Thermoregulatory responses to cooling in patients susceptible to malignant hyperpyrexia.

The influence of 1 h of surface cooling on body temperature, variables which contribute to thermoregulation and selected hormones and metabolites has been investigated in seven patients susceptible to malignant hyperpyrexia (MH) and in seven matched control subjects. Cooling was achieved using a liquid conditioned coverall worn next to the skin. Skin temperature decreased similarly in both groups of subjects. Heat production increased in both groups, with a slightly higher heat production being seen in the MH group. Core temperature increased in both groups of subjects at the start of the cooling period, with a significantly greater increase occurring in the MH group (control: + 0.13 +/- 0.13; MH: + 0.28 +/- 0.10 degrees C, P less than 0.05). There were no significant changes in plasma lactate, or pyruvate concentrations. Plasma glucose concentrations were lower in the control group; after 30 min of cooling plasma glucose was 4.25 +/- 0.37 mmol litre-1 in the control group and 5.34 +/- 0.21 mmol litre-1 in the MH group (P less than 0.05). There were no significant changes in plasma thyroxine or adrenaline concentrations. Plasma noradrenaline increased in both groups of subjects. The increase in plasma noradrenaline of the MH patients was greater than in most of the control subjects.