Closed-circuit isoflurane-based anesthesia provides better fast-tracking anesthesia than fentanyl/propofol-based anesthesia for off-pump coronary artery bypass graft surgery

Abstract

Background: In recent years, low-dose fentanyl combined with short-acting hypnotic drug has been thought to be better than traditional high-dose fentanyl in cardiac anesthesia. On the other hand, the practice of closed-circuit inhaled anesthesia offers many advantages, including hemodynamic stability, maintenance of adequate anesthesia depth and early recovery. This study sought to evaluate the effect of closed-circuit isoflurane-based anesthesia (CIA) and fentanyl/propofol-based anesthesia (FPA) on off-pump coronary artery bypass graft (OPCABG) surgery.

Methods: Fifty patients scheduled for elective OPCABG surgery were enrolled and randomly assigned to receive either CIA (n = 25) or FPA (n = 25). In the CIA group, anesthesia was induced with fentanyl 2 microg/kg and midazolam 0.05 mg/kg, followed by 2% isoflurane in oxygen (oxygen flow rate = 3 L/min) via mask ventilation for 30 min. Pancuronium 0.1-0.15 mg/kg was given thereafter to facilitate endotracheal intubation. Anesthesia was maintained by isoflurane in a minimal oxygen flow of 300 mL/min, with the vaporizer adjusted to deliver 3%-5% concentration. In the FPA group, anesthesia was induced with fentanyl 10-15 microg/kg and midazolam 0.05 mg/kg; and pancuronium 0.1-0.15mg/kg was used for endotracheal intubation. Anesthesia was maintained by propofol 2-6 mg/kg/hr and fentanyl 1-2 microg/kg/hr, and an incremental bolus of i.v. propofol 20 mg was given if the patient's mean blood pressure (MBP) exceeded 85 mmHg. An inotropic agent was given if the patient's MBP dropped below 65 mmHg or if the patient experienced a decrease in MBP greater than 20% of the preinduction value. The time of extubation, length of stay in the intensive care unit, and inotropic requirements were recorded.

Results: The patients in the CIA group were extubated earlier than those in the FPA group (281.3 +/- 32.5 min versus 311.3 +/- 38.5 min, respectively; P < 0.05), although there was no statistical difference in the length of stay in the intensive care unit (29.6 +/- 4.8 hr versus 30.1 +/- 7.6 hr, respectively; P = 0.4). The use of inotropic agent in the CIA group was less than in the FPA group (16% vs. 56%, P < 0.01). Dopamine requirement was less in the CIA group than in the FPA group (0.8 +/- 0.3 vs. 3.7 +/- 0.4 microg/kg/min, respectively; P < 0.01).

Conclusions: These results suggest that CIA, as compared with FPA, provides a significant reduction in the time to extubation after OPCABG surgery with less use of inotropic agents.