[Evaluation of the effect of excess intrapulmonary pressure on human respiratory function]

The parameters characterizing lung ventilation and electrical activity of expiratory muscles were investigated in six healthy young men exposed to the positive intrapulmonary pressure 20, 30 or 40 mm Hg. Gas mixtures with a varying oxygen content were used. The effect of two compensatory devices that applied different counterpressures to the body surface was evaluated. It was found that the parameter that can best characterize the respiratory function in the case of a positive intrapulmonary pressure is electrical activity of expiratory muscles. The hypoxic effect makes no important contribution to the change of respiratory parameters during short-term exposures to the positive intrapulmonary pressure 20, 30 or 40 mm Hg. The different methods of applying compensation do not influence changes in the above respiratory parameters.