S(+)-ketamine/propofol maintain dynamic cerebrovascular autoregulation in humans

Purpose: This study investigates the effects of S(+)-ketamine and propofol in comparison to sevoflurane on dynamic cerebrovascular autoregulation in h umans. Methods: Twenty-four patients were randomly assigned to one of the followin g anesthetic protocols: group I (n=12): 2.5 mg(.)kg(-1.)hr(-1) S(+)-ketamin e, 1.5-2.5 mug(.)mL(-1) propofol-target plasma concentration; group II (n = 12): 2.0 MAC (4.0 %) sevoflurane. Patients were intubated and ventilated w ith O-2/air (PaO2 = 0.33). Following 40 min of equilibration dynamic cerebr ovascular autoregulation was measured and expressed as the autoregulatory i ndex (ARI), describing the duration of cerebral hemodynamic recovery in rel ation 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 de layed 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 sevoflura ne 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 phy siology.