Introduction: Several thousands of deaths were attributed to heat stroke during August 2003 in France. To date, only a very few studies have analyzed the prognosis in the intensive care unit (ICU) of the most severely hyperthermic patients.
Method: Descriptive observational study of the patients admitted to the intensive care unit at the Lariboisière hospital in Paris, for heat stroke defined by an elevated core body temperature above 40 degrees C with central nervous system dysfunction, in the absence of other etiologies explaining the hyperthermia.
Results: In the Lariboisière hospital, an elevation in the ICU (+143%) and hospital mortality rate (+191%) were registered during August 2003, in comparison with August 2002. Fifteen patients (10 men, 5 women, median age: 57 years) were admitted to the ICU for heat stroke between the 4th and 14th of August 2003. Seven of them (47%) died. On admission, the occurrence of a pre-hospital cardiac arrest, the presence of coagulation abnormalities (reduction in prothrombin time and in platelet count) or of an elevation in plasma lactate concentration were significantly associated with the risk of death in the ICU. Conversely, age, body temperature, coma depth on admission and convulsions were not predictive of death. Neurological after effects (cerebellar syndrome, polyneuropathy and residual brain damage) were noted in 50% of the survivors.
Discussion: Although it is possible that heat alone precipitated the death of very sick people, our study clearly showed that young and valid patients died of heat stroke and suggests the possible increase in the 2003 death rate secondary to the heat wave. Moreover, it is still difficult at the moment to really appreciate the long-term consequences for survivors who presented serious neurological after effects.
Conclusion: The August 2003 heat wave resulted in an elevation of the hospital and ICU death rates in the Lariboisière hospital in Paris. Despite adequate cooling and supportive therapies, the mortality of patients admitted to the ICU for heat stroke remained elevated and the neurological after effects severe. These preliminary results should be confirmed by larger cohort studies.