By Paul J. Young, Hallie C. Prescott
Fever is a pathophysiological response in which the body’s normal thermoregulatory set-point is adjusted upwards leading to an increase in body temperature. In contrast, hyperthermia occurs from excessive heat production or insufficient thermoregulation (e.g., heat stroke or drug reactions). Although temperature elevation is common in Intensive Care Unit (ICU) patients, a newly elevated body temperature should prompt consideration of a diagnostic evaluation. It is always prudent to consider the possibility of infection; however, for critically patients with acute brain pathologies in particular, elevated body temperature is common, even in the absence of infection. Body temperature may be elevated due to drugs, particularly antipsychotic, serotonergic, sympathomimetic, anesthetic, and anticholinergics drugs . Thyrotoxicosis and pheochromocytoma should also be considered in the differential diagnosis. Often elevated temperature is multifactorial and, in many patients, particularly after major surgery, a specific cause is not found.
Although body temperature is recorded assiduously in the ICU , it is often unclear when or how to intervene when a patient’s body temperature is elevated. A recent individual patient data meta-analysis reported that more active fever management did not increase survival compared with less active fever management in an all-comers population of critically ill adults . Survival by treatment group was similar in a range of subgroups defined by age, illness severity, receipt of specific organ supports, and the presence versus absence of high fever at baseline. These data suggest that, in general, when it comes to active management of fever in ICU patients, although less may not be more, doing less to treat fever results in similar outcomes to doing more.