SOME EFFECTS OF RESTRICTION OF CHEST CAGE EXPANSION ON PULMONARY FUNCTION IN MAN: AN EXPERIMENTAL STUDY*†

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Abstract
The total lung capacity and its subdivisions were reduced by restricting chest expansion in normal man. The lung pressure-volume relationship was altered (smaller volume resulting from unit pressure) over much of the vital capacity. Respiratory frequency was increased and tidal volume was reduced. Airway conductance at resting lung volume was not changed despite reduced functional residual capacity. There was slightunevenness of alveolar ventilation with evidence of non-orpoorly ventilated lung units. Systemic arterial O2 tension fell during O2 breathing, and there was a slight increase of peripheral venous pressure. Following release of chest restriction, the mechanical changes in the lungs were reversed via a hysteresis-like pathway. They appear to be explained in part by the opening of lung units which had become closed during chest restriction.