Attenuation of cardiovascular stress with sympatholytics does not improve survival in patients with severe isolated traumatic brain injury.

Abstract

Studies have shown improved survival after traumatic brain injury (TBI) with the administration of sympatholytics, including β-blockers and clonidine, which is thought to attenuate the cardiovascular stress response. However, the use of sympatholytics has not been studied in patients with isolated severe TBI (ISTBI). We hypothesized that ISTBI patients receiving sympatholytics who demonstrated a reduction in cardiovascular stress would have improved outcomes compared with similarly injured patients without these cardiovascular changes. We reviewed the medical records of 338 ISTBI patients (head Abbreviated Injury Scale [AIS] score > 3 and associated injury AIS score < 1) admitted to a Level I trauma center from 2010 through 2014. All patients were managed according to Brain Trauma Foundation guidelines. Demographic, clinical, and survival probability data were gathered. The primary outcome was inpatient mortality. Cardiovascular stress was assessed using the rate-pressure product (RPP = systolic blood pressure × heart rate / 100) calculated both before and after sympatholytic administration. Associations between independent variables and mortality were adjusted for total hospital length of stay. Among ISTBI patients, observed mortality was 6% (n = 20), while predicted mortality by Trauma and Injury Severity Score (TRISS) was 11% (n = 38). Administration of sympatholytics was associated with reduction in RPP in univariate analysis (p = 0.035). After adjusting for length of stay, neither receipt of β-blockers nor reduction in RPP was associated with survival. Mean reduction in RPP among survivors was not different from that among nonsurvivors (-4.0% vs. -11.9%, p = 0.148). In addition, RPP reduction among patients who received sympatholytics occurred at the same rate in survivors as nonsurvivors (67% vs. 68%, p = 0.894). Severity of head injury, intraventricular hemorrhage, and any intracranial operative intervention were significantly associated with mortality. Although sympatholytic administration is associated with a significant decrease in RPP, the survival benefit seen in patients with multiple injuries with TBI is not observed among ISTBI patients. Further research on the role of sympatholysis in the management of ISTBI is warranted. Therapeutic study, level IV.