GB2093218A

GB2093218A - A Respirator for Clinical Use

Info

Publication number: GB2093218A
Application number: GB8125980A
Authority: GB
Original assignee: MEDICAS MANUF
Current assignee: MEDICAS MANUF
Priority date: 1981-02-17
Filing date: 1981-08-26
Publication date: 1982-08-25
Also published as: GB2093218B; FR2499850B1; JPS57139341A; DE3133697A1; FR2499850A1; ES8201825A1; SE446064B; SE8105776L; ES499506A0; CA1202224A

Abstract

A respirator comprises a pneumatic module and a control module 6. The pneumatic module comprises manifolds 2-4, connected to supplies of compressed gases, and to a pneumatically operated pressure equilibrator 21 which is connected to a mixing chamber 22, controlled by a dual pressure switch 26, which supplies batteries of valves 7, 16 having stepped series-connected resistances signalling the control module 7. Battery 7 forms an inspiration valve assembly and incorporates a flow transducer 15, while the other controls the expiration valve 7. The control module 6 comprises a microprocessor 35 incorporating a keyboard 38 and a VDU40 simultaneously showing alpha- numeric and graphic information. The information to the control module 6 from the pneumatic module passes through amplifying blocks 42, 43, 44 and A/D converters which are connected to buses of the microprocessor 35. The data buses are also connected to a plurality of optical couplers and amplifiers 46 to 49 which produce signals for controlling the various valves and members of the pneumatic module. <IMAGE>

Description

SPECIFICATION Improvements Introduced in a Respirator for Clinical Use The present invention relates to improvements introduced in a respirator for clinical use.

The respirator made in accordance with the improvements of the instant invention can be universally used having a maximum utility in adult, child and new-born infant intensive care and resuscitation units, which can be used in all the phases and modalities of treatments with artificial ventilation, and having the important advantage that all the accessories normally used in this type of treatments are integrated, forming part of the basic equipment which, in practice, forms the respirator.

The improved respirator, object of this invention, basically comprises two main modules which will hereinafter be referred to as: Pneumatic Unit General Control Module The general control module contains a microprocessor, preferably of 8 bits, including all its accessory and peripheric circuits, this microprocessor being controlled by various pneumatic and electromechanical controllers from a plurality of data proportioned by the appropriate sensors arranged throughout the pneumatic unit. This control takes place following the programmed instructions registered in permanent memories cooperating with the microprocessor.As the intercommunicating element between the operator of the respirator and the general control module, there is provided a key-board which permits data and instructions to be introduced and a cathode-ray screen capable of simultaneously reflecting alphanumerical data and graphic representations, by means of which the performance and effectiveness of the respirator is highly improved when compared with conventional respirators.

The pneumatic unit,. in turn, comprises the respective manifolds for supplying gases compressed at the pressures normally used in hospitals, as well as a mixer and a mixing chamber to proportion the patient with the appropriate amount of gases, and a plurality of valves, flow transducers, pressure regulators, etc., all of which are duly interrelated with the control module to transmit and receive the adequate information which permits the complete automization of the respirator.

More specifically, the pneumatic unit comprises: a) a gas mixer b) a mixing chamber c) an inspiration valve d) an oxygen analyzer e) a flow transducer f) a system for controlling an expiration valve g) an expiration valve h) a system for measuring the patient's pressure i) measuring and safety systems.

All these members, as previously mentioned, are duly interrelated through the corresponding optical couplers, analyzers, sensors, or other element to the general control module which is controlled by a main processing unit based on a microprocessor.

The supply of gas proportions the gaseous mixture to be supplied to the patient, regulating the composition and pressure thereof with the help of a gas mixer. The gas mixer makes the air/02 or OJN2O mixture from the corresponding gases under pressure which reach same through the suitable manifolds, the process used preferably consisting in controlling the relative times of the passage of each gas through the same fixed resistance. In this respect, it should be pointed out that the preferred embodiment uses the time controlled mixer, object of Spanish Utility Model 23 1,608.

The mixing chamber serves as a gas accumulator so that elevated instantaneous flows are obtained, besides permitting the homogenization of the mixture of gases.

From the mixing chamber there protrudes a manifold which reaches a battery of valves forming the assembly of the inspiration valve. This inspiration valve comprises the end controller of the servo-system which regulates the rate of inspiration to the patient, depending on the signal transmitted thereto by the flow transducer and on the instantaneous value necessary at each moment. The practical realisation of this inspiration valve is, as previously mentioned, a battery of valves with a digital stepping.

Inserted in the manifold which supplies the mixture of gases to the patient, there is a flow transducer, an element which permanently sends information to the general control. This transducer has a bidirectional character, it has a low charge loss and a rapid reply.

The expiration valve consists of a pneumatically operated membrane valve. The election of the pneumatic operating system is preferred due to the simplicity reliability and lightness thereof.

The pneumatic controller of the expiration provides the pneumatic signals for the control of the expiration valve, depending on the electrical signals received from the general control. It uses O, or compressed air as the pneumatic supply.

The system for measuring the patient's pressure is formed of a pressure transducer and an electrically controlled three-way valve which permits the transducer to be periodically placed in communication with the atmosphere, to automatically measure same.

Finally, there are various elements, such as pressure switches, filters, and unidirectional safety valves which function as auxiliary measuring, controlling and safety elements.

With respect to the general control module, it can be said that same monitors all the elements of the system depending on the input signals, so that the functions requested and which are contained, in a programmed manner, in the memories incorporated therein are carried out.

As the main active members, there is an 8 bit microprocessor provided with its corresponding RAM and ROM memory blocks, as well as its various connected circuits such as output-input units, drivers, etc.

The programs regulating and controlling the operation of the assembly are structured as clearly delimited functional blocks, so that the writing of said programs is facilitated, a maximum utility being made of the flexibility of the microprocessor, besides, conserving the possibility of including new functions at a later date or, of adapting the existing functions to specific needs of any particular applications.

For the introduction to the microprocessor of digital data and controls, there is used a keyboard which, in the preferred embodiment of the respirator, comprises keys for digits, keys for introducing parameters, and keys for selecting the different functions.

The microprocessor includes various routines to verify parameters, monitoring the validity of the data introduced, both with respect to the number and combination thereof and to the absolute values of the digital data introduced, circumstances which minimises the possibility of an erroneous use of the respirator.

Furthermore, the respective edition programs for the reflection on a cathode ray screen of different informations, both alpha-numerical and graphic, are included, this fact facilitating and proportioning the respirator thus constructed with a great versatility.

The capacity of the microprocessor to effect arithmetic operations, permits the following parameters and variables to be computed: Maximum alveolar pressure, resistance, correction of volumes, expiration pressures, representation of curves, etc.

Besides, the respirator is capable of reflecting on the screen the curves which would be the result of applying new respiratory conditions to the patient being treated. This simulation can be effected while ventilation continues with the preestablished parameters and only in the event that the new values are satisfactory, can the operator request the change in the ventilation of the patient, whose control is carried out by the microprocessor which the new parameters computed during simulation.

Another characteristic of this respirator resides in its capacity to effect a "clinical history". Hence, reserving a certain portion of the memory for storage, the values of the measured parameters of the patient during the final hours can be accumulated therein. A simple comparison of each new value with the prior, automatically made value or values gives a clear idea of the tendency in the clinical evolution of the patient.

Likewise, there can be established advice or alarm conditions when certain absolute values are surpassed or variations are produced.

In short, the possibilities of the respirator which is controlled by the microprocessor and, in short, by the control programs thereof, are practically unlimited and eliminates monitoring on the part of the operator presently required by conventional respirators.

To complement the description which will subsequently be made and for a better understanding of the characteristics of the invention, a drawing is attached to this specification, forming an integral part thereof, wherein illustratively and not limiting there is represented the general scheme of the respirator in which the pneumatic unit and the general control module are clearly delimited. Referring to the general scheme of the figure, the manifolds 2, 3 and 4 which contain nitrogen protoxide, oxygen and compressed air, respectively, are provided with the corresponding pressure switches 18, 193 and 19b, a hand operated pressurer reducer 20 being joined to all the manifolds, which reducer pressure produces a reference pressure for the operation in the pressure equilibrator 21.

This pressure equilibrator 21, which is pneumatically operated as previously mentioned, guarantees that the pressure of the two gases to be mixed, oxygen and air or oxygen and nitrogen protoxide, is the same.

The pressure equilibrator 21 communicates with the mixing chamber 22 through the corresponding valve 23 to provide air/N20 and valve 24 to provide 02, which valves reach a common resistor 24. The mixing chamber 22 permits the homogenization of the mixture of gases and serves as a reducing reserve of the variations in pressure in the supply of the expiration valve 7. Filling of the mixing chamber 22 is controlled by the highly sensitive dual pressure switch 26, which acts on the different valves of the mixer. Likewise, a safety valve 27 is incorporated which insures that the operating pressure of the mixing chamber 22 will, in no event, be surpassed.

Besides, there is an 02 analyzer 28 which, through valve 29 and its associated resistor 30, permits a sample of the gas contained in the mixing chamber 22 to be taken, analyzing it and thus verifying the corresponding functioning of the mixer. Measuring of this oxygen analyzer 28 can be verified and corrected by cutting off the passage of gas from the mixing chamber 22 and allowing the necessary time to lapse so that the gas contained in the measuring chamber is only air.

The inspiration valve 7, besides communicating with the mixing chamber 22, converges in the flow transducer 1 5 of the patient's block, which instantaneous flow trasducer is directional and is located close to the patient in the section common to the inspiration and the expiration. This transducer 1 5 is joined to a block 31 which conditions the signal transmitted by the transducer 15 and through line 32 sends it to the general control module 6.

A pressure transducer 11 is also connected to the patient's circuit, through the three-way valve 33, which structure permits same to communicate with the atmosphere and to verify and correct those deviating from the zero of the scale thereof.

The resipiration valve 14 is pneumatically controlled and can be closed completely or partially, a fact which permits continuous positive pressures to be generated during the expiration phase. This valve 14 is controlled by a battery of valves with a resistance determining the block 16 which controls the final pressure, which permits a variable pressure to be generated which, applied to the control of the valve 17, produces the closure or the desired pressure in the patient's circuit.

All these members are controlled by the general control block 6 which comprises a microprocessor 35, preferably having 8 bits, which through the various buses thereof communicates with the remaining elements of the control module, inter alia, the block or ROM storage memory 36 and the block or RAM storage memory 37.

The data, controls and functions are introduced by the keyboard 38 which is connected to the microprocessor 35 through the corresponding interphase and modification unit 39 thereof, while the visual representation of the alpha-numeric or graphic information takes place on a cathode ray screen 40 connected to the microprocessing system through the corresponding screen refreshing unit 41 thereof.

The blocks 42, 43 and 44 correspond to amplifier blocks and analog/digital converters which receive, respectively, the signals from the signal conditioner 31 of the flow transducer 1 5, from the pressure transducer 11 and from the 02 analyzer 28, the signals originating from the various sensors arranged throughout the respirator reaching the block 45 which comprises a a plurality of level detectors.

Blocks 46, 47, 48 and 49 comprise output phases by optical couplers and amplifiers for the signals which, originating from this control block 6, control the operation of the respirator, the outputs of these blocks being referenced with the reference of the device to which they are joined, the output block 49 being reserved to transmit signals to other operating members having a minor functional importance.

From this scheme of the general control block there has been eliminated the supply which, under normal conditions, should be connected to the electrical network, electrical batteries having been provided which are capable of guaranteeing the automatic functioning of the assembly for a determined period of time in the absence of electrical power in the supply.

Thus, a program controlled respirator, which is capable of effecting a wide range of functions and modes of operation, discarding the human operator presently required by this type of device, is consolidated.

Claims

1. Improvements introduced in a respirator for clinical use, essentially characterised in that the respirator is comprised of a pneumatic module and a control module, interdependently coupled to each other, the pneumatic module comprising members to be connected to supplies of compressed gases which reach a pneumatically operated pressure equilibrator which is connected to a mixing chamber controlled by a dual pressure switch from which there protrude two main manifolds which supply batteries of valves with series-connected resistances, one of which batteries determines an inspiration valve assembly, while the other determines a control valve battery for the expiration valve, the former feeding the patient's circuit and incorporating a flow transducer, the control module being connected to the pneumatic module by means of information lines and control lines, said control module being constituted by a microprocessor incorporating a keyboard for the acquisition of data and instructions and a cathode ray screen capable of simultaneously reflecting alpha-numeric and graphic information, the keyboard and the screen being connected to the microprocessor through the corresponding interphase units thereof, the information lines which join the control module to the pneumatic module reach a plurality of amplifying blocks followed by corresponding analog/digital converters, all connected to the buses of the microprocessor which data buses are connected also to a plurality of optical couplers and amplifiers which produce signals capable of controlling the various valves and members of the pneumatic module.

2. Improvements introduced in a respirator for clinical use according to Claim 1, characterised in that the pneumatic module is provided with a pressure transducer connected to the patient's circuit through a threeway valve, one of the ways communicating with the atmospheric pressure, and the valve being controlled by the control module to permit the periodic and automatic measuring of the pressure transducer.

3. Improvements introduced in a respirator for clinical use according to Claim 1, characterised in that the control module receives a line of information coming from an 02 analyzer, which is connected through a valve and its corresponding resistance to the mixing chamber, the control module including a program of evaluation and analysis of the functioning of the gas mixer so that the periodic and automatic auto-measuring is obtained.

4. Improvements introduced in a respirator for clinical use according to Claim 1, characterised in that the flow transducer is bidirectional and is located close to the patient in the section common to the inspiration and expiration, sending a signal to a conditioning block which is connected to an information line of the control module.

5. Improvements introduced in a respirator for clinical use according to Claim 1, characterised in that the control module has recorded in a memory a program which enables the respirator to operate in all the possible assisted and controlled modes of respiration, as well as variations and combinations.

6. Improvements introduced in a respirator for clinical use, according to Claims 1 and 5, characterised in that the control module has recorded in a memory a program of simulation of the reply which will be obtained in the clinical variables of the patient as a result of the change of the operating parameters controlled, in this moment, by the respirator and which simulation of reply is obtained on the cathode ray screen without producing variation in the actual operating parameters.

7. Improvements introduced in a respirator for clinical use according to Claims 1, 5 and 6, characterised in that the cathode ray screen presents, in the form of stable curves, the curves corresponding to pressure, volume and instantaneous flow, which relative data are temporarily stored in a memory controlled by the controller inherent to the screen.

8. Improvements introduced in a respirator for clinical use according to Claims 1,5,6 and 7, characterised in that the control module has a determined memorizing zone for accumulating the different clinical parameters of the patient for a certain period of time in order to form a data bank or clinical history of the patient.

9. Improvements introduced in a respirator for clinical use according to Claims 1, 5, 6, 7 and 8, characterised in that the control module has recorded in a memory a program which controls the keys of the keyboard, so that this should always be operated in a defined sequential manner, simultaneously checking the proposed values following certain computered patterns, not permitting the proposed parameters which may lead to erroneous combinations or abnormal values thereof to be accepted by the machine.

10. Improvements introduced in a respirator for clinical use according to Claims 1, 5, 6, 7 and 8, characterised in that the control module has permanently registered in a memory, certain basic operating parameters which the equipment proposes to the operator at the initial moment of the connection thereof.

11. A respirator for clinical use substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.