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EFFECT OF POSITIVE PRESSURE BREATHING ON THE RESPIRATORY MECHANICS AND TOLERANCE TO FORWARD ACCELERATION
AEROSPACE MEDICAL RESEARCH LABS WRIGHT-PATTERSON AFB OHIO
Pagination or Media Count:
The main factors limiting tolerance to forward acceleration are dyspnea, chest pain, and difficulty in inspiring. Previous studies of the mechanics of respiration during forward acceleration revealed the following 1 lung volumes decreased proportionately with the exception of residual volume 2 resting midpulmonary position decreased 3 intrapulmonic pressure increased for a constant volume 4 static and dynamic pulmonary compliance decreased 5 elastic work of breathing increased due to the work necessary to overcome the additional resistance resulting from acceleration. The effects of positive pressure breathing on lung volumes and time tolerance to forward acceleration of 12 trained subjects were studied. Positive pressure breathing significantly increased lung volumes, particulary the expiratory reserve volume. This increase in lung volumes was associated with a 67 percent mean increase in time tolerance. Positive pressure breathing is therefore both a practical and physiologically sound countermeasure by which tolerance to forward acceleration can be improved and human safety during prolonged exposures increased. Author
APPROVED FOR PUBLIC RELEASE