A Randomized Controlled Trial of Intrathecal versus Caudal Morphine-Bupivacaine on Postoperative Analgesia and Cortisol Levels in Pediatric Patients
Bupivacaine on Postoperative Analgesia and Cortisol Levels in Pediatric Patients
Anesthesia Analgesia
Submitted September 2025 by Dr Stephanie Pauling
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This study compared the analgesic outcomes of caudal morphine and bupivacaine with intrathecal morphine and bupivacaine in patients aged 1-5 having general, urological and orthopaedic surgery below the umbilicus.
Forty patients (aged 1-5 and weighing at least 10kg) were recruited in a single centre in New Delhi over a year-long period, and were randomised to receive either caudal bupivacaine and morphine (“caudal group”; 0.25% bupivacaine and 40mcg/kg morphine) or intrathecal bupivacaine and morphine (“ITM group”, 0.5% heavy bupivacaine and 4mcg/kg morphine) in addition to their standardised general anaesthetic. The primary endpoint was time to a FLACC score of >=4. The secondary endpoints were the need for rescue analgesia, cortisol levels (as a surrogate for stress response) and parental satisfaction with analgesia. It produced some emphatic results - heavily in favour of intrathecal morphine.
100% of the caudal group reached a FLACC score of 4 or above in the first 24 hours, but only 25% of the ITM group did, meaning that the results were presented as Kaplan-Meier curve.
Significantly more caudal patients received rescue fentanyl intra-op and in PACU, and all of them needed post-operative paracetamol, compared with only 30% of the ITM patients. Cortisol levels were lower in the ITM group and never became elevated above baseline (though this could be attributed to the dense spinal block from the bupivacaine). Parental satisfaction with analgesia was high in the ITM group and low in the caudal group. There was no significant difference in the side effect profile between the two groups.
Strengths
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The trial was an RCT; the general anaesthetic management was standardised, and a single operator performed all the neuraxial procedures, thereby minimising inter-operator variability.
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Apart from the proceduralist (who was the PI), all the data collectors, recovery and ward nurses, and parents were blinded to the intervention.
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It demonstrated a very clear difference in favour of ITM in a previously under-studied population (young children having non-spinal surgery).
Shortcomings:
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Small, single centre study (though this allowed for good standardisation of anaesthetic technique, which consisted of intravenous midazolam premedication, an iv induction with fentanyl and propofol, paralysis and intubation, and sevoflurane maintenance to a MAC of 0.7)
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No follow up after the primary endpoint of 24 hours, which means we may have missed gathering some valuable information on the actual duration of action of ITM
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Large sex imbalance in the ITM group, which may be significant given that males and females undergo different types of surgery below the umbilicus, and also, there may be sex differences in pain perception and expression – a nebulous area which is difficult to research, especially in this age group.
Take home message
Intrathecal morphine gives longer lasting analgesia, reduces serum cortisol levels, and results in greater parental satisfaction than caudally administered morphine in children aged 1-5 undergoing infra-umbilical surgery. The demonstration of superiority of ITM over caudal morphine is generally applicable to our setting, although we should note that the conduct of the general anaesthetic component may not represent typical paediatric anaesthetic practice in Australia or New Zealand.
