Risk of Fatal Heatstroke After Hospitalization

To the Editor: In the August 1998 issue Dr. Nigel Bark (1) reported on a study that found significantly more deaths occurring among patients in state hospitals during heat waves than during control periods. He also reported that hospitalized psychiatric patients had twice the relative risk of dying in a heat wave compared with the general population. The risk was reduced after preventive measures were introduced throughout the state hospital system.

As a corollary to Bark's important findings, we would like to add our observations on the continuing risk of fatal heatstroke immediately after discharge from a psychiatric facility. We have been consulted recently about several cases in which psychotic patients were successfully treated in the hospital during the summer, only to die unexpectedly from heatstroke within days after discharge. These cases indicated to us that the time after discharge from an extended hospital stay may represent an important but neglected high-risk period for heatstroke.

Patients may be more vulnerable to heatstroke after hospital discharge for several reasons. First, patients who have been noncompliant with their medication before admission have a significantly reduced ability to dissipate heat once antipsychotic and anticholinergic medications are reinstituted during hospitalization (1,2,3,4,5). Second, after recovery, patients may feel more energetic and attempt to compensate for activities they missed while hospitalized. However, most clinicians and patients are unaware of how little physical activity it takes to raise body temperatures to life-threatening levels in a hot, humid environment when heat-loss mechanisms are impaired by drugs. Once sweating ceases under these conditions, a patient who is doing even moderate exercise such as walking briskly may experience a temperature rise exceeding nine degrees Fahrenheit per hour (4).

A third reason for increased vulnerability to heatstroke is that patients who have been sedentary in an air-conditioned hospital environment are neither physically conditioned nor acclimatized to the heat. Acclimatization to heat takes two weeks or more of exposure and requires complex adaptations by the cardiovascular, endocrine, renal, and exocrine systems. Finally, resumption of drug or alcohol use after discharge further increases the risk of heatstroke.

Because of the significant advances cited by Bark in the safe management of acutely ill psychiatric patients on air-conditioned inpatient units, clinicians may be unaware of the dangers of heatstroke among unacclimatized patients after a successful hospital course and discharge. Our clinical experience suggests that it may be worthwhile to investigate the mortality rate of recently discharged psychiatric inpatients specifically during heat waves. In the interim, clinicians should consider the dangers of hot, humid weather in discharge planning for these patients.

We agree with Dr. Bark that preventive measures are paramount. Although resources are often limited, patients who require assistance should be offered help in obtaining protected housing. Most important, patients, families, and caretakers should be informed about the dangers of heat, humidity, dehydration, and even mild or moderate exertion. In the absence of such precautions, recovered, medicated, and unacclimatized patients, especially those with comorbid medical or addictive disorders, are at high risk of fatal heatstroke if discharged during a heat wave.