Pressure breathing in fighter aircraft for G accelerations and loss of cabin pressurization at altitude - a brief review: (La respiration sous pression dans les avions de chasse soumis a des accelerations G et a la perte de pressurisation de la cabin

摘要

PURPOSE: The purpose of this brief review is to outline the past and present use of pressure breathing, not by patients but by fighter pilots. SOURCE: Of the historical and recent references quoted, most are from aviation-medicine journals that are not often readily available to anesthesiologists. Principal findings: Pressure breathing at moderate levels of airway pressure gave World War II fighter pilots a tactical altitude advantage. With today's fast and highly maneuvrable jet fighters, very much higher airway pressures of the order of 8.0 kPa ( identical with 60 mmHg) are used. They are used in conjunction with a counterpressure thoracic vest and an anti-G suit for the abdomen and lower body. Pressurization is activated automatically in response to +Gz accelerations, and to a potentially catastrophic loss of cabin pressurization at altitude. During +Gz accelerations, pressure breathing has been shown to maintain cerebral perfusion by raising the systemic arterial pressure, so increasing the level of G-tolerance that is afforded by the use of anti-G suits and seat tilt-back angles alone. This leaves the pilot less reliant on rigorous, and potentially distracting, straining maneuvers. With loss of cabin pressurization at altitude, pressure breathing of 100% oxygen at high airway pressures enables the pilot's alveolar PO(2) to be maintained at a safe level during emergency descent. CONCLUSION: Introduced in military aviation, pressure breathing for G-tolerance and pressure breathing for altitude presented as concepts that may be of general physiological interest to many anesthesiologists.