A Randomized Controlled Trial of Intrathecal versus Caudal Morphine-Bupivacaine on Postoperative Analgesia and Cortisol Levels in Pediatric Patients

BACKGROUND: Morphine is commonly used in pediatric caudal blocks. We compared the analgesic efficacy and effect on cortisol levels of intrathecal morphine and bupivacaine with caudal morphine and bupivacaine in children undergoing lower abdominal surgeries. METHODS: Forty children undergoing lower abdominal surgeries were randomized to receive 4 μg/kg of intrathecal morphine and 0.5% hyperbaric bupivacaine (n = 20), or caudal morphine 40 μg/kg and 0.25% bupivacaine (n = 20). Postoperative analgesia was provided with intravenous (IV) paracetamol (PCM). The primary outcome was time to reach Face, Legs, Activity, Cry, and Consolability (FLACC) score ≥4 postoperatively. Secondary outcomes were perioperative serum cortisol levels, analgesic requirement, and parent satisfaction. RESULTS: Since seventy 5% of patients receiving intrathecal morphine and bupivacaine did not reach a FLACC score ≥4 within 24 hours, the primary outcome was presented as the Kaplan-Meier curve. The probability of FLACC score <4 was significantly higher with intrathecal morphine and bupivacaine than with caudal morphine and bupivacaine ( P < .001). The unadjusted and adjusted (for gender) hazard ratio (95% confidence interval [CI]) of occurrence of pain (FLACC score ≥4) was 0.07 (0.03-0.15, P < .001) and 0.06 (0.03-0.14, P < .001), respectively. The difference in means (95% CI) of cortisol levels between caudal morphine (with bupivacaine) and intrathecal morphine (with bupivacaine) groups were after intubation -0.667 (-4.99 to 3.65, P = .76), at 2 hours intraoperatively 7.88 (3.55-12.2, P < .001), 6 hours postoperatively 16.8 (12.5-21.1, P < .001), and 24 hours postoperatively 15.4 (11.1-19.7, P < .001) μg/dL. Intraoperatively, rescue fentanyl was required by 60% of patients on caudal morphine and bupivacaine against 20% of patients receiving intrathecal morphine and bupivacaine (absolute risk-reduction [95% CI] of 40% [12%-68%]; P = .010). Postoperative rescue fentanyl was required in 45% of patients on caudal morphine and bupivacaine and 5% of patients on intrathecal morphine and bupivacaine. All (100%) patients on caudal morphine and bupivacaine required postoperative PCM against 6 (30%) patients on intrathecal morphine and bupivacaine (absolute risk-reduction [95% CI] of 70% [50%-90%]; P < .001). The median (interquartile range [IQR]) parent satisfaction score for patients on caudal morphine (with bupivacaine) and intrathecal morphine (with bupivacaine) was 0(0-0) and 2(2-2) at 12 hours postoperatively ( P < .001) and 0(0-1) and 2(1.5-2) at 24 hours postoperatively ( P < .001). One patient in each group developed nausea and vomiting, and 1 patient in the intrathecal group developed pruritus. There was no incidence of respiratory depression. CONCLUSIONS: Intrathecal morphine and bupivacaine results in longer duration of analgesia, lower analgesic consumption, prevents surgical-stress-related elevation of serum cortisol, and improves parent satisfaction compared to caudal morphine with bupivacaine in children undergoing lower abdominal surgeries.