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October 16, 2006
2:00 PM - 4:00 PM
Room Hall E, Area I
Emergence Time from Sevoflurane and Propofol Anesthesia Co-Administered with Dexmedetomidine
Norimasa Ohtani, M.D., Yutaka Yasui, M.D., Kohtaro Kida, M.D., Kasuhiro Shoji, M.D., Eiji Masaki, M.D., Ph.D.
Department of Anesthesiology, Jikei University School of Medicine, Tokyo, Japan
Background: Dexmedetomidine (Dex) has anesthetic and analgesic sparing properties and provides excellent hemodynamic stability during the stressful extubation period. Because of these properties, it is expected that Dex is beneficial also in anesthetic managements requiring smooth emergence such as those in craniotomy and in operations in patients with cardiovascular diseases. The emergency time of the general anesthesia, which might be affected by intraoperative use of Dex with general anesthetics, is an important concern in the efficient management of the operating room. We therefore addressed the issue how dexmedetomidine influences the emergence times of sevoflurane (Sevo) and propofol (Propo) that are in general short when administered alone. For this purpose, 1) we compared the emergence time in patients anesthetized with Sevo and Propo, both co-administered with Dex and, 2) to elucidate the mechanism of interaction between these drugs, we examined the influence of Dex to the effects of Sevo and Propo on the membrane currents in neurons of the locus coeruleus (LC), a nucleus playing the principal role in the sedative effect of Dex, in the rat brain slice.

Methods: 1) With approval of our institutional Human Ethics Committee and written informed consent, 40 patients being scheduled for lower abdominal surgery were randomly divided into 4 groups to receive either Sevo (0.5-1.5%) without and with Dex (1 µg/kg over 10 min followed by 0.4 µg/kg/h until the end of surgery; groups S and SD, respectively) or Propo (2-5 mg/kg/hr) without and with Dex (groups P and PD, respectively) as maintenance general anesthetics. BIS values were kept within 45 ± 5 by changing concentration of Sevo or infusion rate of Propo in all groups. Time between drug interruption and eye opening was measured. 2) Whole–cell currents of LC neurons were recorded in pontine slices prepared from young rats. Sevo and Propo were applied in the presence of dexmedetomidine. The data were analyzed by using ANOVA with subsequent intragroup comparisons made by Fisher's PLSD.

Results: 1) The emergence time of group SD was by only a few minutes longer than that of group S, whereas that of PD (29 ± 5.1 min; mean ± SEM; n=10) was 20.3 min longer than that of group P (8.7 ± 1.5 min). The emergence time in group PD was significantly (P<0.05) longer than those in other three groups. 2) In the presence of Dex (3 nM), Sevo (0.5 mM) induced inward currents (18.7 ± 9.2 pA; mean ± SEM; n=5), whereas Propo (30 mM) induced outward currents (16.9 ± 3.4 pA; n=4) (figure1), indicating that Sevo, unlike Propo, increases excitability of LC neurons even in the presence of Dex.

Conclusions: When co-administered with Dex, anesthesia with Sevo provided faster recovery from the same BIS values than that with Propo, presumably resulting from their differential effects on the excitability of neurons in the LC, a nucleus maintaining the conscious level. These results point to a beneficial synergy of Sevo and Dex in the efficient operation room management.[figure1]

Anesthesiology 2006; 105: A1035
Figure 1