A study of patients admitted to intensive care units for heat stroke during the Chicago heat wave of July, 1995, indicates that even the extraordinary level of weather-related mortality -- more than 600 excess deaths in nine days -- radically underestimates the real consequences of that episode. In addition to the pre-hospital deaths, nearly half of the patients admitted to Chicago-area ICUs for heat stroke died within a year, 21 percent before discharge and another 28 percent after release from the hospital.
Many of the survivors suffered permanent loss of independent function; one-third had severe functional impairment at discharge and none of them had improved after one year.
The findings are reported in the August 1 issue of the Annals of Internal Medicine.
"Unlike previous descriptions of classic heat stroke, most of the patients in this study suffered from multi-system organ dysfunction, including neurologic impairment" said Maurice Ndukwu, M.D., assistant professor of medicine at the University of Chicago Medical Center and lead author of the study. "For many patients, that dysfunction persisted long after discharge."
Physicians classify heat stroke as "exertional," triggered in healthy people by intense activity in very hot and humid weather, or "classic," which usually strikes the inactive ill or elderly during prolonged heat. In this study, most patients with classic heat stroke suffered the more profound health consequences associated primarily with exertional heat stroke. They were more likely to suffer brain, kidney, and cardiovascular damage, previously considered rare in classic heat stroke.
Another troubling finding was that because of the overwhelming number of
patients that inundated the city's emergency rooms, few patients received
optimal treatment: immersion in cool or ice water within 30 minutes. Only one of
the 58 patients in this study -- which followed every patient at 12 of the
area's 24 hospitals with classic he
Contact: John Easton
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University of Chicago Medical Center