WO2003000328A1

WO2003000328A1 - Face mask

Info

Publication number: WO2003000328A1
Application number: PCT/GB2002/002918
Authority: WO
Inventors: Desmond Bryan Mills; Kevin Herbert
Original assignee: Brown, Stephen, Colin; Mills, Malcolm, Bradley
Priority date: 2001-06-25
Filing date: 2002-06-25
Publication date: 2003-01-03
Also published as: GB0115567D0; GB2379612A

Abstract

A face mask, generally shown in (1) in figure (1) comprising a mask part (1a) for placing over at least the mouth of a patient with part (2a) forming a seating which comes into contact with the patient. The face mask has an inlet (2) through which air passes into the mask for delivery to the patient. Gases exhaled by the patient pass through a first outlet (3) leading to an indicator (8), which can measure parameters such as the pH of the expelled air and provide a guide to the patient's condition. The air having passed over or through the indicator is expelled from the face mask via second outlet (5). The airflow into and out of the mask is controlled by flow-control valve (4).

Description

FACE MASK

This invention relates to a face mask adapted for use in cardiopulmonary resuscitation (CPR) , or for mouth to mouth resuscitation.

Face masks are known that have a face engaging part which surrounds at least the mouth of the patient so that substances such as oxygen and gaseous medication can be administered effectively to the patient. Known face masks are shown in US 4811730 which illustrates a CPR facemask, as does US 5469842. US 5735265 discloses a CPR face mask with a filter to provide protection from patient-expired condensate. US 4834085 illustrates a person-to-person resuscitation device, while US 4337767 and US 3815596 discuss a disposable anesthesia mask cover and a disposable face mask respectively. US 3905361 discloses an apparatus for sealing the oesophagus whilst providing artificial respiration and evacuating the stomach. Also known are face masks comprised of shields which can be used for mouth to mouth resuscitation. US4050457 and US 3626936 describe typical shields which are constructed of a one piece flexible material that is capable of assuming a complementary sealing relationship over a patient's face. The shields are of dimensions sufficient to cover the face from ear-to ear and from the bridge of the nose to the bottom of the chin. Other mouth to mouth resuscitation masks are described in US 5511543, which discloses a resuscitation device having a unidirectional valve. Disposable resuscitation devices are also described in US 3957046 and US 3802428. Known face masks often include an inlet through which a gas is blown onto a patient via a first outlet. Air exhaled by a patient is vented from the face mask by a second outlet. The flow or air between the first and second outlets is controlled by a flow-valve.

In the prior art, although there is control of the gas or air that is being administered to the patient, there is no ready indication of how the gas or air is affecting the patient's status/metabolism. The European Resuscitation council states the following: "The ^λgold standard' sign of cardiac arrest is an absent carotid (or other large artery) pulse. It has been shown, however, that assessment of the carotid pulse is time consuming and leads to an incorrect conclusion (present or absent) in up to 50% of cases. For this reason, training in detection of the carotid pulse as a sign of cardiac arrest is no longer recommended for non-healthcare persons. "

An aim of the present invention is to provide a device that provides a rapid and easily readable indication of a patient's condition. Ideally such a device would indicate the patient's condition passively in order to avoid further analytical time delays. Preferably, the device would be small, portable, light and be part of or used in combination with an existing emergency medical device. Furthermore the device ideally has the advantage of being relatively inexpensive to produce and simple to maintain which would enable widespread public use.

The invention provides a face mask having a first face-engaging portion which fits over at least the mouth of a patient, an inlet for delivery of a substance to a patient, and an outlet for receiving gases expelled from the patient, the inlet and outlet being separable by a flow-control valve, characterised in that the face mask includes a tester associated with the outlet that indicates the components of gases being exhaled by the patient. Preferably the tester is a substrate which gives a visual indication of the gaseous components. The tester ideally would be a pH-sensitive paper or, for example, powder particles or compound granules which are reactive. The tester would react with the exhaled gases in the patient's breath to provide a colour indication of the gases that are being released by the patient.

It is desirable that the carbon dioxide level in the breath of a patient is measured during CPR, although a reverse test could be carried out by which the levels of oxygen or even nitrogen that are being exhaled could be measured. It is envisaged that, as well as oxygen levels, other components can be measured such as ketones, for example, if a person has kidney failure, or poisons, e.g. carbon monoxide. It is also envisaged that alcohol levels can be measured by using this face mask and this would be useful as an indication of whether it was safe to give medication to a patient that was found in an unconscious state.

Ideally, the face mask is adapted for use in CPR resuscitation or mouth to mouth resuscitation. However, it is envisaged that the mask can be used in other situations, for example as a mask used in anaesthesia or for the delivery of medicaments to a patient, where it is advantageous to monitor the patient's response to medicaments that are being administered. The medicaments may be either gaseous medicaments or alternatively, they may be administered by other means, for example intravenously.

It is desirable that the tester is monitored by a detector that can analyse the result produced. Thus the detector may incorporate a processor that analyses the results against data setting out acceptable limits or standards for the components in the breath that is measured. If the results do not fall within parameters set by the data, then a warning may be given, which could be an audible or visual warning, to the person who is assisting the patient.

Embodiments of the invention will now be described by way of example only, with reference to the accompanying drawings in which: Figure 1: Shows a perspective view of a face mask in use;

Figure 2a: Shows a sectional view of a face mask of the prior;

Figure 2b: Shows a sectional view of a face mask as shown in figure 1; Figure 3: Shows a graph illustrating carbon dioxide changes during CPR; and

Fig 4 : Shows a perspective view of another form of face mask which is used in mouth to mouth resuscitation.

As shown in Figure 1, the face mask, which is generally shown as 1, comprises a mask part la, which is placed over at least the mouth of the patient, though it may extend over the nose and, possibly, the mask could be a full facial mask. Such an arrangement would be more desirable for the treatment of babies in order to obtain an adequate seal around the baby's face.

Gas or air is delivered to the face engaging part of the mask by an inlet 2, through which air can be blown into the mask by a person giving CPR to a person undergoing VT . The air passes through a first outlet, generally indicated as 2a, into a patient's mouth. Air to and from the patient is controlled by control valve, shown as 4. Figures 2a and 2b each show a sectional view of face masks which clearly show the arrangement of inlet 2, a first outlet 3 from the mask, second outlet 5 and control valve 4. Figure 2a shows a face mask with a simple paper indicator, while figure 2b shows an indicator including an electronic display

A flow control valve 4 is positioned between the inlet 2 and the first outlet 3 and a second outlet 5. The flow control valve 4, which ideally is a one way valve, directs air passing upwardly from the patient's mouth into the first outlet 3 so that the air is caused to be released to the external atmosphere through the second outlet 5, without passing to the inlet 2. The flow control valve has a flexible diaphragm 6, operable to prevent airflow from the inlet 2 to the second outlet 5 when the CPR-giving person is blowing into the inlet and to prevent air flow from the first outlet 3 to the inlet 2 when air passes upwardly from the patient's mouth into the first outlet 3.

A filter 7 is located immediately upstream of the diaphragm with respect to airflow blown into the first inlet by the CPR-giving person. The diaphragm has a filter- blocking position assumed during patient exhalation to protect the filter from patient-expired air on the mask. As shown in Figure 2a, the gas indicator 8, comprises a pH- sensitive indicator, utilising disposable colorimetric paper, placed in an outlet path leading to the second outlet 5. Preferably, the indicator is a sensitive paper inside a transparent air tube. This is a specially treated membrane sensitive to changes in pH that results from exposure to C0₂. As the percentage of C0₂ in the patient- exhaled air rises, the colour of the detector changes from purple (less than 0.5%) to tan to yellow (4 to 5%). The presence of a tan or yellow colour is an indicator of a return of spontaneous circulation in the CPR patient. As shown in Figure 2b the proportion of gas in exhaled air can be shown by using an electronics display. The indicator 8, includes a power supply for the display and for the monitoring equipment. This may be easily disassembled for ease of replacement of component parts which will contribute to the prolonging of the life of the equipment that is used. Alternatively, the indicator 8 may be a disposable part which can be replaced when the power source is depeleted.

End-tidal C0₂ monitoring has recently been promoted to have, among other uses, the ability to detect the return of spontaneous circulation. The percentage of carbon dioxide contained in the last few millilitres of the patient's exhaled air is called the end-tidal carbon dioxide (because its exhaled at the end of the tidal volume) . As can be seen from Figure 3, air exhaled by normally-perfused patient should contain about 4% to 5% C0₂. Patients in cardiac arrest are not well perfused at all. Even during the best CPR, tissue perfusion is very low and, as a consequence, end-tidal C0₂ falls only to 25 to 30% of normal. When CPR is successful, a sudden increase in end-tidal C0₂ may be the first indication of a return of spontaneous circulation, as large quantities of "stale" C0₂-rich blood are returned to the lungs. A simple CPR respirator containing a tester/sensor could be used to indicate return of spontaneous circulation.

As the percentage of C0₂ in the patient exhaled air rises, the colour of the detector changes from purple (less than 0.5%) to tan to yellow (4 to 5%).

Presence of a tan or yellow colour is an indicator of a return of spontaneous circulation in the CPR patient and the rescuer should then attempt a pulse check to verify the status of the patient.

It is envisaged that the outlet valve could be coated in, for example, a pH sensitive chemical to allow for easier visual identification of possible circulation. It is possible that other colour change indicators could be used, depending on the type of tests to be carried out, which will depend on the substances that are to be tested for.

Also, the face-mask can be connected to an oxygen cylinder via the inlet valve to allow deliveries of 40-100% pure oxygen as is commonly used in post-CPR treatment. Furthermore, it is envisaged that the tester could be a photoelectric sensor sensitive to C0₂ concentrations from IR absorption. This would provide an electronic face mask. Crossing of a C0₂ threshold (which is preferably 3%) would lead to an audible or visual alarm indicating a potential return of spontaneous circulation. The electrical sensor could also contain a low battery warning alarm (again visual or audible) to pre-warn the user adequately of potential failure.

The electronic face mask could contain sensors capable of monitoring airflow and an indicator/alarm of this. A lack of patient-exhaled airflow would be an indication of an airway blockage that could become potentially fatal if not removed. Also, by monitoring airflow and being attached to an oxygen cylinder, the mask could automatically shut off the inlet/outlet valves to allow for demand feeding of oxygen. Thus the patient would receive oxygen when he or she breathed in but would not have to fight against this oxygen flow when he or she breathed out.

When using an electronic facemask, a C0₂ photoelectric sensor would allow approximation of the patients 0₂/C0₂ level, allowing for measurement of the amount of oxygen saturation in the patients blood and thus being able to indicate whether further oxygen treatment is necessary. Also the electronic facemask could be connected to an AED allowing the device to monitor return of spontaneous circulation, airflow, oxygenation levels etc. and adjust or act accordingly.

As well as being used for CPR, the face mask as described, with minor adaptations, could be used in mouth- to-mouth resuscitation. A face mask for mouth-to-mouth resuscitation, would be particularly useful for members of the public to use.

As shown in Figure 4, a face mask adapted for mouth to mouth resuscitation comprises a shield 9, which includes a mouth opening 10, located substantially centrally thereof. The mouth opening includes a dual valve device 11 or airflow control device adapted to fit within and/or over a patient's mouth to permit air to be blown through the opening into the patient's mouth and to permit separately the exhalation from the patients lungs to be released through the second outlet of the dual valve. On forced inhalation the exhalation valve is closed and on patient exhalation the inhalation valve is closed preventing a reverse flow of fluids and air from the patient to the user .

The outlet valve contains a carbon dioxide sensor 12 which is capable of indicating any dramatic change in carbon dioxide levels as is commonly associated with a return of spontaneous circulation following a pulseless period.

For ease of use, preferably the inlet valve comprises of a flexible tube 13 with corrugations 14 to allow flexibility. This allows the user to perform mouth-to-mouth resuscitation from the side of the patient. As a further embodiment the mouthpiece is moulded such that resuscitation from the side becomes the obvious and easiest method of use. As far as possible the device is constructed substantially of flat and flexible materials to allow folding and packaging of the device in a compact condition and can be adapted to be discarded after a single use. The mouth to mouth device includes a spring mounted blocker 14, which preferably includes a filter material. This blocker is in proximity to a bypass duct 15. As the rescuer blows air down the tube 13 into the patient, the blocker is pushed down the tube to the patient and air passes through the bypass duct 15 to the patient. When the patient exhales, the blocker is pushed back towards the rescuer end of the tube 13 and blocks the bypass duct so that air is forced towards the indicator 12.

It is to be understood that the above detailed description cover embodiments of the invention that are provided by way of example only. Various details of design and construction may be modified without departing from the true spirit and scope of the invention as described.

Claims

1. A face mask having a face-engaging portion that is adapted to be placed over at least the mouth of a patient, an inlet for delivery of a substance to a patient, and an outlet for receiving gases exhaled by the patient, the inlet and outlet being separable by a flow-control valve, wherein the face mask includes a tester associated with the outlet, said tester being arranged to give an indication of the character and/or components of a gas or gases being exhaled by the patient.

2. A face mask according to Claim 1, wherein the outlet comprises first and second outlet portions the first outlet being arranged to direct gases exhaled from the patient to the tester, and the second outlet being arranged to vent gases that have passed through the tester from the face mask.

3. A face mask according to Claim 1 or Claim 2, wherein the flow-control valve is a one way valve.

4. A face mask according to Claim 3, wherein the flow-control valve is positioned prior to the first outlet portion.

5. A face mask according to Claim 4, wherein the flow-control valve includes a flexible diaphragm.

6. A face mask according to Claim 5, wherein pressure on the flexible diaphragm from a substance entering the face mask, causes the diaphragm to move so as to substantially prevent said substance from passing through the first outlet portion thereby contaminating the tester.

7. A face mask according to any preceding claim, wherein a filter is located upstream of the flow control valve to prevent particulates from reaching the patient.

8. A face mask according to Claim 7, wherein tester comprises a C0₂ detector for measuring carbon dioxide levels in the breath of the patient.

9. A face mask according Claim 8, wherein the tester comprises a monitor adapted to measure or detect the level of ketones or alcohol in the breath of a patient wearing the face mask.

10. A face mask according to any preceding claim wherein the tester comprises a pH sensitive material and is adapted to give an indication of the pH of the gases being exhaled by a patient wearing the face mask.

11. A face mask according to any preceding claim, wherein the tester provides a visual indication of the characteristics of the gases being exhaled by the patient wearing the face mask.

12. A face mask according to any preceding claim wherein the tester comprises an electronic indicator to provide an electronic indication of the components of gases in the breath of a patient wearing the face mask.

13. A face mask according to any preceding claim including an alarm to warn that the characteristic of the gas being expelled are at or have failed to reach certain parameters .

14. A face mask according to any preceding claim adapted for use in CPR resuscitation.

15. A face mask according to any of Claims 1 to 13 adapted for mouth to mouth resuscitation.

16. A face mask according to Claim 15, wherein the flow control valve comprises a spring mounted member, moveable by the force of air being forced into the face mask by a person providing mouth to mouth resuscitation and by the force of gases being exhaled by the patient.

17. A face mask according to Claim 16, wherein, movement of the spring mounted member controls flow of gases from the patient to the tester.

18. A face mask according to any of Claims 1 to 15, wherein a filter is associated with the spring mounted member to assist in preventing particulates entering the face mask.

19. A face mask according to any of claims 1 to 15 wherein the mask is disposable.