GB2479984A

GB2479984A - Foetal blood sampling probe

Info

Publication number: GB2479984A
Application number: GB1106808A
Authority: GB
Inventors: Maria Smith; Stephen James Smith
Original assignee: Individual
Current assignee: Individual
Priority date: 2010-04-27
Filing date: 2011-04-21
Publication date: 2011-11-02
Anticipated expiration: 2031-04-21
Also published as: GB201007007D0; GB2479984B; GB201106808D0

Abstract

A two-part, hand held foetal blood sampling probe 2 enables rapid determination of foetal stress during labour. The two-part probe encompasses a sterile disposable sensing probe 6 containing a pH sensor 10 and lancet 8 attaching to a monitor 4 housing the hardware, software and user interface. The two parts 4 and 6 combine to form a small single foetal probe 2 capable of determining pH levels at small maternal cervical dilatations. The foetal probe may be used to determine analytes such as: pO2, pCO2, Na, Cl and K of a foetal blood sample. The reusable monitor may comprise lancet control means and a display for showing the resulting analysis of an analyte present in the blood sample. The disposable sensing probe may comprise a lancet to secure a blood sample from a foetal scalp, integral fluidics for transporting the blood sample for analysis and an integral sensor for effecting analysis and providing a result relating to an analyte present in the blood sample. The disposable sensing probe may also comprise integral heating means for maintaining the temperature of the blood sample at a desired level.

Description

Foetal Blood Sampling Probe The present invention is concerned with improvements in or relating to a blood sampling probe and is particularly concerned with improvements in a foetal blood sampling probe for determining the pH measurement of a foetal blood sample.

Known as a Foetal Blood Sample (FBS), the pH measurement of the blood during labour is an important diagnostic tool in the assessment of the state of well being of the foetus. The measurement is most often required to assess the need for curtailing labour.

An improved ability to determine foetal wellbeing would result in a lowering of Caesarean section rates. The National Guidelines (NICE) on Intrapartum care recommend that if there is a pathological foetal heart monitoring then an FBS should be taken.

Foetal blood sampling may be difficult to perform.

Problems that normally arise are: * the cervix needs to be at least 3 -4 cm dilated; * the presenting foetal part needs to be accessible during digital vaginal examination i.e. at least -2 in relation to the ischial spines; * difficult to obtain a continuous blood sample without any air bubbles; * the procedure is uncomfortable to women in labour in that, without an epidural, a large speculum needs to be inserted into the vagina in order to directly visualise the foetall head; * clotting of blood by the time the sample is taken to a bench-top blood gas analyser; * amount of sample required by blood gas analysers is frequently more than that which can adequately be obtained; * unreliability in readings as a result of the above; and, * unnecessary caesarean sections are conducted if an adequate blood pH cannot be obtained leading to additional morbidity to the mother and additional costs to the healthcare provider.

It is, therefore, an object of the present invention to provide an improved foetal probe that overcomes or at least mitigates the disadvantages met hitherto.

Therefore, the present invention conveniently provides a foetal probe comprising means for securing a foetal blood sample, characterised in that the foetal probe is a two-part assembly comprising a reusable monitor and a disposable sensing probe.

Preferably, the disposable sensing probe comprises: a) a lancet capable of coming into contact with a foetal scalp when the foetal probe is in use in order to secure a foetal blood sample; b) integral fluidics for transporting the foetal blood sample for analysis; and, c) an integral sensor assembly for effecting an analysis and providing a result relating to the analytes present in a foetal blood sample taken from a foetus when the foetal probe is in use.

Conveniently, the disposable sensing probe comprises integral heating means for maintaining the temperature of the secured foetal blood sample at a desired level.

In another preferred embodiment provided by the present invention, the disposable sensing probe also comprises calibration and quality control means for maintaining the accuracy of the analytical results obtained from the analyte when the foetal probe is in use.

In a further preferred embodiment provided by the present invention, the reusable monitor comprises: a) lancet control means for operation of the lancet when the foetal probe is in use; and, b) a digital display for showing the resulting analysis of the analyte present in the foetal blood sample taken from a foetus when the foetal probe is in use.

Preferably, the reusable monitor comprises functional controls for use when the foetal probe is in use for calibration and quality control of the foetal blood sample.

In another convenient embodiment the foetal probe comprises quick release means for connecting the reusable monitor and the disposable sensing probe so that, when used, a disposable sensing probe may be disconnected and replaced by an unused disposable sensing probe.

Preferably, the disposable sensing probe comprises means for delivering a flushing solution to facilitate cleansing of the disposable sensing probe between successive samples of foetal bloods.

Preferably, the reusable monitor comprises a power pack in the form of a rechargeable battery.

Conveniently, the foetal probe comprises communication means for wirelessly downloading information secured in relation to a foetal blood sample to peripheral monitors, hospital information systems, printers and a memory store relating to the foetus from whom a blood sample is secured and the foetal probe can be operated electrically, mechanically or electromechanically for determining, inter alia, the pH of the foetal blood sample.

Conveniently, the foetal probe may be used to determine analytes such as: p02, pCO2, Na, Ca, Cl and K of a foetal blood sample.

The present invention also provides a method of securing a foetal blood sample using a foetal probe according to any one of the preceding Claims, the method comprises the steps of: b) connecting a disposable sensing probe to a reusable monitor; c) inserting the disposable sensing probe end first into the vagina such that a positive seal is formed against the scalp of the foetus; and, d) activating a plunger of the reusable monitor to release a lancet of the disposable sensing probe whereby the scalp of the foetus is pierced and a blood sample is secured for analysis of the analytes as required.

Preferably, the present invention provides a reusable monitor for use with a foetal probe, the monitor comprising lancet control means for operation of a lancet, when the reusable monitor is in use and connected to a disposable sensing probe, the reusable monitor also comprising a display for showing the resulting analysis of an analyte present in foetal blood sample taken from a foetus when the foetal probe is in use and connected to a disposable sensing probe as aforesaid.

More conveniently, the monitor also comprises functional controls whereby, when the foetal probe is in use, for calibration and quality control of the foetal blood sample.

Preferably, the reusable monitor comprises a quick release means for connection to a disposable sensing probe so that, when used, a disposable sensing probe may be disconnected and replaced by an unused disposable sensing probe.

More preferably, the reusable monitor comprises a power pack in the form of a rechargeable battery, the reusable monitor further comprising communication means for wirelessly downloading information secured in relation to a foetal blood sample to peripheral monitors, hospital information systems, printers and a memory store relating to the foetus from which a blood sample is secured.

The present invention also conveniently provides a disposable sensing probe for use with a foetal probe, characterised in that the disposable foetal probe comprises: a) a lancet capable of coming into contact with a foetal scalp when the foetal scalp is in use in order to secure a foetal blood samples; b) integral fluidics for transporting the foetal blood sample for analysis; and, c) an integral sensor for effecting an analysis and providing a result relating to an analyte present in a foetal blood sample taken from a foetus when the foetal probe is in use.

Preferably, the disposable sensing probe comprises integral heating means for maintaining the temperature of the secured blood sample at a desired level.

The present invention also conveniently provides a kit of parts for a foetal probe, the kit of parts comprising: a) a reusable monitor; and, b) a disposable sensing probe..

There now follows by way of example of the invention a detailed description which is to be read with reference to the accompanying drawings in which: Figure 1 shows a block diagram of the invention; Figure 2 shows a side elevation of the invention; Figure 3 shows a left hand end view of the invention shown in Figure 1; Figure 4 is a diagrammatic representation of the invention when in use.

The foetal probe 2 of the present invention facilitates blood samples to be obtained in situ and at smaller cervical dilatations. Use of the foetal probe 2 is much less uncomfortable for the mother as it avoids the need to insert a large speculum into the vagina. In addition, any delays in obtaining the pH assessment are minimal resulting in a significant improvement in foetal care and a proportionate reduction in unnecessary Caesarean sections. This would also result in significant financial savings.

The foetal probe 2 is hand held and capable of producing a rapid pH reading.

The foetal probe 2 is essentially in two parts, a reusable monitor 4 containing the electronics, controls and display, and a disposable sensing probe 6 comprising of a lancet 8 and pH sensor 10, see Figures 1 and 4.

As can be seen from Figure 1, the reusable monitor 4 forms the main interface to the user and as such incorporates a general user interface, necessary hardware, operating software, power management and regulation with an optional communications interface.

The disposable sensing probe 6 allows access to the foetus and incorporates the integral lancet 8, the necessary sensing elements, fluidics, fluidics controls, and heating element.

The integral lancet 8 is capable of coming into contact with the foetal scalp FS where activation results in a scalp incision, which produces a foetal blood sample for analysis The integral fluidics functions to transport the blood sample to the sensing elements.

The pH sensor 10 is capable of providing a result relating to the analyte present.

The disposable sensing probe 6 includes an integral heating element 12, which is capable of maintaining the temperature of the foetal blood sample at the desired level.

The disposable sensing probe 6 further comprises fluidics control capable of transporting the blood sample to the sensing elements as well as calibration and flush solutions.

In order to maintain the accuracy and quality assurance of the foetal probe 2, a calibration and a quality control system is also incorporated therein.

The foetal probe 2 differs from existing prior art as the entire unit can be held in one hand throughout the duration of the procedure from insertion, extraction of blood sample, and reading all combining to produce a result more quickly. An image of the assembled foetal probe 2 can be seen in Figure 2.

The reusable monitor 4 can be used for multiple patients. As can be seen in Figure 3 it comprises of a Lancet Release Button 20 to active the lancet 8 thereby piercing a foetal scalp. a Display Unit 22 for displaying the result obtained from analysis of foetal blood sample, instrument status, errors and prompts, and a series of operational buttons 24, 25, 26 and 27 for power, calibration and quality control.

During operation, the foetal blood probe 2 will be held predominately by the index and middle fingers on the underside and with the lancet release button 20 operated by the thumb in a similar fashion as to the operation of a syringe when injecting.

The display shown in Figure 3 represents that for a right hand user where the buttons 24 to 27 are placed on the left side to minimise the risk of pressing in error.

Similar units with buttons on the right can be provided for left handed operators.

The disposable sensing probe 6 is a pre-packed sterile unit, up to 15mm in diameter and in variable lengths of up to 15cm to ensure adequate access depending on foetal station.

The disposable sensing probe 6 is designed and intended for use on a single patient for single, or multiple samples then disposed of in clinical waste.

Made of standard materials, the disposable sensing probe 6 contains a minimal number of components to minimise consumable cost.

The disposable sensing probe 6 is attached to the reusable monitor 4 in such a way that a coupling 30 of the disposable sensing probe 6 to the monitor 4 can only be undertaken once, thereby preventing reattachment and reuse and minimising the risk of cross contamination between patients and samples Prevention of reuse of the disposable sensing probe 6 may be ensured electronically.

Electronic options include the incorporation of a fuse or weak link in the electronic circuitry, which is blown on first use, or a memory element where upon first use a code is stored in memory element by electronics and software, which indicates to the system that the disposable sensing probe 6 has been used.

On first initialisation the memory element is interrogated to identify the disposable sensing probe 6 integrity state. Location dowels will be used to ensure the disposable sensing probe is colTectly attached and secured by a threaded coupling, not shown.

The foetal probe 2 works by attaching the disposable sensing probe 6 to the monitor 4.

The foetal probe 2 is then inserted disposable end 2a first into the vagina such that a seal 32 is formed against the scalp FS of the foetus, see Figure 4. A plunger activated on the monitor 4 releases the lancet 8, which pierces the scalp FS of the foetus.

Blood is drawn up into a sensor chamber 34 by a vacuum, which is formed as the lancet 8 releases. Foetal blood will then be in contact with the sensor 10 and a pH reading is displayed on an LCD screen 22 such that the user can observe the reading.

Calibration solutions will be provided with each disposable unit such that accuracy of measurements can be assured. Similarly, a flush solution will also be provided to enable the sensor to be cleansed between readings. Current practice involves wiping the scalp with sterile wipe prior to sampling though an option for an integral flush solution in the disposable sensing probe 6 can be added.

The following properties are present on the basic foetal probe 2 described above: * ISFET pH sensor, Optical pH sensor, or Glass pH electrode; * rigid disposable unit; integrated reference sensor; * error display; * device self check prior to use; * mechanical lancet activation and release; * battery powered -rechargeable; * stand to charge monitor unit when not in use; and, * integral heating element maintains sample temperature at desired level; Further option to enhance the basic device can be added, these include the following: * addition of more analytes; * flexible disposable unit; * semi rigid disposable unit; * option for pole mounted monitor to connect to device; * connection via cable to separate electronic monitor unit; * connection wirelessly to separate electronic monitor unit; * external reference sensor on disposable; * ability to connect to ECG monitor; * ability to connect to hospital information systems; * ability to connect to other monitor systems; * disposable unit powered by monitor unit; * disposable unit with integrated power supply in case of wireless option; * lancet operated electronically; * lancet operated mechanically; * lancet operated electromechanically; * error log; * connectable to printer; * pre-calibrated disposable; * disposable containing flush solution; * disposable containing calibration solution; * disposable containing calibration and flush solutions * connectable to printer * memory store of patient II) and readings; * integrated flush pump; * reduction in foetal risk and, * reduces patient and foetal discomfort.

Claims

CLAIMS1. A foetal probe comprising means for securing a foetal blood sample, characterised in that the foetal probe is a two-part assembly comprising a reusable monitor and a disposable sensing probe.
2. A foetal probe according to Claim 1, characterised in that the disposable sensing probe comprises: a) a lancet capable of coming into contact with a foetal scalp when the foetal probe is in use in order to secure a foetal blood sample; b) integral fluidics for transporting the foetal blood sample for analysis; and, c) an integral sensor assembly for effecting an analysis and providing a result relating to the analytes present in a foetal blood sample taken from a foetus when the foetal probe is in use.
3. A foetal probe according to Claim 2, characterised in that the disposable sensing probe comprises integral heating means for maintaining the temperature of the secured foetal blood sample at a desired level.
4. A foetal probe according to either one of Claims 2 and 3, characterised in that the disposable sensing probe also comprises calibration and quality control means for maintaining the accuracy of the analytical results obtained from the analyte when the foetal probe is in use.
5. A foetal probe according to any one of Claims 1 to 4, characterised in that the reusable monitor comprises: a) lancet control means for operation of the lancet when the foetal probe is in use; and, b) a digital display for showing the resulting analysis of the analyte present in the foetal blood sample taken from a foetus when the foetal probe is in use.
6. A foetal probe according to any one of Claims 1 to 5, characterised in that the reusable monitor comprises functional controls for use when the foetal probe is in use for calibration and quality control of the foetal blood sample.
7. A foetal probe according to any one of the preceding Claims, characterised in that the foetal probe comprises quick release means for connecting the reusable monitor and the disposable sensing probe so that, when used, a disposable sensing probe may be disconnected and replaced by an unused disposable sensing probe.
8. A foetal probe according to any one of Claims 2 to 7, characterised in that the disposable sensing probe comprises means for delivering a flushing solution to facilitate cleansing of the disposable sensing probe between successive samples of foetal bloods.
9. A foetal probe according to any one of the preceding Claims, characterised in that the reusable monitor comprises a power pack in the form of a rechargeable battery.
10. A foetal probe according to any one of the preceding Claims, characterised in that the foetal probe comprises communication means for wirelessly downloading information secured in relation to a foetal blood sample to peripheral monitors, hospital information systems, printers and a memory store relating to the foetus from whom a blood sample id secured.
11. A foetal probe according to any one of the preceding Claims, characterised in that the foetal probe can be operated electrically, mechanically or electromechanically.
12. A foetal probe according to any one of the preceding Claims, characterised in that the foetal probe may be used to determine, inter alia, the pH of the foetal blood sample.
13. A foetal probe according to any one of the preceding Claims, characterised in that the foetal probe may be used to determine analytes such as: p02, pCO2, Na, Ca, Cl and K of a foetal blood sample.
14. A method of securing a foetal blood sample using a foetal probe according to any one of the preceding Claims, the method comprises the steps of: a) connecting a disposable sensing probe to a reusable monitor; b) inserting the disposable sensing probe end first into the vagina such that a positive seal is formed against the scalp of the foetus; and, c) activating a plunger of the reusable monitor to release a lancet of the disposable sensing probe whereby the scalp of the foetus is pierced and a blood sample is secured for analysis of the analytes as required.
15. A reusable monitor for use with a foetal probe, the monitor comprising lancet control means for operation of a lancet, when the reusable monitor is in use and connected to a disposable sensing probe, the reusable monitor also comprising a display for showing the resulting analysis of an analyte present in foetal blood sample taken from a foetus when the foetal probe is in use and connected to a disposable sensing probe as aforesaid.
16. A reusable monitor according to Claim 15, characterised in that the monitor also comprises functional controls whereby, when the foetal probe is in use, for calibration and quality control of the foetal blood sample.
17. A reusable monitor according to either one of Claims 16 and 17, characterised in that the reusable monitor comprises a quick release means for connection to a disposable sensing probe so that, when used, a disposable sensing probe may be disconnected and replaced by an unused disposable sensing probe.
18. A reusable monitor according to any one of Claims 15 to 17, characterised in that the reusable monitor comprises a power pack in the form of a rechargeable battery, the reusable monitor further comprising communication means for wirelessly downloading information secured in relation to a foetal blood sample to peripheral monitors, hospital information systems, printers and a memory store relating to tha foetus from which a blood sample is secured.
19. A disposable sensing probe for use with a foetal probe, characterised in that the disposable foetal probe comprises: a) a lancet capable of coming into contact with a foetal scalp when the foetal scalp is in use in order to secure a foetal blood samples; b) integral fluidics for transporting the foetal blood sample for analysis; and, c) an integral sensor for effecting an analysis and providing a result relating to an analyte present in a foetal blood sample taken from a foetus when the foetal probe is in use.
20. A disposable sensing probe according to Claim 19, characterised in that the disposable sensing probe comprises integral heating means for maintaining the temperature of the secured blood sample at a desired level.
21. A kit of parts for a foetal probe, the kit of parts comprising: a) a reusable monitor according to any one of Claims 15 to 18; and, b) a disposable sensing probe according to either one of Claims 19 and 20.
22. A foetal probe substantially as hereinbefore described with reference to the accompanying drawings.
23. A reusable monitor substantially as hereinbefore described with reference to the accompanying drawings.
24. A disposable sensing probe substantially as hereinbefore described with reference to the accompanying drawings
25. A kit of parts substantially as hereinbefore described with reference to the accompanying drawings.