Odsek za avtomatiko, biokibernetiko in robotiko

Nitrogen narcosis attenuates shivering thermogenesis

Mekjavić I., Savić S., Eiken O., Nitrogen narcosis attenuates shivering thermogenesis, Journal of applied physiology, 1995, 78, 6, str. 2241-2244.

Povzetek (angleško)
Thermoregulatory responses of eight healthy subjects (six men and two women) were compared when they were head-out immersed in 15 degrees C water at both 1 and 6 ATA. Both trials were conducted in a hyperbaric chamber. During the immersions, esophageal temperature (T(es)) and skin temperature at two sites (chest and calf) were recorded at minute intervals. Oxygen uptake was determined at 5-min intervals with the Douglas bag method. The order of the two trials was alternated. The rate of T(es) cooling was greater during the 6-ATA trial Š2.1 +/- 0.5 degrees C/h (SE)Ć than during the 1-ATA trial (1.3 +/- 0.5 degrees C/h; P less th. 0.01). Despite the greater rate of core cooling, and presumably a greater thermal drive for shivering, the oxygen uptake response for a similar decrement in T(es) was lower during exposure to 6 than to 1 ATA (P less th. 0.05). Also, for similar displacement in T(es), the subjects perceived the immersions at 6 ATA to be less cold than those at 1 ATA (P less th. 0.05). It is concluded that the development of hypothermia in compressed-air divers may be due, in large part, to the attenuation of heat production and cold perception. Most likely, the observed effects on the autonomic responses and thermal perception are due to an inhibitory action of hyperbaric nitrogen on central neural structures involved in temperature regulation.