gms | German Medical Science

60th Annual Meeting of the German Society of Neurosurgery (DGNC)
Joint Meeting with the Benelux countries and Bulgaria

German Society of Neurosurgery (DGNC)

24 - 27 May 2009, Münster

Improved cerebral autoregulation index

Meeting Abstract

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  • N. Hecht - Klinik für Neurochirurgie, Campus Benjamin Franklin, Charité - Universitätsmedizin Berlin
  • I. Fiss - Klinik für Neurochirurgie, Campus Benjamin Franklin, Charité - Universitätsmedizin Berlin
  • P. Vajkoczy - Klinik für Neurochirurgie, Campus Benjamin Franklin, Charité - Universitätsmedizin Berlin
  • J. Woitzik - Klinik für Neurochirurgie, Campus Benjamin Franklin, Charité - Universitätsmedizin Berlin

Deutsche Gesellschaft für Neurochirurgie. 60. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC), Joint Meeting mit den Benelux-Ländern und Bulgarien. Münster, 24.-27.05.2009. Düsseldorf: German Medical Science GMS Publishing House; 2009. DocP01-01

doi: 10.3205/09dgnc249, urn:nbn:de:0183-09dgnc2491

Published: May 20, 2009

© 2009 Hecht et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.



Objective: The linear correlation coefficient of PtiO2 / CPP or ICP / CPP serves as a quantitative index for the status of cerebral autoregulation, yet it is merely a surrogate marker for the true hemodynamic situation best characterized by invasive CBF measurement. Furthermore, the delay of PtiO2 change in the context of CPP change may hamper interpretation of autoregulation. To further improve the diagnostic value of an autoregulation index (AI) we compared AI PtiO2 and AI CBF before and after temporal correction to PtiO2 and CBF latency after CPP alterations.

Methods: In five Patients suffering from severe aneurysmal SAH we performed continuous multimodal neuromonitoring (MAP, ICP, CPP, PtiO2, CBF) over a period of 7–10 days after SAH. From each of these data sets we selected two one-hour intervals during which cerebral autoregulation was evidently disturbed (defined by comparison of PtiO2, CBF, and CPP with the precondition of a change in CPP>10mmHg), and calculated the time delay of PtiO2 and CBF change in the context of CPP alterations. Thereafter, the corrected and uncorrected AI PtiO2 and AI CBF were calculated as correlation coefficients.

Results: Calculation of time delay resulted in a mean PtiO2 latency of 50 seconds and CBF latency of 10 seconds. The uncorrected mean AI PtiO2 and AI CBF revealed an AI of 0.39±0.3 and 0.57±0.2, respectively. By correcting these factors by the time delay we obtained significantly higher correlations of 0.53±0.3 (AI PtiO2) and 0.62±0.2 (AI CBF). These differences were statistically significant within and between all groups.

Conclusions: We have confirmed AI PtiO2 and AI CBF as valid assessment tools for the functional status of cerebral autoregulation, and demonstrated that adjustment to the temporal latency of PtiO2 and CBF response significantly increases the correlation index. Regarding its predictive value, we believe this enhancement to be essential for further improvement of test sensitivity and specificity. By comparing both indices we demonstrated that the AI CBF should be considered as the index of choice, possibly due to its direct interrelationship with the cerebrovascular perfusion status.