Control of fever in septic shock: should we care or intervene?

Respective impact of lowering body temperature and heart rate on mortality in septic shock: mediation analysis of a randomized trial

PURPOSE

We previously showed that external cooling decreases day 14 mortality in febrile septic shock. Because cooling may participate in heart rate control, we studied the respective impact of heart rate and temperature lowering on mortality.

METHODS

Post hoc analysis of the Sepsiscool randomized controlled trial database (NCT00527007). Cooling was applied to maintain normothermia (36.5-37 °C) during 48 h. We assessed the time spent below different thresholds of temperature and heart rate on day 14 mortality. The best threshold was selected by AUC-ROC and tested as a potential mediator of mortality reduction. Mediation analysis was adjusted for severity and treatments influencing temperature and heart rate evolution. Sensitivity analysis was done using only patients with appropriate antimicrobial therapy.

RESULTS

A total of 197/200 patients with adequate heart rate and temperature monitoring were analyzed. The best threshold differentiating survivors and nonsurvivors was 38.4 °C for temperature and 95 b/min for heart rate. During the 48 h of intervention, cooling significantly increased the time spent with a temperature below 38.4 °C, p = 0.001, and with a heart rate below 95 b/min, p < 0.01. The longer was the time spent with a temperature below 38.4 °C, the lower was the mortality [adjOR 0.17 (0.06-0.49), p = 0.001]. The time spent with a heart rate below 95 b/min was similar in survivors and nonsurvivors [adjOR 0.68 (0.27-1.72), p = 0.42]. Mediation analysis showed that the time spent with a temperature below 38.4 °C was a significant mediator of mortality.

CONCLUSION

The time spent with a temperature below 38.4 °C was independently associated with patient's outcome and explained 73% of the effect of the randomization on the day 14 mortality. Heart rate lowering was not a mediator of mortality.

Pharmacotherapy of fever control among hospitalized adult patients

INTRODUCTION

Fever is common and associated with increased mortality among hospitalized adults. This article will review the pharmacotherapy of commonly prescribed antipyretic drugs including the rationale for and against temperature control in febrile adults, as well as the evidence associated with fever control in specific patient populations.

AREAS COVERED

Though fever is common, the molecular basis of pyrexia, and the interaction of these pathways with commonly prescribed antipyretic drugs are not fully understood. Furthermore, while experimental and clinical studies clearly demonstrate that pyrexia is harmful in select patients, available clinical trial data are unable to suggest an evidence-based approach to the treatment of fever. Interestingly, this also applies to patients with an acute neurologic injury wherein the treatment of fever with antipyretic therapy has become a common management strategy.

EXPERT OPINION

Few adequately powered clinical trials have investigated temperature control strategies in febrile patients. Therefore, it is not possible to define an evidence-based approach to the control of fever in hospitalized adults. Further clinical and translational research is required to identify the patients most likely to benefit from a strategy of fever control versus permissive hyperthermia, and to determine the antipyretic therapies associated with the greatest improvement in outcome.