Background: Intrathecal morphine (ITM) has been used in hopes of providing good postoperative analgesia in cardiac surgery. Little is known about its use in isolated aortic valve replacement surgery.
Objectives: To evaluate the effects of 7 µ/kg ITM administration in aortic valve replacement in regards to hemodynamics, pain score, and postoperative complications when compared to general anesthesia alone.
Study design: A randomized, double-blind trial.
Setting: Academic medical center.
Methods: Forty-four patients, who underwent aortic valve replacement, were randomly assigned to receive ITM, before the induction of general anesthesia (ITM group, n = 22) or no intrathecal injection i.e., general anesthesia alone (control group, n = 22). Induction of anesthesia was done with fentanyl, propofol, and isoflurane. Pain scores, determined by visual analog scale (VAS), were recorded immediately after extubation, at the first, sixth, twelfth, eighteenth, and twenty-fourth hour after extubation. Hemodynamics, heart rate, mean arterial pressure, central venous pressure, pulmonary capillary wedge pressure, and cardiac index were recorded intra-operatively and up to 24 hours post-operatively.
Results: VAS scores were lower in the ITM group at each measured time than control group (P < 0.01). The cumulative fentanyl consumption during the first 24 hours after extubation was significantly reduced by 35% in the ITM group (951 µg /first 24 hours) as compared to the control group (1463.6 µg /first 24 hours), (P < 0.001). The mean time to first request for rescue analgesia was significantly prolonged in the ITM group (20.11 ± 4.24 hours, P < 0.001) compared with the control group (0.60 ± 0.44 hours). The mean tramadol consumption dose was significantly reduced in the ITM group (279.33 ± 61.35 mg), compared with the control group (895 ± 106.42 mg), (P < 0.001). Hemodynamic parameters exhibited a significant decrease in HR and MAP in the ITM group, but no significant difference was found in regards to CVP, PCWP, and CI. Glyceryl trinitrate consumption in the first 24 hours was significantly reduced by 43% in the ITM group (28.3 mg /first 24 hours) when compared to the control group (145.5 mg /first 24 hours), (P < 0.001). Extubation time (4.5 ± 7.5 vs. 5.3 ± 1.0 hours, P < 0.05) and intensive care unit length of stay (3.7 ± 1.0 vs. 5.6 ± 1.6 days, P < 0.01) were shorter in the ITM group.
Limitations: Small sample size.
Conclusions: In valvular heart disease patients undergoing aortic replacement surgery, ITM is a good adjunct to general anesthesia as a safe and effective analgesic alternative. It provides better hemodynamic control, earlier tracheal extubation, and shorter ICU stay.
Key words: Intrathecal, morphine, fentanyl, analgesia, aortic, cardiac, surgery.