Effect of Breathing O₂ at One Atmosphere on the Response to Cold in Human Subjects

¹ From the Laboratory of Biophysics, University of Western Ontario, London, Canada

Experiments were designed to verify the suggestion, from previous work, that breathing O₂ decreased the O₂ consumption of humans during exposure to cold. The results of 4 measurements on each of 10 subjects, dressed and at normal room temperature (25°C) showed no significant difference between breathing air and O₂ (P = 0.6). During the next experiments the room temperature was about 10°C. Two determinations of the O₂ consumption were made while the subject was covered with blankets and four more after the nude subject had been exposed to room temperature for 20 minutes. Movements of the suspended bed were recorded during shivering. An electromyograph record was also obtained. For analysis the results were grouped into successive pairs of observations for breathing air and O₂. The average decrease in O₂ consumption when breathing O₂ was 19.7 cc/min/m² which represented 30% of the mean increase in O₂ consumption in the cold and was significantly different from zero (P < 0.001). Breathing O₂ also resulted in a lower heart rate (3 beats/min., P < 0.001), lower minute volume (13.8% of increase due to cold, P = 0.02), lower respiratory frequency (0.48 cpm, P = 0.08) and lower EMG (16.8 µv, P = 0.08). Tremor was not affected by O₂ (P = 0.90).