Oxygen masks

Details Oxygen masks Oxygen masks

1995-01-26

1996-07-23

Burr, Edgar S.

Surgery

Respiratory method or device

Face mask covering a breathing passage

12820123, 12820211, 12820525, 2 214, 600 20, A62B 1802

Patent

active

055380018

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

The present invention relates to pressure breathing masks such as oxygen masks used by military aircrew.


DISCUSSION OF PRIOR ART

It is well known that human life relies on the absorption of oxygen by the lungs. For absorption to take place the partial pressure of oxygen in the lungs must be above a certain minimum pressure.
It is also well known that one effect of increasing altitude is a reduction in air density (and hence in air pressure). To compensate for this effect aircrew are provided, through specially designed masks, known as oxygen masks, with an air supply having an enhanced, eventually pure, oxygen content. However an altitude, normally about 37,000 feet, is eventually reached where the pressure of even pure oxygen is insufficient for it to be absorbed. To overcome this problem aircraft cabins are pressurised.
The effect of loss of pressure in the cabin of an aircraft flying above the critical altitude is that occupants of the cabin rapidly become hypoxic (from lack of oxygen) and the consequent loss of consciousness can occur very quickly. To cope with this eventuality, systems have been developed whereby loss of cabin pressure results in the supply to oxygen masks of pure oxygen at increased pressure relative to ambient pressure, sufficient for it to be absorbed by the lungs in an amount sufficient to prevent hypoxia. For this pressurised breathing to be effective, an oxygen mask must clearly form a gas tight seal with its wearer's face. Masks held in position sufficiently tightly to fulfil this condition would be unbearably uncomfortable at this tightness, so masks have been developed which can be tightened when the wearer notices the onset of pressure breathing. Currently used masks each have a rigid exoskeleton, normally of a Fibre (usually glass fibre) Reinforced Plastic Material, to which is attached a flexible face piece. It is, of course, essential that the face-piece be flexible to allow it to remain in sealing contact with a wearer's face despite the inevitable changes in contour of the face (due, for example, to the effects of talking and to the effects of gravitational forces during manoeuvring of the aircraft). The exoskeleton is attached to a helmet by a mechanism which can be tightened to bring the facepiece into tighter contact with a wearer's face. The conventional arrangement includes a toggle bar which the wearer moves physically with his fingers.
Over recent years, pressure breathing has been introduced to help counter the effects of acceleration, in addition to the traditional role as a protection against hypoxia at high altitude. Thus, modern high speed aircraft, particularly military fighter aircraft, have reached a state of development where the gravitational forces imposed on their crew can reach levels where, were pressure breathing to be introduced whilst manoeuvring, the physical task of tightening the oxygen masks would be difficult or even impossible. There are known oxygen masks designed to tighten automatically when pressure breathing is applied, but these are complicated and expensive, relying on a bladder system, positioned at the rear of the helmet, which upon inflation re-orientates the helmet position and alters the whole geometry of the whole helmet/mask system. Such a system is described in UK Patent GB-B-826,198. However with this system a comparatively large bulk (helmet and mask) has to be moved. There can also be a detrimental effect upon any helmet mounted device such as, for example, a weapons sight or visual display.
In a more robust system, as described in Application PCT/GB91/01034 (published as WO 92/00120) an inflatable bladder is positioned between the rigid exoskeleton and the flexible face piece.


SUMMARY OF THE INVENTION

According to the present invention a pressure breathing mask includes a rigid exoskeleton, means for attaching the exoskeleton to a helmet, a flexible facepiece with a gas delivery connection, inflatable means positioned between the exoskeleton and the facepiece, and means for automatically

REFERENCES:
patent: 2827900 (1958-03-01), Marietta
patent: 3513841 (1970-05-01), Seeler
patent: 3910269 (1975-10-01), Ansite et al.

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