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(Stroke. 2007;38:981.)
© 2007 American Heart Association, Inc.

Original Contributions

Continuous Monitoring of Cerebrovascular Autoregulation After Subarachnoid Hemorrhage by Brain Tissue Oxygen Pressure Reactivity and Its Relation to Delayed Cerebral Infarction

From the Department of Neurosurgery, University of Leipzig (M.J., M.U.S., C.N., J.M.), Leipzig, Germany; and the Department of Anaesthesiology and Intensive Care Medicine, Rheinische-Friedrich-Wilhelms University (M.S.), Bonn, Germany.

Correspondence to Matthias Jaeger, Department of Neurosurgery, University of Leipzig, Liebigstrasse 20, D-04103 Leipzig, Germany. E-mail jaem{at}medizin.uni-leipzig.de

Background and Purpose— Disturbances of cerebrovascular autoregulation are thought to be involved in delayed cerebral ischemia and infarction after aneurysmal subarachnoid hemorrhage (SAH). We hypothesized that the continuous monitoring of brain tissue oxygen (PtiO₂) pressure reactivity enables the detection of impaired autoregulation after SAH and that impaired autoregulation is associated with delayed infarction.

Methods— In 67 patients after severe SAH, continuous monitoring of cerebral perfusion pressure (CPP) and PtiO₂ was performed for an average of 7.4 days. For assessment of autoregulation, the index of PtiO₂ pressure reactivity (ORx) was calculated as a moving correlation coefficient between values of CPP and PtiO₂. Higher ORx values indicate disturbed autoregulation, whereas lower ORx values signify intact autoregulation.

Results— Twenty patients developed delayed cerebral infarction, and 47 did not. Mean ORx was significantly higher in the infarction group compared with the noninfarction group (0.43±0.09 vs 0.23±0.14, respectively; P<0.0001). In a day-by-day analysis, ORx did not differ between groups from days 1 to 4 after SAH but was significantly higher from day 5 onward in the infarction group, indicating a deficit of autoregulatory capacity. In a logistic-regression model, ORx values from days 5 and 6 after SAH carried predictive value for the occurrence of delayed infarction but before this event ultimately occurred (P=0.003).

Conclusions— ORx indicates impaired autoregulation in patients who develop delayed infarction after SAH. Furthermore, this index may distinguish between patients who finally develop delayed infarction and those who do not.

Key Words: autoregulation • brain tissue oxygen • delayed ischemia • subarachnoid hemorrhage

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