ETOMIDATE AND THIOPENTAL-BASED ANESTHETIC INDUCTION - COMPARISONS BETWEEN DIFFERENT TITRATED LEVELS OF ELECTROPHYSIOLOGIC CORTICAL DEPRESSION AND RESPONSE TO LARYNGOSCOPY

Study Objective: To determine whether etomidate-based induction can Pr ovide better hemodynamics than a standard thiopental sodium-based anes thetic induction. Design: Prospective, single-blind clinical trial. Se tting: Multicenter university neurosurgical operating room. Patients: 66 ASA physical status II and III inpatients undergoing neurosurgical procedures for intracranial tumor or other pathology. Interventions: P atients were divided into two groups for anesthetic induction. The fir st group (control) was divided into two subgroups, with the first subg roup receiving ''low-dose'' etomidate (LET) 0.4 to 0.6 mg/kg titrated to an electroencephalographic (EEG) spectral edge frequency (SEF) of 1 0 to 12 Hz. The second subgroup received thiopental sodium (THIO) 3 to 6 mg/kg titrated to the same EEG endpoint. The study group was given high-dose etomidate (HET) 0.5 to 1.7 mg/kg titrated to an early burst suppression pattern. Measurements and Main Results: Baseline (awake) m easurements of mean arterial pressure (MAP) heart rate (HR), and SEF w ere obtained prior to anesthetic induction that was accomplished using a small bolus plus an infusion of the induction drug titrated to the EEG target. MAP, HR, and SEF were recorded just prior to laryngoscopy and intubation (T1), 30 seconds after laryngoscopy and intubation (T2) , and 90 seconds after (T3) laryngoscopy and intubation. Times to reac h EEG endpoint, along with total dose of anesthetic given, were also r ecorded. Compared with baseline values, the THIO group had the highest increase in both HR (22.9 +/- 4.4 bpm.) and MAP (16.8 +/- 4.2 mmHg) ( p < 0.05) after laryngoscopy and intubation. The LET group also had si gnificant increases compared with the HET group that demonstrated the least hemodynamic variability. No correlations could be made between a ge and dose of induction drug. Conclusions: Etomidate-based anesthetic induction, titrated to EEG burst suppression, produced stable hemodyn amics during laryngoscopy and intubation as compared with bower dose, more ''classic'' inductions with etomidate or thiopental. (C) 1997 Els evier Science Inc.