Impairment of oxygen transfer in the lung by increasing oxygen concentration during halothane and trichloroethylene anaesthesia.

Two groups of 10 patients were studied during artificial ventilation with a mixture of oxygen, nitrogen and either halothane or trichloroethylene. Arterial blood and respiratory gas smapling was performed at FIO2 values of 0.33, 0.5 and 0.75. The efficiency of oxygen transfer, expressed as the difference between pulmonary end-capillary and arterial oxygen content, was found to decrease progressively in most patients as the alveolar partial pressure of oxygen increased. This pattern of response may be explained by the effect of oxygen on regulatory reflexes in the lung.