Regional skin temperatures associated with total sympathetic blockade in conscious dogs

Abstract

Multiple regional skin temperatures were measured continuously before and after complete sympathetic nerve block by extradural anaesthesia in conscious dogs in environmental temperatures slightly below (22.4 (SEM 0.4) °C) and slightly above (27.2 (0.4) °C) the thermoneutral range. In the cold environment, skin temperature increased in the distal (+2.13 °C, P < 0.001) and proximal (+ 1.1 °C, P < 0.02) front limbs and distal (+3.25 °C, P < 0.001) and proximal (+ 1.72 °C, P < 0.001) hind limbs, but decreased on the chest (-0.83°C, P < 0.001) and abdomen (-0.67 °C, P < 0.002). Similar changes (all significant) were seen in the warm environment, although the effects were smaller. Rectal temperature did not change during the experiments. Arterial pressure decreased in both groups after denervation, but was the same in the denervated state regardless of ambient temperature. Our results are incompatible with increased sympathetic discharge from unblocked regions being a dominant factor in the decrease in trunk skin temperature above and within the analgesic areas, and demonstrate a substantial contribution of the sympathetic nervous system to the maintenance of the normal skin temperature gradient along the long axis of the body. © 1988 British Journal of Anaesthesia.