The Journal of Thoracic and Cardiovascular Surgery, Vol 71, 268-273, Copyright © 1976 by The American Association for Thoracic Surgery and The Western Thoracic Surgical Association
The effects of carbon dioxide on pulmonary mechanics in hyperventilating, normal volunteers
M Hilberman, JS Hogan and RM Peters
Transpulmonary pressure, air flow, and end-tidal carbon dioxide levels were
measured in normal human volunteers during hypocapnic, eucapnic, and
hypercapnic hyperventilation. Respiratory rate and tidal volumes were well
matched at a minute ventilation of 52 L. on three inspired gas mixtures: 21
per cent oxygen and 79 per cent nitrogen; 5 per cent carbon dioxide, 21 per
cent oxygen and 74 per cent nitrogen; and 12 per cent carbon dioxide, 21
per cent oxygen and 67 per cent nitrogen. Respiratory rate, tidal volume,
lung compliance, resistance, and resistive work per liter were calculated
with a digital computer. In 13 experiments in 7 normal volunteers, no net
bronchoconstriction or bronchodilatation was observed when eucapnic
hyperventilation was compared to hypocapnic or hypercapnic
hyperventilation. During hyperventilation of this degree, a change in
bronchomotor tone owing to alteration in arterial or alveolar PCO2 either
does not occur or else is masked by other reflexes or mechanical factors
acting on the bronchi.
