Response to high pressure oxygen of conscious volunteers and patients.

A trial is described in which 19 fit volunteers and 49 patients with malignant tumors have breathed oxygen at a pressure of 3–4 atm abs for periods of from 21 to 67 min in a pressure chamber filled with oxygen. Subjects at complete rest will not safely tolerate 4 atm abs for frac12 hr but are unlikely to show signs of oxygen toxicity in a similar period at 3 atm abs. One patient convulsed during decompression after 46frac14 min at 3 atm pressure. A slow, even rate of pressurization did not prevent the occurrence of otitic barotrauma in nine of the volunteers. The patients had myringotomies performed. Temperature and pulse rate changes are described.