Potassium distribution and toxicity in hypothermia

¹ Department of Physiology, Baylor University College of Medicine, Houston, Texas

Ten dogs were anesthetized with a combination of morphine and pentobarbital. Control arterial samples for serum potassium determinations were taken, and the animals were cooled to a mean rectal temperature of 27.9°C. At this point, a slow infusion of potassium chloride was started and was continued until the disappearance of the P wave on the continuously recorded electrocardiogram. Thirty minutes were allowed for equilibration. The apparent volume of distribution of potassium in these animals averaged 73% of the body weight. These values compared closely with values of 67% for normothermic animals receiving the same anesthetics and the same total amounts of potassium, but are lower than in similar animals given larger doses of potassium. Hypothermia lowered the lethal concentration of potassium in the serum to 8.9 mEq/l.