Pharmacotherapy of fever control among hospitalized adult patients

Magnitude of temperature elevation is associated with neurologic and survival outcomes in resuscitated cardiac arrest patients with postrewarming pyrexia

PURPOSE

Avoidance of pyrexia is recommended in resuscitation guidelines, including after treatment with targeted temperature management (TTM). Which aspects of postresuscitation pyrexia are harmful and modifiable have not been conclusively determined.

MATERIALS AND METHODS

This retrospective multicenter registry study collected serial temperatures during 72 hours postrewarming to assess the relationship between 3 aspects of pyrexia (maximum temperature, pyrexia duration, timing of first pyrexia) and neurologic outcome (primary) and survival (secondary) at hospital discharge. Adult TTM-treated patients from 13 US hospitals between 2005 and 2015 were included.

RESULTS

One hundred seventy-nine of 465 patients had at least 1 temperature greater than or equal to 38°C. Pyrexic temperatures were associated with better survival than nonpyrexic temperatures (adjusted odds ratio [aOR], 1.54; 95% confidence interval [CI], 1.00-2.35). Higher maximum temperature was associated with worse outcome (neurologic aOR, 0.30 [95% CI, 0.10-0.84]; survival aOR, 0.25 [95% CI, 0.10-0.59]) in pyrexic patients. There was no significant relationship between pyrexia duration and outcomes unless duration was calculated as hours greater than or equal to 38.8°C, when longer duration was associated with worse outcomes (neurologic aOR, 0.86 [95% CI, 0.75-1.00]; survival aOR, 0.82 [95% CI, 0.72-0.93]).

CONCLUSIONS

In postarrest TTM-treated patients, pyrexia was associated with increased survival. Patients experiencing postrewarming pyrexia had worse outcomes at higher temperatures. Longer pyrexia duration was associated with worse outcomes at higher temperatures.

Mechanisms of fever production and lysis: lessons from experimental LPS fever

Fever is a cardinal symptom of infectious or inflammatory insults, but it can also arise from noninfectious causes. The fever-inducing agent that has been used most frequently in experimental studies designed to characterize the physiological, immunological and neuroendocrine processes and to identify the neuronal circuits that underlie the manifestation of the febrile response is lipopolysaccharide (LPS). Our knowledge of the mechanisms of fever production and lysis is largely based on this model. Fever is usually initiated in the periphery of the challenged host by the immediate activation of the innate immune system by LPS, specifically of the complement (C) cascade and Toll-like receptors. The first results in the immediate generation of the C component C5a and the subsequent rapid production of prostaglandin E2 (PGE2). The second, occurring after some delay, induces the further production of PGE2 by induction of its synthesizing enzymes and transcription and translation of proinflammatory cytokines. The Kupffer cells (Kc) of the liver seem to be essential for these initial processes. The subsequent transfer of the pyrogenic message from the periphery to the brain is achieved by neuronal and humoral mechanisms. These pathways subserve the genesis of early (neuronal signals) and late (humoral signals) phases of the characteristically biphasic febrile response to LPS. During the course of fever, counterinflammatory factors, "endogenous antipyretics," are elaborated peripherally and centrally to limit fever in strength and duration. The multiple interacting pro- and antipyretic signals and their mechanistic effects that underlie endotoxic fever are the subjects of this review.