Enhanced Susceptibility to Fever After Subarachnoid Hemorrhage
Background: Fever exacerbates ischemic neuronal injury and may adversely affect outcome after stroke. Unexplained or “central” fever is a particularly common and poorly-understood phenomenon after stroke. Risk factors for fever in critically-ill stroke patients are poorly defined. Methods: We prospectively studied the frequency and causes of fever, defined as a patient’s first temperature ≥101° F (38.3° C), among 387 patients admitted to our NICU over a 4 month period. The cause of fever was evaluated using a standard protocol in all patients. After identifying risk factors for infectious and unexplained fever in a logistic regression analysis, we calculated disease-specific adjusted odds ratios for developing each type of fever among 12 diagnostic groups, including cerebral infarction (INF), intracerebral hemorrhage (ICH), and subarachnoid hemorrhage (SAH). Results: Fever developed in 23% (87/387) of patients; 52% of fevers were related to infection, and 28% were unexplained despite a complete diagnostic evaluation. Fever occurred in 65% of patients with SAH (n=41), 31% with ICH (n=43), and 27% with INF (n=25). NICU length of stay (LOS) was a risk factor for both infectious and unexplained fever (P<.004); other risk factors included depressed level of consciousness (LOC) (P=.048) and intubation (P=.01) for infectious fever, and intra-ventricular catheterization (IVC) for unexplained fever (P=.004). SAH was the only diagnosis associated with an increased risk of infectious (P=.02) or unexplained fever (P=.05) after adjusting for these risk factors. Conclusion: Fever occurs in 65% of SAH patients, a rate almost three times higher than that of other NICU patients. In NICU patients, depressed LOC and intubation are risk factors for infectious fever, and IVC is a risk factor for unexplained fever, suggesting a role for ventricular hemorrhage in the pathogenesis of “central” fever. SAH increases the risk of both infectious and unexplained fever even after accounting for these risk factors, which may reflect abnormal thermoregulation in these patients.