Effects of Hypoxia on the Course of Induced Fever in Dogs and Monkeys

¹ From the Department of Physical Medicine and Rehabilitation, University of Minnesota Medical School, Minneapolis, Minnesota

Data were obtained in regard to rectal temperature, inspired pO₂, circulation, metabolic rate and hematology. Fevers ranged from 39°C to 45°C and inspired pO₂ from 25 mm Hg to 83 mm Hg during hypoxia. In control experiments on dogs with normal body temperature hypoxia resulted in a fall in body temperature, blood O₂ and CO₂ content, while pulse rate, blood sugar, plasma creatinine and hematocrit increased. The main effects of induced fever in these animals breathing air were an increase in pulse rate, plasma creatinine, blood pH, blood O₂ content, hematocrit, O₂ consumption rate and CO₂ production. Blood sugar usually decreased. Blood pressure either remained essentially constant or fell during the most rigorous experiments. Total leucocyte counts indicated a trend toward an increase and differential counts indicated a rise in the proportion of segment nuclears and a fall in the relative number of lymphocytes. Hypoxia superimposed upon fever resulted in an increase in rectal temperature in 31%, a decrease in 20% and no change in 49% of the experiments, indicating that under certain conditions hypoxia can aggravate a febrile condition by further elevating body temperature. Fever produced observable tissue damage in the heart, intestine, kidney and liver. No tissue damage could be found in the brain or skeletal muscle. In three experiments cardiac index reached a maximum at approximately 43°C rectal temperature and then fell as the temperature was increased.