SOME EFFECTS OF RAISED INTRAPULMONARY PRESSURE IN MAN
ROYAL AIR FORCE FARNBOROUGH (UNITED KINGDOM) INST OF AVIATION MEDICINE
Pagination or Media Count:
Positive pressure breathing with oxygen is a means whereby an acceptable arterial oxygen tension may be maintained at altitudes in excess of 40 000 ft. The nature of the disturbances induced by raising the intrapulmonary pressure by between 30 and 140 mmHg has been investigated. It has been shown that these disturbances may be reduced to within acceptable limits by applying counterpressure to certain specific regions of the body. Pressure breathing at these pressures distends the lungs and induces a marked alveloar hyperventilation. The application of counterpressure to the trunk reduces these effects and is essential at positive pressures greater than 40 mmHg. The use of an oronasal mask for pressure breathing allows distension of the mouth and pharynx, increased activity of the carotid baroreceptors and haemorrhages in the conjunctivae and tympanic membrane. Counterpressure to the head and neck is required at positive pressures above 65 mmHg.
- Stress Physiology