Comparison of the Efficacy and Safety of Morphine and Fentanyl as Adjuvants to Bupivacaine in Providing Operative Anesthesia and Postoperative Analgesia in Subumblical Surgeries Using Combined Spinal Epidural Technique.

Introduction: The combined spinal epidural (CSE) technique involves intentional subarachnoid blockade and epidural catheter placement during the same procedure to combine their individual best features, to reduce the total drug dosage and avoid their respective disadvantages. The addition of opioids to local anesthetics (bupivacaine) for CSE anesthesia (CSEA) is increasingly common to enhance the block. Neuraxial fentanyl is more potent and has shorter duration of action than morphine which provides prolonged anesthesia and analgesia, however at the cost of increased incidence of adverse effects like delayed respiratory depression.

Aims and Objectives: The aim is to compare the efficacy and safety of morphine and fentanyl as adjuvants to bupivacaine in subumblical surgeries using CSE technique. The characteristics of sensory and motor block, intergroup variations in pain, cardiorespiratory parameters, and adverse effects were compared between the two groups.

Materials and Methods: A total of 60 patients belonging to physical status American Society of Anesthesiologists Classes I and II, aged 18-60 years were randomized into two groups: Group A ( n = 30) received intrathecal 0.5% heavy bupivacaine 12.5 mg and morphine 2.85 μg/kg; Epidural Anesthetic bolus (when required/T11Regression) 8 ml 0.25% isobaric bupivacaine and 0.04 mg/kg morphine; Epidural Analgesic bolus (postoperative visual analog scale [VAS] score >30) 5 ml 0.125% isobaric bupivacaine and 0.04 mg/kg morphine and Group B ( n = 30) received intrathecal 0.5% heavy bupivacaine 12.5 mg and fentanyl 0.35 μg/kg; Epidural Anesthetic bolus (when required/T11Regression) 8 ml 0.25% isobaric bupivacaine and 0.7 μg/kg fentanyl; Epidural Analgesic bolus (postoperative VAS score >30) 5 ml 0.125% isobaric bupivacaine and 0.7 μg/kg fentanyl.

Results and Conclusion: Group A had significantly prolonged two segment regression time, T11 regression time, lower mean VAS score, prolonged effective analgesia, and required lesser number of epidural boluses in 24 h as compared to Group B ( P < 0.001). There were no significant differences between the groups considering onset of sensory block, duration of motor block, median maximum sensory block level achieved after spinal component (T6), median highest sensory block level achieved after epidural anesthetic bolus (T7-4seg enhancement after regression to T11), cardiorespiratory parameters and adverse effects. None of the patients had respiratory depression nor was there any failure of spinal/epidural component of CSEA. Thus, addition of morphine to bupivacaine in CSEA produced prolonged effective anesthesia and postoperative analgesia compared to addition of fentanyl to bupivacaine without producing undue adverse effects.