Clinical Significance of Impaired Cerebrovascular Autoregulation After Severe Aneurysmal Subarachnoid Hemorrhage

Abstract

Background and Purpose— The purpose of this study was to investigate the relationship between cerebrovascular autoregulation and outcome after aneurysmal subarachnoid hemorrhage. Methods— In a prospective observational study, 80 patients after severe subarachnoid hemorrhage were continuously monitored for cerebral perfusion pressure and partial pressure of brain tissue oxygen for an average of 7.9 days (range, 1.9–14.9 days). Autoregulation was assessed using the index of brain tissue oxygen pressure reactivity (ORx), a moving correlation coefficient between cerebral perfusion pressure and partial pressure of brain tissue oxygen. High ORx indicates impaired autoregulation; low ORx signifies intact autoregulation. Outcome was determined at 6 months and dichotomized into favorable (Glasgow Outcome Scale 4–5) and unfavorable outcome (Glasgow Outcome Scale 1–3). Results— Twenty-four patients had a favorable and 56 an unfavorable outcome. In a univariate analysis, there were significant differences in autoregulation (ORx 0.19±0.10 versus 0.37±0.11, P <0.001, for favorable versus unfavorable outcome, respectively), age (44.1±11.0 years versus 54.2±12.1 years, P =0.001), occurrence of delayed cerebral infarction (8% versus 46%, P <0.001), use of coiling (25% versus 54%, P =0.02), partial pressure of brain tissue oxygen (24.9±6.6 mm Hg versus 21.8±6.3 mm Hg, P =0.048), and Fisher grade ( P =0.03). In a multivariate analysis, ORx ( P <0.001) and age ( P =0.003) retained an independent predictive value for outcome. ORx correlated with Glasgow Outcome Scale ( r =−0.70, P <0.001). Conclusions— The status of cerebrovascular autoregulation might be an important pathophysiological factor in the disease process after subarachnoid hemorrhage, because impaired autoregulation was independently associated with an unfavorable outcome.

Impairment of Cerebral Autoregulation Predicts Delayed Cerebral Ischemia After Subarachnoid Hemorrhage

“…Nevertheless, it has been shown that early dysautoregulation is predictive of poor outcome. 5,8,11,27 The present study confirms these findings in a large cohort, constituting all clinical grades of SAH patients, using noninvasive NIRS and TCD methodology. However, the temporal characteristics of autoregulatory disturbances presented here differ from previous results.…”

Short pressure reactivity index versus long pressure reactivity index in the management of traumatic brain injury

“…9,13,14,18,20,21,24,26 The specific composition of any clinical data set is therefore highly variable. This points toward the complexity of TBI, and it becomes highly difficult if not impossible to control or correct for any one of these confounding variables in outcome prediction.…”

“…Intact, partially impaired, or completely disrupted cerebral autoregulation has been reported, and various degrees of impairment have prognostic relevance. 1, 3,13,17,25,32 The pressure reactivity index (PRx), which is an index calculated from a moving correlation coefficient between mean ABP and ICP, has gained wide acceptance in ICU settings, and it has generated a large number of publications.…”

Fast blood flow monitoring in deep tissues with real-time software correlators

“…Importantly, CVAR is often impaired after brain injury; in this scenario, CBF can vary in response to MAP variation [56,57]. Moreover, the degree of CVAR impairment correlates with the initial severity of brain injury and is an independent predictor of outcome [41,56,58].…”