The low normothermia concept--maintaining a core body temperature between 36 and 37 degrees C in acute stroke unit patients

Abstract

Elevated body temperature increases mortality and worsens outcome in acute stroke patients. In animal models of stroke, even slight hypothermia was shown to be neuroprotective. Pharmacological treatment alone (paracetamol, metamizol) usually fails to lower core body temperature below 37 degrees C. The purpose of this study was to establish the feasibility and safety of continuous body surface cooling towards low normothermic temperatures in noncomatose, nonventilated stroke unit patients. Eighteen acute stroke patients (15 ischemic infarcts, 3 hemorrhages) with baseline body core temperatures >37.0 degrees C (taken in the urinary bladder) were laid on a water-perfused cooling mattress and received pethidine and dihydroergotoxine in order to avoid shivering and peripheral vasoconstriction. The target range for core body temperature was between 36 and 37 degrees C for 24 hours. None of the patients was treated with antipyretic drugs during the cooling period. Median baseline National Institutes of Health Stroke Scale score (NIHSSS) was 15.5 (8-24). Three patients had core temperatures >38 degrees C. A temperature in the target range could be reached within 3.3 hours (median) and maintained in all but two patients. Major procedure-related adverse events were vomiting (n = 2), drop in mean arterial blood pressure >20% (n = 2), pneumonia (n = 2), and a rise in central venous pressure >20 cm H2O (n = 3) totaling 9 events in 8 of 18 patients (44%). No patient died within the first week; mortality after three months was 12%. Continuous body core temperature reduction of 1-2 degrees C may safely be attained by a cooling mattress in nonventilated stroke unit patients. Critically high temperature values can be avoided. The neuroprotective potential of this method has to be assessed in a controlled trial.