Effect of excessive environmental heat on core temperature in critically ill patients. An observational study during the 2003 European heat wave.
BACKGROUND
The primary goal of this study was to investigate the relation between the core temperature of critically ill patients and hot ambient temperatures during a heat wave. The second goal was to evaluate the impact of such a heat wave on the number of microbiological tests ordered.


METHODS
During a heat wave, from August 3 to 22, 2003, we conducted an observational study in the surgical intensive care unit (ICU) of a French hospital that had no air-conditioning at the time. The core temperature of 18 critically ill patients and 36 health-care workers was measured with a non-contact, infrared tympanic membrane thermometer. The association between the core body temperature in infected and non-infected critically ill patients and the staff members, and the ambient temperature in the ICU was analysed using linear regression. The number of microbiological tests ordered was also recorded and compared with the same period in the previous year.


RESULTS
The equation of the regression line for infected critically ill patients was: core temperature=33.5+0.16 x ambient temperature (R(2)=0.53; P<0.0001). The regression line was steeper than that for the non-infected patients (0.077; P<0.0001). The slopes of the regression lines for non-infected and control patients were similar (P=0.20). More blood cultures were carried out during the heat wave than at the same period during the year 2002 (4.80 blood cultures per 1000 patient-days vs 2.47 per 1000 patient-days; P=0.0006).


CONCLUSIONS
During a sustained high ambient temperature, hyperthermia can occur in critically ill infected patients and to a lesser extent in non-infected patients and health-care workers. The number of blood cultures requested rises substantially, leading to increased costs. Installation of air-conditioning is therefore recommended.
Réanimation chirurgicale et traumatologique, Service d'Anesthésie-Réanimation, AP-HP Hôpital Henri Mondor and Université Paris XII, 51 Avenue du Maréchal de Lattre de Tassigny, 94010 Créteil Cedex, France. francois.stephan@hmn.ap-hop.paris.fr
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F
Stéphan
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S
Ghiglione
F
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Decailliot
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L
Yakhou
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Duvaldestin
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Legrand
D000328:Adult; D001831:Body Temperature / Q000502:physiology*; D001833:Body Temperature Regulation; D016638:Critical Illness / Q000628:therapy*; D003428:Cross Infection / Q000175:diagnosis / Q000209:etiology; D005260:Female; D005334:Fever / Q000209:etiology* / Q000503:physiopathology; D006358:Hot Temperature / Q000009:adverse effects*; D006801:Humans; D007362:Intensive Care Units; D016014:Linear Models; D008297:Male; D008828:Microbiological Techniques / Q000706:statistics & numerical data; D008875:Middle Aged; D010297:Paris; D011446:Prospective Studies