The epidemiology of spontaneous fever and hypothermia on admission of brain injury patients to intensive care units: a multicenter cohort study

Abstract

Brain injuries from stroke and head trauma are leading causes of morbidity and death in the world. 3,27 In patients with these injuries, early fever 9 and hypothermia 13,29 (dysthermia) and the onset of systemic complications are associated with poor outcomes. Plausible theories of the underlying reasons for disturbance in thermoregulation after brain injury are based on observations in animal models. These findings suggest that potential causes of fever include damage to the hypothalamus, midbrain, or pons by enhanced sympathetic activity; acute or delayed ischemia; toxic blood metabolites; physical distortion; or inflammation.7,34 Accordingly, dysfunction of or damage to these thermoregulatory pathways is common in patients with brain injuries, putting them at increased risk for dysthermia. 7,30,34 Because dysthermia is known to be associated with poor outcomes in all forms Object. Fever and hypothermia (dysthermia) are associated with poor outcomes in patients with brain injuries. The authors sought to study the epidemiology of dysthermia on admission to the intensive care unit (ICU) and the effect on in-hospital case fatality in a mixed cohort of patients with brain injuries.Methods. The authors conducted a multicenter retrospective cohort study in 94 ICUs in the United States. Critically ill patients with neurological injuries, including acute ischemic stroke (AIS), aneurysmal subarachnoid hemorrhage (aSAH), intracerebral hemorrhage (ICH), and traumatic brain injury (TBI), who were older than 17 years and consecutively admitted to the ICU from 2003 to 2008 were selected for analysis.Results. In total, 13,587 patients were included in this study; AIS was diagnosed in 2973 patients (22%), ICH in 4192 (31%), aSAH in 2346 (17%), and TBI in 4076 (30%). On admission to the ICU, fever was more common among TBI and aSAH patients, and hypothermia was more common among ICH patients. In-hospital case fatality was more common among patients with hypothermia (OR 12.7,) than among those with fever (OR 1.9, 95% CI 1.7-2.1). Compared with patients with ICH (OR 2.0, 95% CI 1.8-2.3), TBI (OR 1.5, 95% CI 1.3-1.8), and aSAH (OR 1.4, 95% CI 1.2-1.7), patients with AIS who developed fever had the highest risk of death (OR 3.1, 95% CI 2.5-3.7). Although all hypothermic patients had an increased mortality rate, this increase was not significantly different across subgroups. In a multivariable analysis, when adjusted for all other confounders, exposure to fever (adjusted OR 1.3, 95% CI 1.1-1.5) or hypothermia (adjusted OR 7.8, 95% CI 3.9-15.4) on admission to the ICU was found to be significantly associated with in-hospital case fatality.Conclusions. Fever is frequently encountered in the acute phase of brain injury, and a small proportion of patients with brain injuries may also develop spontaneous hypothermia. The effect of fever on mortality rates differed by neurological diagnosis. Both early spontaneous fever and hypothermia conferred a higher risk of in-hospital death after brain injury. Abbreviations used in this paper: AIS ...

Pyrexia: aetiology in the ICU

“…Among critically ill patients with an acute neurological condition, the reported incidence of fever varies between 23 and 51 % [6, 48–50]. The largest study investigating the epidemiology of fever among patients admitted to the ICU with an acute neurological condition is that of Rincon et al [6].…”

“…The largest study investigating the epidemiology of fever among patients admitted to the ICU with an acute neurological condition is that of Rincon et al [6]. Of 13,587 patients admitted to 94 ICUs in the United States, 6965 (51 %) had fever defined as a temperature of 37.5 °C or greater.…”

“…Of 13,587 patients admitted to 94 ICUs in the United States, 6965 (51 %) had fever defined as a temperature of 37.5 °C or greater. The incidence of fever was highest among patients with traumatic brain injury (60 %) or aneurysmal subarachnoid hemorrhage (54 %), and lowest among patients with acute ischemic stroke (37 %) [6]. Unfortunately, Rincon and colleagues did not report on the aetiologies of pyrexia, and therefore estimates of the occurrence of infectious and noninfectious fever in neurological patients derive from smaller studies (Table 1).…”

“…Normal body temperature is between 36.0 and 37.5 °C [1]. Elevated body temperature is detected in approximately 50 % of patients admitted to adult ICUs [2–6]. In addition to being common, elevated body temperature is associated with increased mortality in subpopulations of critically ill patients including those with acute neurological conditions [7–9], noninfectious aetiologies of pyrexia [10], and medical patients that develop pyrexia in the ICU [3].…”

Evidence-Base for Fever Interventions Following Stroke

“…Instead of being an adaptive response, in the presence of an acute neurological insult such as stroke, fever has been associated with worsened outcomes, such as larger infarct volume, higher rates of mortality, and greater disability and dependence. [1][2][3][4][5][6] The underlying mechanism for the secondary injury related to fever is the heightened inflammatory response induced by the elevation in temperature. This makes the blood-brain barrier more permeable to immune cells, leading to cerebral edema and neuronal death.…”