• Francisco Lobo and Aldara Beiras.
• Anesthesiology Department, Hospital Geral de Santo António, Porto, Portugal. xlanesth@mail.telepac.pt
• J Neurosurg Anesthesiol. 2007 Jul 1;19(3):183-9.

AbstractDifferent anesthetic techniques have been suggested for craniotomy with intraoperative awakening. We describe an asleep-awake-asleep technique with propofol and remifentanil infusions, with pharmacokinetic simulation to predict the effect-site concentrations and to modulate the infusion rates of both drugs, and bispectral index (BIS) monitoring. Five critical moments were defined: first loss of consciousness (LOC1), first recovery of consciousness (ROC1), final of neurologic testing (NT), second loss of consciousness (LOC2), and second recovery of consciousness (ROC2). At LOC1, predicted effect-site concentrations of propofol and remifentanil were, respectively, 3.6+/-1.2 microg/mL and 2.4+/-0.4 etag/mL. At ROC1, predicted effect-site concentrations of propofol and remifentanil were, respectively, 2.1+/-0.3 microg/mL and 1.8+/-0.3 etag/mL. At NT, predicted effect-site concentrations of propofol and remifentanil were, respectively, 0.9+/-0.3 microg/mL and 1.8+/-0.2 etag/mL. At LOC2, predicted effect-site concentrations of propofol and remifentanil were, respectively, 2.1+/-0.2 microg/mL and 2.5+/-0.2 etag/mL. At ROC2, predicted effect-site concentrations of propofol and remifentanil were, respectively, 1.2+/-0.5 microg/mL and 1.4+/-0.2 etag/mL (data are mean+/-SE). A significative correlation was found between BIS and predicted effect-site concentrations of propofol (r=0.547, P<0.001) and remifentanil (r=0.533, P<0.001). Multiple regression analysis between BIS and propofol and remifentanil predicted effect-site concentrations at the different critical steps of the procedure was done and found also significative (r=0.7341, P<0.001).

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