[Comparative study of 3 techniques for total intravenous anesthesia: midazolam-ketamine, propofol-ketamine, and propofol-fentanyl]. / Estudio comparativo de tres técnicas de anestesia total intravenosa: midazolam-ketamina, propofol-ketamina y propofol-fentanilo.

OBJECTIVE: To compare the characteristics of induction, maintenance and awakening for three techniques of combined total intravenous anesthesia (TIVA): propofol-ketamine, midazolam-ketamine and propofol-fentanyl. PATIENTS AND METHODS: Sixty patients were randomly assigned to three TIVA groups. Group 1 (n = 20) received midazolam, ketamine and vecuronium. Group 2 (n = 20) received propofol, ketamine and vecuronium. Group 3 (n = 20) received propofol, fentanyl and vecuronium. The variables compared were hemodynamic changes during induction and maintenance and upon awakening; time until awakening; and the incidence of postanesthetic complications. We also assessed whether propofol was better than midazolam at preventing the psychomimetic effects of ketamine. RESULTS: The demographic characteristics of the three groups were similar. Hemodynamic variables were most stable in group 2. Perfusion of midazolam-ketamine was accompanied by a significantly higher number of hypertensive peaks. Time to awakening was significantly shorter in Group I (11.8 +/- 5 min) than in group 2 (20.2 +/- 12.5 min); in group 2 time to awakening was 16.6 +/- 5.6 min. Eight patients in group 1, 5 in group 2 and 1 in group 3 reported having bad dreams, the difference between groups 1 and 3 reaching statistical significance. No patient experienced hallucinations and all reported satisfaction with the anesthetic technique used. CONCLUSIONS: TIVA with ketamine and propofol is comparable to the most commonly used combination of propofol and fentanyl and may be an appropriate choice when hemodynamic stability is of great importance; withdrawal 15 min before ending surgery prevents prolonged awakening. Perfusion of midazolam-ketamine is not recommendable for scheduled surgery because it induces too many hypertensive peaks. Although neither midazolam nor propofol completely prevents the psychomimetic effects of ketamine, such effects are not so severe that patients reject the anesthetic technique used.