signals being filtered and amplified, to thereby form the current signals that can be applied to the subject S a through electrodes 13, 14.

In use, when amplifiers A1, .... A6 are initially activated, this can lead to a lower, and within the limits of safety, increased transient current. As the current is applied to the subject, this may result in the generation of a residual field through the subject S. To avoid this field when reading, the SW switch is generally activated before the measurements taken into account , to cut the current circuit and, therefore, discharge any residual field.

Once the measurement is started, an indication of the current applied to the subject can be obtained through any of one of the connections 45, 46, which are connected to the ADC 38, as shown by the dotted lines.

This allows the current supplied through the subject to be determined accurately. In particular, by using the actual applied current, in comparison to the estimation of the applied current based on the control signals I +, I-, this takes into account the non-ideal behavior of the components in the current source , and can also take into account the effects of the cables 41, 42, of the applied current.

In one example, amplifier A3 and associated components can be provided in a housing coupled to electrodes 12, 13, which allows a more precise detection of the current applied to the subject. In particular, this prevents the measurement of the effects of the cable, such as the loss of signal on the L cables.

The above is an example of a source of non-symmetric current and it will be appreciated that sources of symmetrical currents can be used alternatively.

5

10

fifteen

twenty

25

30

35

40

Four. Five

fifty

55

60

65

An example of the buffer used for the voltage electrodes is shown in Figure 5. In this example, each electrode 15, 16 is coupled to a buffer circuit 50A, 50B.

In this example, each buffer 50A, 50B includes amplifiers A10, A11 and a number of resistors R21, ..., R26, interconnected as shown. In use, each buffer 50A, 50B is connected to a respective electrode 15, 16 through connections 51, 52. Buffers 50A, 50B are also connected via wires 53, 54 to a differential amplifier 55, which acts as the signal sensor 12, which in turn is coupled to the ADC 37. Therefore, it will be appreciated that a respective buffer circuit 50A, 50B is connected to each of the electrodes 15, 16, and then to a differential amplifier , which allows you to determine the potential difference across the subject.

In one example, cables 53, 54 correspond to cables L shown in Figure 1, allowing intermediate memory circuits 50A, 50B to be provided in the connector housing coupled to electrodes 15, 16, as will be described in more detail below.

In use, the amplifier A10 amplifies the detected signals and drives the core of the cable 53, while the amplifier A11 amplifies the detected signal and the shield units of the cables 51, 53. Resistors R26 and R25 decouple the outputs of the amplifier of the capacitances associated with the cables, although the need for this depends on the amplifier selected.

Again, this allows multi-core shielded cables to be used to establish the connections to the voltage electrodes 15, 16.

An example of operation of the apparatus will now be described with reference to Figures 6A to 6C.

In step 200 an operator selects a type of impedance measurement, following the first processing system 10. This can be achieved in a number of ways and it is typically implied to have the first processing system 10 storing a number of different profiles, each one of which corresponds to a corresponding impedance measurement protocol.

Thus, for example, when determining cardiac function, it will be typical to use a different applied current sequence and a different impedance analysis, as compared to measurements that measure lymphedema, body composition, pulmonary edema, or the like. The profile is normally stored in memory 21, or alternatively it can be downloaded from flash memory (not shown), or through external interface 23.

Once an appropriate type of measurement has been selected by the operator, this will cause the first processing system 10 to load the firmware of the desired code module into the programmable module 36 of the second processing system 17 in step 210, or will that the built-in firmware be activated. The type of code module used will depend on the preferred implementation and, in one example, this is formed from a wishbone code module, although this is not essential.

In step 220, the second processing system 17 is used to generate a sequence of digital control signals, which are transferred to the DAC 39 in step 230. This is typically accomplished using the processing module 34, causing the module to generate a predetermined sequence of signals based on the selected impedance measurement profile. Therefore, this can be achieved by having the second processing system 17 program the processing module 34 to cause the module to generate the necessary signals.

The DAC 39 converts the digital control signals into analog control signals I +, I- which are then applied to the current source 11 in step 240.

As described above, the current source circuit shown in Figure 4 operates to amplify and filter the electrical control signals I +, I- in step 250, applying the resulting current signals to the electrodes 13, 14 in Stage 260

During this process, and as mentioned above, the current circuit through the subject may optionally be shorted in step 270, with the SW switch, to thereby discharge any residual field in the subject S, before performing the readings

In step 280, the measurement procedure begins, detecting the tension in the subject from the electrodes 15, 16. In this regard, the voltage across the electrodes is filtered and amplified by the buffer circuit shown in Figure 5, in step 290, with the resulting analog voltage signals V that are supplied to ADC 37 and digitized in step 300. Simultaneously, in step 310, the current applied to subject S is detected through a of connections 45, 46, with analog current signals I being digitized using ADC 38 in step 320.

5

10

fifteen

twenty

25

30

35

40

Four. Five

fifty

55

60

65

The digitized voltage and current signals V, I are received by the processing modules 32, 33 in step 330, these being used for preliminary signal processing performed in step 340.

The processing performed will depend once again on the impedance measurement profile, and on the consequent configuration of the processing modules 32, 33. This may include, for example, the processing of the voltage signals V to extract the ECG signals. The signals are also usually filtered to ensure that only signals at the applied frequencies f are used in the determination of impedance. This helps reduce the effects of noise, as well as reducing the amount of processing required.

In step 350, the second processing system 17 uses the processing signals to determine the voltage and current signals at each applied fi frequency, these being used in step 360 to determine the instantaneous impedance values at each applied fi frequency.

The ADCs 37, 38 and the processing modules 32, 33 are normally adapted for sampling and processing the voltage and current signals V, I in parallel, so that the voltage induced in the corresponding applied current is analyzed simultaneously . This reduces the processing requirements, avoiding the need to determine which voltage signals are measured at the applied frequency. This is achieved by having the processing modules 32, 33 show the digitized signals received from the ADCs 37, 38, using a common clock signal generated by the processing module 36, thereby ensuring synchronization of the sampling Of the signal.

Once the instantaneous impedance values have been derived, they can be subjected to further processing, either in the first processing system 10, or the second processing system 17, in step 370. The processing of the instantaneous impedance signals It will be carried out in a number of different ways depending on the type of analysis to be used, and this in turn will depend on the selection made by the operator in step 200.

Accordingly, it will be appreciated by those skilled in the art that a variety of different current sequences can be applied to the subject by making a selection of the appropriate type of measurement. Once this has been done, the FPGA works to generate a sequence of appropriate control signals I +, I-, which are applied to the subject S using the power supply circuit shown in Figure 4. The induced voltage to The subject is then detected using the buffer circuit shown in Figure 5, allowing impedance values to be determined and analyzed by the second processing system 17.

The use of the second processing system 17 allows the processing majority to be performed using custom configured hardware. This has a number of benefits.

First, the use of a second processing system 17 allows the custom hardware configuration to be adapted through the use of appropriate firmware. This in turn allows a single measuring device to be used to perform a variety of different types of analysis.

Second, this greatly reduces the processing requirements in the first processing system 10. This in turn allows the first processing system 10 to be implemented using relatively simple hardware, while still allowing the measuring device to perform a Sufficient analysis to provide interpretation of impedance. This may include, for example, the generation of a "Wessel" frame, using the impedance values to determine the parameters related to cardiac function, as well as determining the presence or absence of lymphedema.

Thirdly, this allows the measuring device 1 to be updated. Thus, for example, if an improvement of the analysis algorithms is created, or an improved current sequence determined for a specific type of impedance measurement, the measuring device can be updated by downloading new firmware through the flash memory (not shown) or external interface 23.

It will be appreciated that, in the previous examples, the processing is performed partially by the second processing system 17, and partially by the first processing system 10. However, it is also possible to perform the processing by a single element, such as an FPGA , or a more generalized processing system.

As the FPGA is a custom processing system, it tends to be more efficient in the operation of a more generic processing system. As a result, if an FPGA is used only, it is generally possible to use a reduced total amount of processing, which allows a reduction in energy consumption and dimensions. However, the degree of flexibility and, in particular, the processing interval and the analysis of the impedance that can be performed is limited.

5

10

fifteen

twenty

25

30

35

40

Four. Five

fifty

55

60

65

On the contrary, if only one generic processing system is used, flexibility is improved at the cost of a decrease in efficiency and with the consequent increase in size and consumption in January.

Consequently, the above described example seeks a balance, providing a personalized treatment in the form of an FPGA to perform partial processing. This may, for example, allow impedance values to be determined. Subsequent analysis, which generally requires a greater degree of flexibility below, can be implemented with the generic processing system.

An additional disadvantage of using an FPGA only is that it complicates the process of updating processing, for example, if improved processing algorithms are implemented.

Electrode connections

An example of an electrode connection apparatus is shown in Figures 7A and 7B.

In particular, in this example, the connector includes circuits provided on a substrate, such as a PCB (printed circuit board) 6l, which in turn is mounted in a housing 60, as shown. The housing 60 includes an arm 62 which is pushed towards a contact 63 provided on the substrate 61. The substrate 61 is then coupled to a respective one of the ADCs 37, 38 or dAc 39, through suitable cables are generally shown in L, such as cables 41,42, 53, 54.

In use, the connector is coupled to a conductive electrode substrate 65, such as a silver-coated plastic, and which in turn has a conductive gel 64, such as silver gel / silver chloride therein. The arm 62 presses the conductive electrode substrate 65 against the contact 63, thereby electrically coupling the conductive gel 64 to the circuit provided on the substrate 61.

This ensures a good electrical contact between the measuring device 1 and the subject S, as well as reduces the need for cables between the electrodes 13, 14 and the input of the voltage buffers, eliminating the need for additional cables, which represents an expense, as well as a source of noise inside the device.

In this example, the edges and corners of the housing 60, the arm 62 and the substrate 65 are curved. This is to reduce the possibility of a subject being injured when the connector is attached to the electrode.

This is of particular importance when electrodes are used in lymphedema trauma, when even a small area of skin contact can cause serious complications.

To further improve the usability of the housing, the housing may be formed of a material that has a low coefficient of friction and / or is spongy or elastic. Again, these properties help reduce the likelihood of the subject being injured when the housing is coupled to the electrode.

Electrical isolation

A further development of the apparatus will now be described with reference to Figure 8.

In this example, the second processing system 17 is formed from two respective FPGA portions 17A, 17B. The two FPGA portions 17A, 17B are interconnected through an electrically insulated connection shown generally by the line of points 17C. The electrically isolated connection could be achieved, for example, using an inductive loop connection, wireless links or the like.

This division in the FPGA can be used to ensure that the measuring device 1 is electrically isolated from the subject S. This is important, for example, when taking readings with a high degree of accuracy.

In this example, the second processing system 17 will typically be carried out in such a way that the operation of the second portion of FPGA 17B is substantially identical for all types of measurement. As a result, there is no requirement to load firmware in the second portion of FPGA 17B to allow different types of impedance analysis.

In contrast to this, the first portion of FPGA 17A typically applies firmware depending on the type of impedance measurement in a manner substantially as described above.

Therefore, it will be appreciated that this provides a mechanism by which the measuring device 1 is electrically isolated from the subject, while still allowing to achieve the advantages of using the second processing system 17.

Alternatively, equivalent electrical isolation can be obtained by providing a single electrically isolated FPGA from the first processing system 10.

5

10

fifteen

twenty

25

30

35

40

Four. Five

fifty

55

60

65

In this example, the second portion of FPGA 17B can be provided in a subject unit, which is generally shown in 2, which includes cable connections.

This allows an individual measuring device 1 to communicate with a number of different subject units, each of which is associated with a respective subject S. This allows the measuring device 1 to provide centralized control of a series of different subjects through a way of a number of 2 subject units. This in turn allows analyzing a series of subjects that have been analyzed in sequence without having to reconnect each subject S each time an analysis is to be performed.

Wire calibration

To aid in the interpretation of impedance measurements, it is useful to take into account the electrical properties of the connection cables and associated circuits.

To achieve this, the corresponding cables and connections can be encoded with the calibration information. This may include, for example, using specific values for the respective resistors in the current source, or buffer circuits shown in Figures 4 and 5. Thus, for example, the value of resistors R12, R13, R26 can be selected based on the properties of the corresponding cables.

In this case, when the conductors are connected to the measuring device 1, through the corresponding ADCs 37, 38, the processing modules 32, 33 can interrogate the circuits with appropriate voting signals to thereby determine the value of the corresponding resistance. Once this value has been determined, the second processing system 17 can use this to modify the algorithm used to process the voltage and current signals to ensure that the correct impedance values are thereby determined.

In addition to this, the resistance value can also act as a cable identifier, to allow the measuring device to identify the cables and ensure that only authorized authentic cables are used. Thus, for example, if the determined resistance value does not correspond to a predetermined value, this can be used to indicate that non-original cables are being used. In this case, since the quality of the cable can have an effect on the accuracy of the analysis of the resulting impedance, it may be desirable to generate an error or warning message indicating that incorrect cables are in use. Alternatively, the second processing system 17 can be adapted to stop the processing of the measured current and voltage signals. This allows the system to guarantee that only genuine cables are used.

This can also be improved by using a unique identifier associated with each cable connection circuit. In this case, a unique identifier can be encoded within an IC provided as part of the circuits of the current source or voltage buffer. In this case, the measuring device 1 interrogates the unique identifier and is compared with unique identifiers stored in the local memory, or in a central database, which allows genuine cables to be identified.

This process can also be used to control the number of times a cable has been used. In this case, each time a cable is used, data that reflects the use of the cable is recorded. This allows the cables to have a useful life using previously designated quotas, and once the number of times the cable is used reaches the quota, further measurements using the conductors can be avoided. Similarly, a temporary limitation can be applied by providing an expiration date associated with the cable. This may be based on the date the cable was created or was first used depending on the preferred implementation.

It will be appreciated that when the use of the cable is recorded, problems may arise if this is recorded locally. In particular, this could allow an advantage of being reused with a different measuring device. To avoid this, the cables can be configured with an ID that is set by the measuring device on first use. This can be used to limit the use of cables in an individual measuring device.

This can be used to ensure that the cables are replaced correctly in accordance with a predetermined useful life, thus helping to ensure the accuracy of the measured impedance values.

Multiple channel

An additional variation to the apparatus is shown in Figure 9.

In this example, the apparatus is adapted to provide multiple channel functionality that allows different segments of the body to undergo impedance analysis substantially simultaneously. In this example, this is achieved by providing a first and second treatment modules 32A, 32B, 33A, 33B, 34A, 34B, a first and second ADCs and DACs 37A, 37B, 38A, 38B, 39A, 39B, as well as a first and second voltage and current circuits 11A, 11B, 12A, 12B, in parallel, as shown.

5

10

fifteen

twenty

25

30

35

40

Four. Five

fifty

55

60

65

Therefore, the measuring device 1 includes two separate impedance measurement channels indicated by the use of reference numbers A, B. In this case, this allows the electrodes to be attached to the body segments, such as different extremities, with measurements taken from each segment in a substantially simultaneous manner.

As an alternative to the arrangement described above, multiple channels may alternatively be implemented by using two separate second processing modules 17, each being associated with a respective channel. Alternatively, the signals applied to each channel can be applied through multiplexers positioned between ADCs 37, 38 and DAC 39 and electrodes.

It will be appreciated that, although two channels are shown in the previous example, this is for reasons of clarity only, and any number of channels can be provided.

Switching Provision

Figure 10 shows an example of an impedance measurement apparatus that includes a switching arrangement. In this example, the measuring device 1 includes a switching device 18, such as a multiplexer, for connecting the signal generator 11 and the sensor 12 to the cables L. This allows the measuring device 1 to control which cables L are connected to signal generator 11 and sensor 12.

In this example, a unique set of cables and connections is shown. This provision can be used in a number of ways. For example, by identifying the electrodes 13, 14, 15, 16 to which the measuring device 1 is connected, this can be used to control to which of the cables L the signals are applied, and through which cables They can measure the signals. This can be achieved by having the user provide an appropriate indication through the input device 22, or by having the measuring device 1 automatically detect electrode identifiers, as will be described in more detail below.

Alternatively, however, the arrangement can be used with multiple cables and electrodes to provide the functionality of multiple channels as described above.

Electrode configuration

An example of an alternative electrode configuration will now be described with reference to Figures 11A and 11B.

In this example, the electrode connector is formed from a housing 1100 having two arms 1101, 1102 arranged to engage with an electrode substrate 1105, to thereby couple the housing 1100 to the substrate 1105. A contact 1103 mounted on a lower side of the arm 1102, is pressed into contact and / or engagement with an electrode contact 1104 mounted on a surface of the electrode substrate 1105. The electrode also includes a conductive gel 1106, such as a silver gel / silver chloride , electrically connected to contact 1104. This can be achieved, either by the use of a conductive track, such as a silver track, or by the use of a conductive substrate, such as silver-coated plastic.

This allows the cable L to be electrically connected to the conductive gel 1106, allowing the current to be applied to and / or a measured voltage of the subject S to which they are attached. It will be appreciated that, in this example, the housing 1100 described above may also contain the buffer memory circuit 50, or all or part of the current source circuit shown in Figure 4, in a manner similar to that described above. with respect to figure 7.

Alternatively, more complex interconnections can be provided to allow the measuring device 1 to identify specific electrodes, or types of electrodes.

This can be used by the measuring device 1 to control the measuring procedure. For example, the detection of one type of electrode by the analysis system 2 can be used to control the measurements and the calculation of different impedance parameters, for example, to determine indicators for use in the detection of edema, monitoring of the cardiac function, or the like.

Similarly, the electrodes may be provided with visual marks indicative of the position in the subject to which the electrode should be attached. For example, an image of a left hand can be shown if the electrode pad is to be attached to the left hand of a subject. In this case, the identification of the electrodes can be used to allow the measuring device 1 to determine where the electrode is attached in the subject and, therefore, to control the application and measurement of signals accordingly.

An example of this will now be described with reference to Figures 11C to 11G. In this example, contact 1103 is formed from a contact substrate 1120, such as a PCB, having a number of connector elements 1121, 1122, 1123, 1124, formed from conductive contact plates, usually silver or similar. The connecting elements are connected to the cable L through respective electrically conductive tracks 1126,

5

10

fifteen

twenty

25

30

35

40

Four. Five

fifty

55

60

65

Typically formed from silver, and provided on the contact substrate 1120. The cable L includes a series of individual cables, each electrically coupled to a respective one of the connecting elements 1121, 1122, 1123, 1124.

In this example, the electrode contact 1104 on the electrode substrate 1105 typically includes an electrode contact substrate 1130, which includes electrode connector elements 1131, 1132, 1133, 1134, typically formed from silver contact pads or Similar. The electrode connector elements 1131, 1134 ... are positioned so that, in use, when the electrode connector 1100 is connected to an electrode, the connector elements 1121 ... 1124 contact the electrode connection elements 1131 , ... 1134 to allow transfer of electrical signals with measuring device 1.

In the examples of Figures 11D to 11G, the connecting element 1131 is connected to the conductive gel 1106, through an electrically conductive track 1136, typically a silver track that extends into the lower part of the electrode substrate 1105. This can be used by the measuring device 1 to apply a current, or measure a voltage across the subject S.

In addition, the selective of the connecting elements 1132, 1133, 1134 are also interconnected in four different arrangements of respective connectors 1136a, 1136B, 1136C, 1136D. This allows the measuring device 1 to detect which of the electrode contacts 1122, 1123, 1124 are interconnected; thanks to the connectors, 1136a, 1136B, 1136C, 1136D, with four different combinations that allow the identification of the four different electrodes.

Accordingly, the arrangement of Figures 11D to 11G can be used to provide four different electrodes, used as, for example, two current supply 13, 14 and two voltage measuring electrodes 15, 16.

In use, the measuring device 1 operates having the second processing signals of the system 17 cause to be applied to the corresponding cables within each of the cables L, which allows measuring the conductivity between the connection elements 1122, 1123, 1124. This information is then used by the second processing system 17 to determine which cables L are connected to which of the electrodes 13, 14, 15, 16. This allows the first processing system 10 or the second processing system 17 control the multiplexer 18 in the example of figure 10, to correctly connect the electrodes 13, 14, 15, 16 to the signal generator 11, or to the signal sensor 12.

In this example, the individual applying the electrode pads to the subject can simply place the electrodes 13, 14, 15, 16 on the subject in the position indicated by the visual marks provided therein. The cables can then be connected to each of the electrodes, allowing the measuring device 1 to automatically determine to which electrode 13, 14, 15, 16 each cable L has been connected and then apply the appropriate measured current and voltage signals . This avoids the complexity of securing the correct electrodes that are connected through the correct L wires.

It will be appreciated that the process described above allows the identification of the electrode simply by applying currents to the electrode connector. However, other suitable identification techniques can be used, for example, by the use of optical coding. This could be achieved, for example, by providing a visual marker, or a series of physical markers suitably arranged on electrode connector 1104, or electrode substrate 1105. These could then be detected by an optical sensor mounted on connector 1100, as will appreciate by those skilled in the art.

Alternatively, the identifier for the electrodes can be identified by an encoded value, represented by, for example, the value of a component in the electrode, such as a resistor or a capacitor. Therefore, it will be appreciated that this can be achieved in a manner similar to that described above with respect to cable calibration.

An example of an alternative electrode configuration will now be described with reference to Figures 12A to 12F. In this particular example, the electrode is a 1200 band electrode, which includes a series of separate electrodes. In this example, the electrode is formed from an elongated substrate 1210 such as a plastic polymer coated with material and an insulating shielding overlay material.

A number of electrically conductive tracks 1220 are provided on the substrate, which extends from one end of the substrate 1211 to the respective conductive contact terminals 1230, separated along the length of the substrate in sequence. This allows a connector similar to the connectors described above, but with the corresponding connections, to be electrically coupled to tracks 1220.

The tracks 1220 and the contact pads 1230 may be provided on the substrate 1210 in any one of a number of ways, including, for example, screen printing, inkjet printing, vapor deposition, or the like, and generally formed from silver or other similar material. It will be appreciated, without

5

10

fifteen

twenty

25

30

35

40

Four. Five

fifty

55

60

65

However, contact tracks and terminals should be formed from similar materials to prevent signal drift.

Upon application of the contact pads 1230 and the tracks 1220, an insulating layer 1240 is provided with a number of openings 1250 aligned with the contact pads of the electrode 1230. The insulating layer is typically formed from a plastic polymer coated with material and an insulating superimposed shielding material.

To ensure proper conduction between the contact pads 1230, and the subject S, it is typical to apply a conductive gel 1260 to the contact pads 1230. It will be appreciated that this example gel can be provided in each of the openings 1250 as sample.

A removable cover 1270 is then applied to the electrode, to maintain the sterility of the electrode and / or the moisture level in the gel. This can be in the form of a tear strip or similar that when removed exposes the conductive gel 1260, allowing the electrode to be fixed to the subject S.

In order to guarantee the quality of the signal, which is typical for each of the tracks 1220 to comprise a shield track 1221, and a signal track 1222, as shown. This allows the shield over wires L, such as wires 41, 42, 51 to be connected to shield track 1221, with the core of the cable that is coupled to signal track 1222. This allows shielding with the electrode to be provided. , to help reduce interference between applied and measured signals.

This provides a simple and cheap fast method to produce band electrodes. It will be appreciated that similar screen printing techniques can be used in the electrode arrangements shown in Figures 7A and 7B, and 11A-11G.

The band electrode can be used together with a magnetic connector as will now be described with respect to Figures 12G and 12H. In this example, the band electrode 1200 includes two magnets 1201A, 1201B placed at the end 1211 of the substrate 1210. The connector is formed from a connector substrate 1280 having magnets 1281A, 1281B provided therein. Connection elements 1282 are also provided, and these in turn can be connected to appropriate L cables.

The magnets 1201A, 1281A; 1201B (not shown for clarity), 1281B may be arranged to magnetically align and engage, to press the connector substrate 1280 and the band electrode 1200 together. The correct alignment of the poles of the magnets 1201A, 1281A; 1201B, 1281B can also be used to ensure the correct positioning and orientation of the connector substrate 1280 and the band electrode, which can ensure the correct alignment of the connection elements 1282, with the corresponding tracks 1220, on the band electrode 1200 .

It will be appreciated that this can be used to ensure a correct connection with the electrode, and that a similar magnetic alignment technique can be used in the connectors described above.

In use, the band electrode may be attached to the subject's torso, as shown in Figure 12I. The electrode will typically include an adhesive surface, which allows the subject to stick. However, a belt 1280 can also be used, to help retain the electrode 1200 in its position. This provides an electrode that is easy to place and position on the subject and, however, can be used for a prolonged period, if necessary. The band electrode 1200 may also be placed on the subject in other places, such as on the torso side of the subject, or laterally above the navel, as shown.

The 1200 band electrode provides enough electrodes to allow monitoring of cardiac function. In the previous example, the band electrode includes six electrodes, however, any suitable number can be used, although at least four electrodes are typically required.

Variable current

An additional feature that can be implemented in the previous measuring device is the provision of a signal generator 11 capable of generating a variable force signal, such as a variable current. This can be used to allow the measuring device 1 to be used with different animals, to detect problems with electrical connections, or to overcome noise problems.

To achieve this, the current source circuit shown in Figure 4 is modified as shown in Figure 13. In this example, the resistance R10 in the current source circuit of Figure 4 is replaced with a variable resistance VR10. The alteration of the resistance of the VR10 resistor will result in a corresponding change in the magnitude of the current applied to the subject S.

5

10

fifteen

twenty

25

30

35

40

Four. Five

fifty

55

60

65

To reduce noise and interference between the current source circuit and the control, which is usually achieved using the second processing module 17, it is typical to electrically isolate the variable resistor 17 from the control system. Therefore, in one example, the variable resistance VR10 is formed by a light dependent resistor. In this example, a light emitting diode (LED) or other lighting source can be provided, as shown in L1. The LED L1 can be coupled to a variable power supply P in any suitable way. In use, the power supply P, is controlled by the second processing module 17, thereby controlling the intensity of light generated by the LED L1, which in turn allows the VR10 resistor to vanish and, therefore, the applied current.

To operate the measuring device 1, the first processing system 10 and the second processing system 17 typically apply the process described in Figure 14. In this example, in step 1400 the user selects a measurement or a type of animal that use the input / output device 22.

In step 1410, the first processing system 10 and the second processing system 17 interaction to determine one or more threshold values depending on the type of measurement or animal selected. This can be achieved in any one of a number of ways, such as by having the first processing system 10 retrieve the threshold values from memory 21 and transferring them to the second processing system 17, although any suitable mechanism may be used. In general, multiple thresholds can be used to specify different operating characteristics, for signal parameters such as a maximum current that can be applied to the subject S, the minimum voltage required to determine an impedance measurement, a minimum signal to noise, or the like

In step 1420, the second processing system 17 will activate the signal generator 11, causing a signal to be applied to the subject S. In step 1430, the response signal at the electrodes 15,16 is measured using the sensor 12 with signals indicative of the signal that is returned to the second processing system 17 in step 1430.

In step 1440, the second processing system 17 compares the at least one parameter of the measured signal with a threshold to determine if the measured signal is acceptable in step 1450. This may involve, for example, determining whether the signal at levels of noise within the measured voltage signal is above the minimum threshold or are related to determine if the signal is above a minimum value.

If the signal is acceptable, the impedance measurements can be made in step 1460. If not, in step 1470 the second processing system 17 determines whether the applied signal has reached a maximum allowed. If this has occurred, the process ends in step 1490. However, if the maximum of the signal has not yet been reached, the second processing system 17 will work to increase the magnitude of the current applied to the subject S in step 1480 before returning to step 1430 to determine a new measured signal.

Accordingly, this allows the current or voltage applied to the subject S to be gradually increased until a suitable signal can be measured to allow determined impedance values, or until a maximum current or voltage value for the subject is reached.

It will be appreciated that the selected thresholds, and the initial current applied to the subject S in step 1420 is normally selected depending on the nature of the subject. Thus, for example, if the subject is a human being, it is typical to use a current of magnitude lower than if the subject is an animal, such as a mouse or the like.

Device Updates

An example of a process for updating the measuring device will now be described with reference to Figure 15.

In one example, in step 1500, the process involves determining a measuring device 1 to be configured with an update, or the like, before creating the configuration data in step 1510. In step 1520, the data Configuration settings are typically placed on the device before the device is activated in 1530. In 1540, when the device begins operation, the processing system 2 uses the configuration data to selectively activate features, either, for example, by control of the instruction load, or selectively activating instructions integrated in the processing system 2 or the controller 19.

This can be achieved in one of two ways. For example, the configuration data could consist of instructions, such as software or firmware, that when applied through the processing system 2 cause the function to be implemented. Thus, for example, this process can be used to update the operation of the firmware provided in the second processing system 17, the processing system 10 or the controller 19 to allow additional functionality, improving the measurement algorithms, or the like, to implement.

5

10

fifteen

twenty

25

30

35

40

Four. Five

fifty

55

60

65

Alternatively, the configuration data can be in the form of a list of features, with this being used by the processing system 2 to access instructions already stored in the measuring device 1. The use of the configuration data, in this way , allows the measuring device to be loaded with a series of additional features, but non-operational features, when the device is sold. In this example, by updating the configuration data provided in the measuring device 1, this allows these new features to be implemented without the need to return the measuring device 1 for modification.

This is particularly useful in the medical industry, as it allows additional features to be implemented when the function receives approval for its use. Thus, for example, techniques may be available for the measurement or detection of lymphedema in a predetermined manner, such as through the use of a particular analysis of measured or similar voltage signals. In this case, when a device is sold, the approval may not have been obtained from an administering agency, such as Therapeutic Goods Administration, or the like. Consequently, the feature is deactivated through proper use of the configuration data. When the measurement technique subsequently obtains approval, the configuration data can be modified by loading new updated configuration data for the measuring device, which allows the feature to be implemented.

It will be appreciated that these techniques can be used to implement any of a number of different characteristics, such as different measurement techniques, analysis algorithms, reports on the results of the measured impedance parameters, or the like.

An example of a suitable system for providing updates will now be described with respect to Figure 16. In this example, a base station 1600 is coupled to a number of measuring devices 1, and to a number of terminal stations 1603 across a network. of communications 1602, such as the Internet, and / or through communications networks 1604, such as local area networks (LAN), or wide area networks (WAN). The end stations are in turn coupled to the measuring devices 1, as shown.

In use, the base station 1600 includes a processing system 1610, coupled to a database 1611. The base station 1600 operates to determine when updates are required, selects the devices to which the updates are applied, generates the configuration data and thus provides for the updating of the devices 1. It will be appreciated that the processing system 1610, therefore, can be a server or the like.

This allows the configuration data to be loaded from the server, or to the final station of a user 1603, such as a desktop, laptop, Internet terminal or the like, or alternatively allows the transfer from the server through the communications network 1602, 1604, such as the Internet. It will be appreciated that any suitable communication system can be used as wireless links, Wi-Fi connections, or the like.

In any case, an example of the process of updating the measuring device 1 will now be described in more detail with reference to Figure 17. In this example, in step 1700, the base station 1600 determines that there is a change in the state of regulation of features implemented within a certain region. As mentioned earlier this could happen, for example, after the approval by the TGA of new features.

The base station 1600 uses the change in the regulation state to determine the new features available in step 1710, before determining an identifier associated with each measuring device 1 to be updated in step 1720. As the changes in regulatory approval are specific to the region, this is usually achieved by accessing the database 1611 of the 1600 base station, including details of the regions in which each measurement device sold is used. The database 1611 includes the identifier for each measuring device 1, thus allowing to determine the identifier of each measuring device to be updated.

In step 1730, the base station 1600 determines the existing configuration data, usually from the database of 1611, on the one hand, one of the measuring devices 1, before modifying the configuration data to be put into operation. practice the new features in step 1740. The configuration data is then encrypted using a key associated with the identifier. The key can be formed from a unique prime number associated with the serial number, or partially derived from the serial number, and is normally stored in the 1611 database, or generated every time the use of a predetermined algorithm is required. .

In step 1760, the encrypted configuration data is transferred to the measuring device 1 as described above.

In step 1770, when the device is restarted and the first processing system 10 is activated, the first processing system 10 determines the encryption key, and uses it to decrypt the configuration data. This can be achieved in any one of a number of ways, such as by generating the key using the serial number or other identifier, and a predetermined algorithm. Alternatively, this can be done.

5

10

fifteen

twenty

25

30

35

40

Four. Five

fifty

55

60

65

achieved by accessing a key stored in memory 21. It will be appreciated that any form of encryption can be used, although typically strong encryption is used, in which a secret key is used to encrypt and decrypt the configuration data, to avoid the fraudulent alteration of the configuration of the users, as will be explained in more detail below.

In step 1780, the first processing system 10 activates software features within the second processing system 17 using the decrypted configuration data.

Therefore, it will be appreciated that this provides a mechanism for automatically updating the features available in the measuring device. This can be achieved by having the second processing system 17 receive the firmware from the processing system 10, or by activating firmware already installed in the second processing system 17, as described above.

As an alternative to performing this automatically, when the additional features are approved for use, the process can be used to enable the features to be activated upon payment of a fee. In this example, a user can buy a measuring device 1 with limited functionality implemented. By paying a fee, then additional features can be activated when required by the user.

In this example, as shown in Figure 18, when the user selects an inactive feature in step 1800, the first processing system 10 will generate an indication that the function is not available in step 1810. This allows the user to select an activation option in step 1820 which, in general, asks the user to provide the payment details in step 1830. Payment data is provided to the device manufacturer in some way and may involve having the user's phone number. device manufacturer, or enter the data through an appropriate payment system provided through the Internet or the like.

In step 1840, once payment is verified, the process can proceed to step 1720 to allow an automatic update that is provided in the form of a set of appropriate configuration data. However, if payment details are not verified, the process ends in 1850.

It will be appreciated by a person skilled in the art that the encryption of the configuration data using a unique identifier means that the configuration data received by a measuring device 1 is specific to that measuring device. Consequently, the first processing system 10 can only interpret the content of a configuration data if they are encrypted and decrypted using the correct key. Consequently, this prevents users from exchanging configuration data, or attempting to re-encrypt a decrypted file for transfer to a different device.

It will be appreciated that, in addition to, or as an alternative to simply specifying the features in the configuration data, it may be necessary to load additional firmware for the second processing system 17. This can be used, for example, to implement features that are not can be implemented using the firmware supplied with measurement device 1.

In this example, it is typical for the configuration data to include any firmware required to be loaded, which allows this to be loaded into the second processing system 17, using the first processing system 10. This firmware can then be automatically implemented. , or applied in accordance with the list of available features provided in the configuration data.

It will be appreciated that this provides a mechanism for selectively updating and / or activating or deactivating features such as measurement protocols, impedance analysis algorithms, reports of interpretation of the measured results, or the like. This can be done to ensure that the measuring device conforms to existing FDA or TGA approvals, or the like.

Case

To provide a housing configuration with electrical insulation suitable for the subject, an arrangement similar to that shown in Figure 19 can be used.

In this example, the measuring device 1 is provided in a housing 70 that includes a touch screen 71, which forms the I / O device 22, together with three respective circuit boards 72, 73, 74. In this case, the electronics digital, including the second processing system 17 and the first processing system 10 are provided on circuit board 72. Circuit board 73 is an analog circuit board and includes ADCs 37, 38 and DAC 39. Then , an independent power supply plate 74 is provided. The power plate typically includes an integrated baton, allowing the measuring device 1 to form a portable device.

5

10

fifteen

twenty

25

30

It is also typical, an electrical / magnetic shielding housing of the external environment and, consequently, the housing is typically formed of a mu-metal, or of aluminum with magnesium added.

Those skilled in the art will appreciate that numerous variations and modifications will be apparent.

Thus, for example, it will be appreciated that the features of different previous examples can be used interchangeably where appropriate. In addition, although the above examples have focused on a subject such as a human, it will be appreciated that the device and the measurement techniques described above can be used with any animal, including, but not limited to, primates, farm animals, animals performance, such as racehorses, or the like.

The processes described above can be used for the diagnosis of the presence, absence or degree of a number of conditions and diseases, including, but not limited to edema, lymphoedema, body composition, or the like.

It will also be appreciated that the techniques described above, such as electrode identification, device updates and the like can be implemented using devices that do not use the first separate processing system 10 and the second processing system 17, but rather use a single system of processing 2, or use some other internal configuration.

In addition, the final station 1603 can effectively carry out one or more of the tasks performed by the first processing system 10 in the examples throughout the specification. Accordingly, the device could be provided without the first processing system 10, with the functionality generally performed by the first processing system 10 performed by a final station 1603. In this arrangement, the final station 1603 effectively forms, therefore , part or all of the first processing system 10. This allows the measuring device 1 to be provided including only the second processing system 17 coupled directly to the external interface 23, to allow the measuring device 1 to be controlled by the final station 1603. Normally, this is achieved through the use of appropriate application software installed in the final station 1603.

Claims (23)

5 10 fifteen twenty 25 30 35 40 Four. Five fifty 55 60 65 1. An impedance measurement apparatus, for performing impedance measurements on a subject, including the apparatus: a) an input device (22), to receive input commands from an operator, b) a first processing system (10), coupled to the input device, and c) a second processing system (17) coupled to the first processing system, in which the second processing system (17): (i) apply one or more signals to the subject through electrodes (13, 14); (ii) receives an indication of the one or more signals applied to the subject through electrodes (15, 16); (iii) receives an indication of one or more measurement signals through the subject; (iv) performs at least a preliminary process of the indications to thereby determine the impedance values, characterized by that d) the first processing system (10) includes a profile storage memory (21) representing predetermined impedance measurement procedures, in which the first processing system (10): i) determines one of the impedance measurement procedures in accordance with the input commands received by the input device (22) of an operator; Y, ii) select instructions corresponding to the measurement procedure of the determined impedance; Y e) the second processing system (17) includes a programmable module (36) controlled by the selected instructions, in which the second processing system (17): (v) generates, using the instructions, the control signals that are used to apply one or more signals that implement the determined impedance measurement procedure to the subject; Y (iv) carry out, using the instructions, at least preliminary processing of the indications to allow the impedance values to be determined in this way. 2. Apparatus according to claim 1, wherein the apparatus is adapted to transfer the instructions from the first processing system to the second processing system. 3. Apparatus according to claim 1 or claim 2, wherein the apparatus is adapted to select the instructions using the configuration data. 4. Apparatus according to claim 3, wherein the apparatus is adapted to receive the configuration data of a remote processing system. 5. Apparatus according to any one of claims 1 to 4, wherein the instructions are in the form of at least one of: a) firmware; Y, b) integrated systems. 6. Apparatus according to any one of claims 1 to 5, wherein the second processing system is an FPGA. 7. Apparatus according to any one of claims 1 to 6, wherein the control signals represent a predetermined sequence of electrical signals, the sequence being dependent on the type of impedance measurement selected. 8. Apparatus according to any one of claims 1 to 7, wherein the apparatus includes: a) a current ADC for: i) receive signals from a current circuit; Y, ii) provide the indication of the one or more signals applied to the subject to the second processing system; Y, b) a tension ADC for: i) receive signals from a voltage circuit; Y, 5 10 fifteen twenty 25 30 35 40 Four. Five fifty 55 60 65 ii) provide the indication of the one or more signals measured from the subject to the second processing system. 9. Apparatus according to claim 8, wherein the apparatus includes at least one buffer circuit for: a) receive voltage signals from a voltage electrode; b) filter and amplify the voltage signals; Y, c) transfer the filtered and amplified voltage signals to the voltage ADC through a differential amplifier. 10. Apparatus according to claim 8 or claim 9, wherein the apparatus includes a current source circuit for: a) receive one or more control signals; b) filter and amplify the control signals to generate one or more current signals; c) apply the current signals to a current electrode; Y, d) transfer an indication of the signals applied to the current ADC. 11. Apparatus according to any one of claims 1 to 10, wherein the apparatus includes a control signal DAC for: a) receive the control signals from the second processing system; Y, b) provide analog control signals to a current circuit to make one or more current signals apply to the subject in accordance with the control signals. 12. Apparatus according to any one of claims 1 to 11, wherein the second processing system is formed from a first and second portions of the processing system, which are electrically shielded to thereby electrically isolate the subject from the first processing system of the first and second portions of the processing system. 13. Apparatus according to any one of claims 1 to 12, wherein the apparatus includes: a) a measuring device that includes at least the first processing system; Y, b) one or more subject units, including each subject unit at least part of the second processing system. 14. Apparatus according to any one of claims 1 to 13, wherein the apparatus includes at least two current electrodes for the application of current signals to the subject, and a switch connected to the current electrodes for discharge of the subject before of the measurement of induced stress. 15. Apparatus according to any one of claims 1 to 14, wherein the apparatus includes a housing having: a) a screen; b) a first circuit board for mounting at least one of the processing systems; c) a second circuit board for mounting at least one of an ADC and a dAC; Y, d) a third circuit board for mounting a power supply. 16. Apparatus according to claim 15, wherein the housing is formed from at least one of a mu-metal and aluminum with magnesium added, to thereby provide an electric / magnetic shield. 17. Apparatus according to any one of claims 1 to 16, wherein the apparatus includes multiple channels, each channel being for impedance measurements using a respective set of electrodes. 18. Apparatus according to any one of claims 1 to 17, wherein the apparatus is adapted to: a) determining an electrode identifier associated with at least one electrode provided in the subject; b) determine, using the electrode identifier, an electrode position indicative of the position of at least one electrode on the subject; Y, c) perform at least one impedance measurement using the electrode position. 19. Apparatus according to any one of claims 1 to 18, wherein the apparatus is adapted to: a) determine a parameter associated with at least one electrode conductor; Y, b) have at least one impedance measurement made using the determined parameter. 5 10 fifteen twenty 25 30 35 40 Four. Five 20. Apparatus according to any one of claims 1 to 19, wherein the apparatus is adapted to: a) receive configuration data, the configuration data being indicative of at least one characteristic; b) determine, using the configuration data, instructions that represent the at least one characteristic; Y, c) make that, using the instructions, at least one of: i) at least one measurement of the impedance to be performed; Y, ii) at least one measurement of the impedance to be analyzed. 21. Apparatus according to any one of claims 1 to 19, wherein the apparatus is adapted to: a) have a first signal applied to the subject; b) determine at least one parameter relative to at least a second measurement signal across the subject; c) compare the at least one parameter with at least one threshold; Y, d) based on the results of the comparison, selectively repeating steps (a) to (d) using a first signal that has a greater magnitude. 22. A method of performing impedance measurements on a subject, including the method: a) receive input commands from an operator; b) use a second processing system coupled to a first processing system, to apply one or more signals to the subject through electrodes (13, 14); c) use the second processing system to receive an indication of the one or more signals applied to the subject through electrodes (15, 16); d) use the second processing system to receive an indication of one or more measurement signals through the subject; e) use the second processing system to perform at least preliminary processing of the first and second data to thereby allow the determination of the impedance values; characterized in that the method includes: f) using the first processing system (10) to determine a measurement procedure of the impedance of a memory (21) storing profiles representing predetermined impedance measurement procedures, in accordance with the input commands received; Y, g) use the first processing system (10) to select the instructions corresponding to the measurement procedure of the determined impedance; h) use the second processing system (17) to generate, following the instructions, the control signals that are used to apply one or more signals of implementation of the measurement procedure of the impedance determined for the subject; Y i) use the second processing system (17) to carry out, using the instructions, at least the preliminary processing of the indications to thus allow determining the impedance values. 23. A method according to claim 22, wherein the method is carried out using the apparatus according to any one of claims 1 to 21.