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S(+)-ketamine/propofol maintain dynamic cerebrovascular autoregulation in humans
K Engelhard1, C Werner, O Möllenberg
1Klinik für Anaesthesiologie der Technischen Universität München, Klinikum rechts der Isar, Munich, Germany. k.engelhard@lrz.tu-muenchen.de
Purpose:
This study investigates the effects of S(+)-ketamine and propofol in comparison to sevoflurane on dynamic cerebrovascular autoregulation in humans.
Methods:
Twenty-four patients were randomly assigned to one of the following anesthetic protocols: group I (n=12): 2.5 mg.kg(-1)*hr(-1) S(+)-ketamine, 1.5-2.5 microg*mL(-1) propofol-target plasma concentration; group II (n=12): 2.0 MAC (4.0 %) sevoflurane. Patients were intubated and ventilated with O(2)/air (PaO(2)=0.33). Following 40 min of equilibration dynamic cerebrovascular autoregulation was measured and expressed as the autoregulatory index (ARI), describing the duration of cerebral hemodynamic recovery in relation to changes in mean arterial blood pressure.
Statistics:
Mann-Whitney U test (statistical significance was assumed when P <0.05).
Results:
Dynamic cerebrovascular autoregulation was intact in all patients with S(+)-ketamine/propofol anesthesia as indicated by an ARI of 5.4 +/- 1.1. In contrast, dynamic cerebrovascular autoregulation was significantly delayed with 2.0 MAC sevoflurane (ARI=2.6 +/- 0.7) CONCLUSION: Dynamic cerebrovascular autoregulation is maintained with S(+)-ketamine/propofol-based total iv anesthesia. In contrast, 2.0 MAC sevoflurane delayed dynamic cerebrovascular autoregulation. This supports the use of S(+)-ketamine in combination with propofol in neurosurgical patients based on its neuroprotective potential along with maintained cerebrovascular physiology.