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A842
October 14, 2007 2:00 PM - 4:00 PM Room Hall D, Area K, |
| Landiolol Shortens the Time to Loss of Consciousness by Rapid Inhalation Induction: The Second Report |
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Zen'ichiro Wajima, M.D., Ph.D., Kazuyuki Imanaga, M.D., Ph.D., Toshiya Shiga, M.D., Ph.D., Tetsuo Inoue, M.D., Ph.D., Atsuhiro Sakamoto, M.D., Ph.D. Department of Anesthesia, Chiba-Hokusoh Hospital, Nippon Medical School, Inba-mura, Chiba, Japan |
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Background: At the 2006 ASA Annual Meeting, we reported that IV landiolol administration shortens the time to loss of consciousness by vital capacity rapid inhalation induction (VCRII) and suggested that landiolol reduces anesthetic requirements. A limitation of the previous study was that cardiac output (CO) was not measured. In the present study, we measured CO. Methods: Approval for this study was obtained from the IRB, and subjects provided written informed consent. Sixty-four ASA physical status I-II patients, aged 22-58 years, who were scheduled to undergo elective surgery, were included in this study. Patients were assigned randomly to one of two groups: the control group (n=31; 41 (8) years [mean (SD)] or the landiolol group (n=31; 41 (9) years). Anesthesia was induced in all patients by means of VCRII with sevoflurane, as described previously. The VCRII method was performed as follows. Patients were preoxygenated with 100% oxygen at a flow rate of 8 L/min for 5 min via a mask and a Jackson-Rees circuit. Induction was initiated with a full 4-L reservoir bag to allow for inspiration of a full vital-capacity breath. A mixture of 5% sevoflurane and 95% oxygen was delivered by vaporizer into the circle system of an anesthesia machine. The pop-off valve was kept open at all times. After preoxygenation, patients were instructed to breathe out to residual volume and hold their breath at residual volume while the circuit was replaced with the preprimed circle system. Patients were then instructed to take a vital-capacity breath and to hold this breath as long as possible, preferably until loss of consciousness. Administration of landiolol (0.125 mg/kg/min for 1 minute and then 0.04 mg/kg/min) was initiated with the vital-capacity breath. Normal saline was administered to patients in the control group. Following the initial vital-capacity breath, patients were allowed to resume spontaneous respiration. Loss of consciousness was defined as both loss of the eyelid reflex and lack of response to the verbal command “Open your eyes.” The time to loss of consciousness was recorded. CO and cardiac index (CI) were recorded throughout the procedure. Results: Mean patient age did not differ significantly between the two groups. Mean height and weight were similar between the two groups. The time to loss of consciousness was 77 (25) sec in the control group and 62 (14) sec in the landiolol group. The difference was statistically significant (P<0.005). Both CO and CI at baseline (before anesthesia induction) were similar to values at loss of consciousness in both groups, and these parameters at baseline were similar between the two groups, and these parameters at loss of consciousness were similar between the two groups. Discussion and Conclusion: Results of this study show that IV landiolol administration shortens the time to loss of consciousness by VCRII, indicating that landiolol can reduce anesthetic requirements. In addition, the mechanism underlying the shortened time to loss of consciousness does not involve CO. Some beta-blockers can reduce anesthetic requirements in humans (1). Landiolol, a novel beta-adrenergic blocker, also has this effect. In conclusion, the results of the present study suggest that IV landiolol can potentiate the effects of sevoflurane. References: 1. Yang H, et al. Can J Anesth 2003; 50: 627-30. Anesthesiology 2007; 107: A842 |