Ventilatory response to forward acceleration

¹ Acceleration Section, Biophysics Branch, Aerospace Medical Laboratory, Wright-Patterson Air Force Base, Ohio

Two series of experiments dealing with the effect of forward acceleration on respiration in man were performed. In both series of studies the trunk was inclined 12 degrees in the direction of acceleration and a rate of onset of 1 g/sec. was used. In the first series, the effect of 5, 8 and 12 g on respiratory frequency, tidal volume, minute volume and nitrogen elimination was determined. Frequency increased, reaching an average of 39.2 cpm and tidal volumes decreased to an average of 318 cc at 12 g. The volume of nitrogen eliminated during a 30-second period, breathing O₂ at 12 g, was essentially unchanged, suggesting that alveolar ventilation did not decrease. In the second series, O₂ consumptions were measured before, during and after accelerations of 5, 8, 10, and 12 g. O₂ consumptions increased with acceleration and it is presumed that the extra work of breathing may be an important contributing factor.