Cardiopulmonary Responses to Pressure Breathing

Positive pressure breathing (PPB) is used to maintain the alveolar partial pressure of oxygen during altitude exposures in excess of 12,000 meters (36,000 feet). At altitudes up to 33,000 feet the alveolar gas tensions may be kept within the normal range by increasing the concentration of oxygen in...

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Bibliographic Details
Main Authors: Stolp, Bryant W, Arles, Stephen P, Dear, Guy L, Chimlak, James M, Gleaton, Charles H
Format: Report
Language:English
Subjects:
ACCELERATION
ALVEOLI
Anatomy and Physiology
ARTERIES
CARDIOVASCULAR SYSTEM
CIRCUITS
CYCLES
GASES
HEART
HIGH ACCELERATION
HIGH ALTITUDE
LOW ALTITUDE
LUNG
MIXTURES
OXYGEN
PARTIAL PRESSURE
PE63231F
PRESSURE BREATHING
RATES
RESPIRATION
RESPONSE
SATURATION
Stress Physiology
TENSION
WUAL28300117
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Summary:Positive pressure breathing (PPB) is used to maintain the alveolar partial pressure of oxygen during altitude exposures in excess of 12,000 meters (36,000 feet). At altitudes up to 33,000 feet the alveolar gas tensions may be kept within the normal range by increasing the concentration of oxygen in the inspired gas mixture. Above this altitude, however, alveolar oxygen tensions fall below normal levels despite breathing 100% oxygen (Sharp & Ernsting, 1988). Furthermore, during high-acceleration (high-G) maneuvers, even at lower altitudes, there is a tendency for microatelectasis formation and development of intrapulmonary right-to-left shunt, which may be accentuated during 100% oxygen breathing (Wagner, et al. 1977). Raising the pressure inside the breathing circuit throughout the breathing cycle (PPB) is well established as a method of maintaining alveolar oxygen tension at high altitudes (Gagge, et al. 1945) and under high G- forces. Burns and Baildin (1988) studied the rates of arterial desaturation during acceleration with positive pressure breathing at 50 mmHg and 70 mmHg. They found that the rate of oxygen desaturation was less with PPB than without PPB suggesting a possible improvement in VAIQ relationships, at least in lowV a/Q regions or shunt. This is equivalent to continuous positive airway pressure (CPAP) used clinically to augment arterial oxygenation in patients.