[Circulatory and metabolic disturbances in accidental hypothermia (author's transl)].

Abstract

This work sums up several studies: clinical observation (electrocardiogram, cardiac rhythm, circulatory state), and biology (glycemia, blood oxygenation, acid-base balance) in 24 cases of accidental hypothermia, not related to poisoning by central nervous system depressive agents; haemodynamics in 18 of these cases; pathology of the myocardium in 11 cases; haemodynamics and microscopy of the myocardium in dogs with slowly induced or prolonged hypothermia; finally an electron microscope study in hypothermic rats. Electrocardiographic study and continuous monitoring of cardiac rhythm and tracing show, in addition to well known manifestations (bradycardia, lenghtening of QT, J wave), acute dysrhythmias, particularly circulatory arrests by asystole during or even 72 hours after rewarming. The clinical haemodynamic changes, measurable (cardiac output, mean arterial pressure, central venous pressure), or computable (stroke volume, peripheral resistances) are observed during rewarming. Several haemodynamic developments can be distinguished: --favourable evolution when the initial disturbances (decrease in cardiac output and in stroke volume, increase in peripheral resistances) disappear without any therapeutic support: --haemodynamic developments showing at a certain time evidence of hypovolemia requiring only moderate vascular replacement; --haemodynamic developments showing myocardial damage. In some cases, only hypothermia accounts for these. In circulatory arrests during or after rewarming, these haemodynamic disturbances raise the hypothesis of severe cardiac changes due to hypothermia itself.