Correlation of clinical outcome with pressure-, oxygen-, and flow-related indices of cerebrovascular reactivity in patients following aneurysmal SAH

Abstract

Background: Impaired cerebrovascular reactivity (CR) has been reported to be associated with adverse outcome in patients with aneurysmal subarachnoid hemorrhage (aSAH). However, CR may be determined using different paradigms and it is unclear, which measurement method most suitable reflects the clinical course or is able to predict clinical deterioration.

Methods: Twenty-one aSAH patients were included in this study. Following occlusion of the aneurysms with or without implantation of nicardipine prolonged release implants (NPRIs), mean arterial and mean intracranial pressure, regional tissue oxygenation, and regional cerebral blood flow was determined. Based on these data, pressure-, oxygen-, and flow-related autoregulatory indices (PRx, ORx, FRx) were simultaneously calculated and correlated with outcome parameters including the Glasgow outcome score (GOS) and the modified Rankin (mRankin) scale.

Results: Eight patients showed newly developed cerebral infarcts. Low values of GOS and mRankin scale highly correlated with the incidence of cerebral infarcts (GOS, P = 0.001; mRankin, P = 0.003). However, indices of CR did not differ significantly between the infarction (I) and the noninfarction group (NI) (PRx, I, 0.058 +/- 0.096, NI, 0.097 +/- 0.203, P = 0.538; ORx, I, 0.162 +/- 0.316, NI, 0.094 +/- 0.176, P = 0.690; FRx, I, 0.395 +/- 0.200, NI, 0.265 +/- 0.177, P = 0.119). No correlation was found between indices and clinical outcome parameters (all not significant). However, ORx and FRx correlated well (P = 0.016).

Conclusions: Due to the low number of included subjects, the obtained results are preliminary. However, they indicate that either the present technique of index-determination is not sensitive enough or that there is no strong relation between the measured indices and clinical outcome. Future verification is required of continuous against already established non-continuous monitoring techniques of CR in order to relate both to clinical outcome.