Investigation on the hemodynamic alterations and their mechanism during heat stroke under hot environment

Abstract

Heat stroke model was made under artificial hot environment in 26 mongrel dogs, and hemodynamic alterations and their mechanism were investigated. When the rectal temperature rose above 41°C the stroke volume (SV) and cardiac output (CO) significantly decreased. The central venous pressure (CVP) declined at first, but increased later and rose above the control value at 43°C. The mean arterial pressure (MAP) began to decrease at 41°C, and decreased by 25.7% (P < 0.01) at 42.5°C comparison with the control value. MAP dropped dramatically (68.4 %) at 43°C. Besides, the serum concentration of potassium increased by 6.1±1.6 mg (P < 0.01) in comparison with the control value. Naloxone (0.1–0.3 mg/kg) was injected i.v. at 40. 5°C of rectal temperature. SV and CO increased markedly at 41°C and 42 °C. CVP declined significantly, and MAP showed elevation at 41°C. These findings suggested that the circulatory failure during heat stroke might be related to the increased β-endorphin release from the anterior pituitary gland and the increase of serum potassium concentration.

Keywords

heat stroke / heat stress / hemodynamic alteration / naloxone / serum potassium concentration