WO2001017432A1

WO2001017432A1 - Improvements in or relating to ultrasound devices

Info

Publication number: WO2001017432A1
Application number: PCT/GB2000/003461
Authority: WO
Inventors: Mark Graham Blunden
Original assignee: Deltex (Guernsey) Limited
Priority date: 1999-09-09
Filing date: 2000-09-08
Publication date: 2001-03-15
Also published as: AU7026000A; GB9921348D0

Abstract

The present invention describes an ultrasound probe (5) for a haemodynamic monitor, the probe containing ultrasound transmit and receive crystals (10) and an additional transducer (11) to measure a further physiological parameter in the region of the probe. Output data from the transducer (11) is preferably digitised close to its source and fed back to the system processor (7) via a communications bus provided to pass data between the probe and the processor.

Description

"IMPROVEMENTS IN OR RELATING TO ULTRASOUND

DEVICES"

Field of the Invention

This invention relates to an ultrasound device and, in particular, to a disposable ultrasound probe insertable into a body cavity to enable ultrasound insonation of internal vessels and organs. Aspects of the invention may, however, be applied to other non-invasive ultrasound devices such as those which are placed in contact with the body outer surface.

Background

Ultrasound is widely used in medicine for imaging and /or diagnostic purposes. In one form of device, ultrasound transmit and receive crystals are mounted on the tip of a probe which, in use, is located within the body so that specific organs or vessels can be subjected to ultrasound insonation and the reflected signals then analysed to give particular diagnostic information. In another form of device, the transmit and receive crystals are mounted in contact components designed to be held in contact with the body outer surface in a position adjacent the organs or vessels to be insonated.

This company has, for some time, been manufacturing and selling an instrument for determining cardiac function. This instrument incorporates a disposable probe which is inserted into the patient's oesophagus, the probe having mounted on the outer end thereof, ultrasound transmit and receive crystals. In use, the probe is aligned so that the crystals are aligned substantially at 45° to the patient's descending aorta and are thus arranged to insonate a section of the descending aorta with ultrasound.

Invariably, clinicians need to monitor other parameters whilst monitoring cardiac output, or could at least gain additional useful knowledge about the patient from so doing. This presently requires the use of separate equipment and it is difficult, if not impossible, to measure parameters at the same site as the location of the ultrasound transducers.

It is therefore an object of this invention to provide an ultrasound device which will go at least some way in addressing the above-mentioned drawback, or which will at least provide a useful choice.

Summary of the Invention

Accordingly, in one aspect, the invention provides a probe for a Doppler ultrasound haemodynamic monitor, said probe being locatable in the oesophagus of a patient and including:

at least one ultrasound transmit and receive transducer; and

a further transducer operable to measure a physiological parameter within the oesophagus during ultrasound isonation. Preferably said further transducer is operable to measure one or more physiological parameters selected from the group comprising blood pressure, temperature, pulse oxygenation and pH.

In a second aspect the invention comprises a Doppler ultrasound haemodynamic monitor including a probe as hereinbefore set forth;

a processor to generate transmit signals for said probe and to receive and process received signals from said probe,

said monitor further including a communications bus, external to said processor, to enable the transmission of data between said further transducer in said probe, and said processor.

Preferably said probe includes a memory device to store patient and probe use details, said memory device and said further transducer communicating with said processor via a common communications bus.

Preferably said communications bus comprises an I²C bus.

In a third aspect the invention provides a method of passing data between a transducer located on an oesophageal probe and a processor operable to process data from said transducer, said method comprising digitising said data and conveying the same to said processor, via a communications bus. Preferably said oesophageal probe includes a memory device communicable with said processor to store patient and/ or probe use information, said method including passing data between said memory device and said processor, and between said transducer and said processor, on a common communications bus.

Many variations in the way the present invention can be performed will present themselves to those skilled in the art. The description which follows is intended as an illustration only of one means of performing the invention and the lack of description of variants should not be regarded as limiting. Wherever possible, a description of a specific element should be deemed to include equivalents thereof whether in existence now or in the future. The scope of the invention should be limited by the appended claims alone.

Brief Description of the Drawings

One form of the invention will now be described with reference to the accompanying drawings in which:

Figure 1 : shows a schematic system outline of a Doppler ultrasound cardiac output monitor incorporating an ultrasound probe according to the invention;

Figure 2: shows a plan view of an ultrasound probe according to the invention; Figure 3: shows a schematic outline of the electronic components included in the probe shown in Figure 2;

Figure 4: shows a schematic outline of certain electronic components incorporated in a patient interconnect cable and arranged to operate in conjunction with the components shown in Figure 3; and

Figure 5: shows a schematic circuit block outline for adding data from a further transducer into a haemodynamic monitor according to the invention.

Detailed Description of Working Embodiment

Referring to the drawings, the present invention provides an ultrasound transmit and receive device for use in conjunction with a host processor to provide diagnostic and /or imaging data derived from a human subject. Whilst such a device could be adapted for contacting the body outer surface, the following description is directed to a probe 5 insertable into a human body cavity (not shown) .

The particular form of probe herein depicted and described comprises a disposable oesophageal catheter or probe for use in a Doppler ultrasound haemodynamic monitor. In this application, the probe is connected to a host system processor 7 which causes the probe 5, when located in a patient's oesophagus, to emit ultrasound in the direction of the descending aorta, and to receive signals reflected off red blood cells moving through the aorta. The ultrasound signals are then processed to give a measure of blood velocity. Details of patient weight, height and age are also processed within the host system processor, according to an accepted statistically based method, to give a measure of aorta cross section, the resulting measure of cross section then being combined with blood velocity to give an indication of cardiac function. Such a form of probe is described in greater detail in our pending British Patent Applications 9908425.3 and 9908427.9 filed on 13 April 1999.

In the form of apparatus shown in Figure 1 , a haemodynamic monitor includes a probe 5 connected to the host system processor 7 through a patient interconnect cable (PIC) 9, all the components having electronic components which will be described, at least in part, below. In accordance with this invention, the probe 5 not only includes ultrasound transmit and receive transducers 10, but also a further transducer 1 1 to monitor a further physiological parameter within the patient, in the area adjacent the low end of the probe when positioned within the patients oesophagus. The further transducer may, for example, be configured to measure temperature, pulse oxygenation and /or pH.

As is described in greater detail in British Patent Application

9908427.9 mentioned above, the probe 5 is preferably provided with a memory device 23 (Figure 2) which communicates with the processor 7, via an in-built communications bus, to store data pertaining to patient and probe use. In accordance with the preferred embodiment of this invention, data from the further transducer 11 is passed back to the processor via the same communications bus.

Referring now to Figure 2, in the conventional manner, the probe 5 comprises a flexible elongate shaft member 12, at the free end of which the transducers 10 and 1 1 are mounted, the transducers being covered by a soft plastics or rubber boot 13. The opposite end of the shaft 12 carries a connector 15 whereby the probe may be connected into the host system processor 7, in this case via the PIC 9. Whilst, for illustrative purposes, the further transducer 1 1 is shown mounted adjacent the ultrasound transducers 10, it will be appreciated that the transducer 1 1 could be placed anywhere along the length of the probe that intentionally comes into contact with the patient. In reality, the precise positioning of the transducer 1 1 will depend on application, the parameter to be measured, convenience of assembly, and practicality. For example, if the transducer 11 was intended for temperature measurement it would be unwise to position the same too close to the ultrasound crystals 10, as the crystals 10 generate a small amount of heat during operation which could give affect the measurement generated by the transducer 1 1.

As described above and in greater detail in British Patent

Application 9908427.9, the probe 5 has embodied therein, an electronic memory which can receive and store probe /patient use parameters. Some parameters may be entered into memory in manufacture whilst others will be inserted when the probe is connected to the host system processor 7.

In the form shown in Figures 2 and 3, the electronic memory is embodied in the connection 15 between the probe 5 and the PIC

9. More particularly the connection 15 is preferably defined, in part, by a printed circuit board 17, edge part 19 of which projects to form a connection with the PIC 9, and part 21 of which is enveloped in an insulating cover 22. The electronic memory, preferably in the form of an E PROM 23, is mounted on the printed circuit board 17.

The PIC 9 obviously provides an electrical and data connection with the host system processor 7 and may include pre- amplification means to amplify the signals from the transducers 10 and 1 1 before transmission back to the host system processor 7.

Turning now to Figures 3 and 4, the probe 5, PIC 9 and system processor 7 incorporate an industry standard communications bus, in this case a Philips PC bus, to allow data to be passed there between. To this end, connector edge part 19 on the probe connector 15 includes pins SDA and SC for the serial data and serial clock lines respectively. These engage with the corresponding SDA and SCL pins on the PIC 9 and lead back to the host system processor, to enable communication between the host system processor 7 and the E²PROM 23. Device Cl is provided to decouple the power rail to the E²PROM 23. Pin PP on the probe contacts corresponding PP on the PIC 9 (Figure 4), the PP connection on the PIC 9 serving not only to indicate when a probe is connected to the PIC 9 but also, to release the SDA line for the passage of data between the processor 7 and the probe 5. More particularly, and with reference to Figure 4, when there is no probe present, Ql , R7 and C7 hold the SDA line low at just over 0 volts. When a probe is present, PP on the PIC 9 is held low (connected to ground) and Q 1 , R7 and C7 release the SDA line to pass data. Thus the SDA line provides the dual function of passing data and indicating the connection, or not, of a probe.

PIC 9 receives power at 5 volts from the host processor 7 and uses this power to power E²PROM 23, but includes components R6,C6 (25) to filter out noise induced in the PIC cable.

Referring now to Figure 5, the probe 5 may include up to n additional transducers 1 1. However many such transducers are, in fact, included, analogue outputs therefrom are conditioned at 26 and then converted into digital form at 27 before being passed to the processor 7 via the PC bus. The signal conditioning and analogue to digital conversion could be undertaken in the probe connection 15 by components added to circuit board 17. However, it is more likely that the components used to undertake processes 26 and 27 would be included with that part of PIC 9 which mates with connection 15 as, unlike the probe 5, the PIC 9 is not intended as a disposable item. Whilst in the system described herein, the ultrasound transmit and receive signals are passed between the probe 5 and the processor 7 in analogue format, it is conceivable that these, also, could be digitised and also passed via the PC bus.

Thus, the combination of a probe having a plurality of transducers and in-built memory, and a PIC which, together with the probe has an industry standard communications bus, not only permits efficient functioning of the ultrasound facility but also enables clinicians to monitor physiological parameters in the region of the patient's body being isonated with ultrasound.

Claims

1) A probe for a Doppler ultrasound haemodynamic monitor, said probe being locatable in the oesophagus of a patient and including:

at least one ultrasound transmit and receive transducer; and

a further transducer operable to measure a physiological parameter within the oesophagus during ultrasound isonation.

2) A probe as claimed in claim 1 wherein said further transducer is operable to measure one or more physiological parameters selected from the group comprising blood pressure, temperature, pulse oxygenation and pH.

3) A probe for a Doppler ultrasound haemodynamic monitor when constructed arranged and operable substantially as herein described with reference to the accompanying drawings.

4) A Doppler ultrasound haemodynamic monitor including a probe as claimed in any one of claims 1 to 3;

a processor to generate transmit signals for said probe and to receive and process received signals from said probe, said monitor further including a communications bus, external to said processor, to enable the transmission of data between said further transducer in said probe, and said processor.

5) A monitor as claimed in claim 4 wherein said probe includes a memory device to store patient and /or probe use details, said memory device and said further transducer communicating with said processor via a common communications bus.

6) A monitor as claimed in claim 4 or claim 5 wherein said communications bus comprises an PC bus.

7) A Doppler ultrasound haemodynamic monitor when constructed arranged and operable substantially as herein described.

8) A method of passing data between a plurality of transducers located on an oesophageal probe and a processor operable to process data from said transducers, said method comprising digitising said data and conveying the same to said processor, via a common communications bus.