Abstract
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 (≡ 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 PO2 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.
Résumé
Objectif
Présenter l’utilisation passée et présente de la respiration sous pression, non par des patients, mais par des pilotes de chasse.
Source
La plupart des références historiques et récentes proviennent de journaux de médecine aéronautique qui ne sont pas facilement accessibles aux anesthésiologistes.
Constatations principales
La respiration sous pression à des niveaux modérés de pression des voies aériennes a été un avantage tactique en altitude pour les pilotes de chasse de la Seconde Guerre mondiale. Avec les chasseurs à réaction rapides et très maniables d’aujourd’hui, des pressions des voies aériennes beaucoup plus élevées, de l’ordre de 8,0 kPa (≡,60 mmHg), sont utilisées en conjonction avec un gilet thoracique à contre-pression et un vêtement anti-G pour l’abdomen et les membres inférieurs. La pressurisation est activée automatiquement en réponse à des accélérations +Gz et à une perte potentiellement catastrophique de la pressurisation de la cabine en altitude. Pendant les accélérations +Gz, la respiration sous pression maintient la perfusion cérébrale en élevant la pression artérielle générale, ce qui augmente le niveau de tolérance G qui est fournie seulement par l’usage de vêtement anti-G et les angles du siège inclinable. Le pilote n’a plus à réaliser des manœuvres difficiles et rigoureuses qui pourraient monopoliser son attention. Avec la perte de pressurisation de la cabine en altitude, la respiration sous pression d’oxygène à 100 % selon des pressions des voies aériennes élevées permet de maintenir la PO2 alvéolaire du pilote à un niveau de sécurité pendant la descente d’urgence.
Conclusion
Introduite dans l’aviation militaire, la respiration sous pression pour la tolérance G et pour l’altitude est présentée de façon élémentaire. Le sujet peut attirer de nombreux anesthésiologistes intéressés à la physiologie générale.
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Lauritzsen, L.P., Pfitzner, J. Pressure breathing in fighter aircraft for G accelerations and loss of cabin pressurization at altitude — a brief review. Can J Anesth 50, 415–419 (2003). https://doi.org/10.1007/BF03021042
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DOI: https://doi.org/10.1007/BF03021042