Abstract

The aim of this study was to investigate the effect of dexmedetomidine (DEX) maintenance on myocardial oxygen consumption during extubation for generally-anesthetized old patients under bispectral index (BIS) monitoring. A total of 40 patients who were subjected to thyroid operation and laparoscopic cholecystectomy under general anesthesia (ASA I or II) were randomized into the experimental (n = 20) and control (n = 20) groups. General anesthesia was induced using midazolam, etomidate, sufentanil, and vecuronium bromide and was maintained using propofol, remifentanil, and atracurium besilate. The experimental group received micropump infusion of DEX at 0.2 ug kg^-1 h^-1 from 30 min before the end of operation to the end of extubation. The control group was given physiological saline with the same volume during the same period. BIS monitors were connected. Hemodynamic indexes [systolic blood pressure (SBP), diastolic arterial blood pressure (DBP), and heart rate (HR)] were recorded, and myocardial oxygen consumption index and the recovery time of consciousness were determined. HR of the experimental group decreased from 65 ± 8 to 60 ± 5 times/min at 10 min after micropump infusion, whereas that of the control group increased from 73 ± 10 to 85 ± 12 times/min, showing a significant difference (P < 0.01). Both groups did not show significant changes in HR during the following maintenance period. The two groups showed significant differences in SBP, DBP, HR, and BIS at 1, 5, and 10 min during extubation period (P < 0.05). They did not show any significant difference in extubation score, the recovery time of consciousness, or extubation time (P > 0.05). BIS-guided DEX has a stable effect on myocardial oxygen consumption in generally-anesthetized old patients during extubation period. It has no obvious influences on extubation score and the recovery time of consciousness. Thus, 0.2 ug kg^-1 h^-1 is a proper DEX micropump infusion rate.

Key words: Bispectral index, dexmedetomidine, myocardial oxygen consumption.