Acute nociceptive pain management — branching viva

Opening — the stem

A ten-year-old weighing 34 kg is admitted to the ward overnight after emergency internal fixation of a displaced femoral fracture. A fascia iliaca regional block was placed in theatre and is working well for the lateral thigh, but he is now in pain centrally and on movement, with a numeric pain score of 7 of 10. He is opioid-naive, alert, drinking sips, and passing urine. The examiner asks you to take the analgesic plan from here. [11]

Q1. "Walk me through your first assessment and your first step on the ladder."

First, confirm a measured weight (34 kg) and score the pain — he is verbal and school-age, so a 0-to-10 numeric scale is the right tool, and his score is 7 of 10, which is moderate-to-severe. I assess the airway, breathing and circulation, check that the regional block is working and the limb is perfused, and ask about prior opioid exposure (none), renal and hepatic function, asthma, allergy and obstructive sleep apnoea. My first step is the multimodal foundation: regular paracetamol 15 mg per kg per dose — 510 mg per dose for 34 kg — every 4 to 6 h, max 60 mg per kg per day (2.04 g per day, below the 4 g per day adult cap which I check), and ibuprofen 5 to 10 mg per kg per dose — 170 to 340 mg per dose — every 6 to 8 h, max 30 mg per kg per day, given he is drinking and passing urine with no contraindication. The 2025 network meta-analysis places NSAIDs first-line for acute pain. [1] [8]

Q2. "The regional block covers the lateral thigh but he is still 7 of 10 centrally. What do you add, and at what dose?"

For moderate-to-severe pain not controlled by the non-opioid foundation, I add a titrated opioid — morphine 0.1 mg per kg intravenously, which is about 3.4 mg for a 34 kg child, given in small increments and monitored with a sedation score and respiratory rate. For ongoing postoperative pain I would set up patient-controlled analgesia with a morphine bolus of about 20 micrograms per kg (about 680 micrograms) and a 10-minute lockout, under the acute pain service protocol. I would not use codeine or tramadol — both are contraindicated in children under 12 because a CYP2D6 ultrarapid metaboliser converts the prodrug to a fatal morphine dose. [11]

Q3. "What monitoring must accompany the PCA, and why is the sedation score the primary monitor?"

The monitoring is the safety triangle: pain score, sedation score, and respiratory rate, with oxygen saturation. The sedation score is the primary safety monitor because sedation precedes respiratory depression — by the time the respiratory rate has fallen and the child is bradypnoeic, the depression is established. A typical four-point sedation score runs from easy to rouse, through easy to rouse but drifts off, to difficult to rouse and unrousable; a defined threshold — the child difficult to rouse, or a respiratory rate below the age-normal range — triggers an opioid reduction, a pause and a review. Naloxone is available on the ward. [9]

Q4. "Two hours later the nurse calls: he is difficult to rouse, respiratory rate 10, pain score now low. Diagnose and act."

This is opioid-induced respiratory depression, not well-controlled pain — the low pain score in a sedated, bradypnoeic child is a warning, not a triumph. I stimulate the child, support the airway and breathing, and hold the PCA. I give naloxone titrated to the respiratory rate, not to full reversal — the goal is a breathing child who is still comfortable, because full reversal throws him back into severe pain and he will need re-dosing. Because naloxone is shorter-acting than morphine, I monitor him for recurrence and am ready to give repeat boluses or an infusion. I then review the regimen, the concentrations and the monitoring that allowed the event, and report it. [9]

Q5. "How does the regional block change the opioid story, and what is the opioid-sparing principle here?"

The regional block abolishes transmission from a defined territory, so it carries a large share of the surgical-site pain and spares opioid exposure. The opioid-sparing principle is that the multimodal bundle — regular paracetamol and an NSAID, a regional technique, and an adjuvant such as ketamine — together reduce total opioid exposure, which improves recovery and reduces opioid-related adverse effects. The opioid is then titrated for breakthrough or moderate-to-severe pain rather than carrying the whole load. The growing use of regional anaesthesia in complex paediatric patients is one of the clearest advances in opioid-sparing care. [11] [12]

Q6. "He is ready for discharge in three days. Walk me through the wean and the discharge communication."

I wean the opioid on a planned schedule: convert the PCA to scheduled oral morphine or oxycodone, then to as-needed, then stop, keeping the regular paracetamol and ibuprofen backbone to protect the wean and avoid a rebound pain spike. At discharge I write the dose in milligrams — not millilitres alone — with a dosing syringe, a stated maximum daily dose, and a clear schedule for the weaning agent and the non-opioids. I teach back to the family: how much, how often, the daily ceiling, and to avoid combining with any other preparation that may contain paracetamol. I give a written safety-net naming the features that should bring him back — increasing pain despite the analgesia, sedation or unrousability, reduced feeding or fluids, fever, or a swollen or tight limb. The opioid-stewardship principle is that every opioid has a start date and a stop date. [8] [11]