title: Propofol and remifentanil effect-site concentrations estimated by pharmacokinetic simulation and bispectral index monitoring during craniotomy with intraoperative awakening for brain tumor resection.
abstract: Different 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).
authors.affiliation: Anesthesiology Department, Hospital Geral de Santo António, Porto, Portugal. xlanesth@mail.telepac.pt
authors.forename: Francisco
authors.initials: F
authors.lastname: Lobo
authors.forename: Aldara
authors.initials: A
authors.lastname: Beiras
mesh_terms: D000328:Adult; D000768:Anesthesia, General / Q000379:methods; D019162:Anesthetics, Combined / Q000494:pharmacology; D018686:Anesthetics, Intravenous / Q000493:pharmacokinetics*; D001932:Brain Neoplasms / Q000601:surgery*; D003198:Computer Simulation; D016292:Procedural Sedation / Q000379:methods; D003399:Craniotomy / Q000379:methods*; D004569:Electroencephalography / Q000187:drug effects; D005260:Female; D006801:Humans; D007432:Intraoperative Period; D017214:Laryngeal Masks; D008297:Male; D016343:Monitoring, Intraoperative / Q000379:methods*; D010880:Piperidines / Q000493:pharmacokinetics*; D011237:Predictive Value of Tests; D015742:Propofol / Q000493:pharmacokinetics*; D000077208:Remifentanil; D012189:Retrospective Studies; D014851:Wakefulness / Q000187:drug effects*
chemical_list: D019162:Anesthetics, Combined; D018686:Anesthetics, Intravenous; D010880:Piperidines; D000077208:Remifentanil; D015742:Propofol