Opioid stewardship and complex analgesia — branching viva

Opening — the stem

A nine-year-old girl weighing 30 kg is admitted to the ward after internal fixation of a displaced femoral fracture. She is started on a morphine patient-controlled analgesia device by the acute pain team. The examiner asks you to take the opioid-stewardship plan from here. [1]

Q1. "Set up the PCA. What are the parameters, and what surrounds it?"

I confirm a measured weight of 30 kg and a pain score first. The PCA morphine device is set to a bolus of 10 to 20 microgram per kg — 300 to 600 microgram per demand for this child — with a lockout of 5 to 10 minutes, and an optional low background infusion of 0 to 4 microgram per kg per hour. She is nine and can understand the device, so a PCA is appropriate; an infant or a child who could not use a PCA would receive nurse-controlled analgesia instead, and I would not allow parent-controlled analgesia by proxy. Surrounding the opioid I place the multimodal backbone: regular paracetamol and an NSAID where not contraindicated, a regional or local anaesthetic technique for the surgical site, an NMDA antagonist such as ketamine, and an alpha-2 agonist such as dexmedetomidine or clonidine. The explicit goal is to minimise total opioid exposure. [1] [11]

Q2. "What are you monitoring, and how does it gate the next dose?"

I monitor three numbers together at each assessment: the pain score, a structured sedation score, and the respiratory rate counted over a minute. The next PCA setting or breakthrough bolus is gated on the combination. A high pain score with a low sedation score supports giving the next dose; a low pain score with a rising sedation score supports holding it. Pulse oximetry is the floor, but for a child on a PCA with a background infusion I prefer capnography, because oximetry alone misses the hypercapnia of early opioid over-sedation. I keep naloxone at the bedside. [8]

Q3. "Two hours later the nurse finds her hard to rouse, respiratory rate 8, sedation score 3. What do you do, in order?"

I assess and support the airway and breathing first: I stimulate her, position the airway, and give bag-valve-mask support with oxygen for the slow and shallow breathing, and I call for senior and intensive-care help for a child this sedated. I reduce the PCA demand doses and keep the device at the bedside. I take a full set of observations including oxygen saturations, a bedside glucose and a temperature. Only after the airway and breathing are supported do I prepare naloxone. [8]

Q4. "Give the naloxone. Dose, route, endpoint, and reasoning."

I give naloxone intravenously in increments of 0.5 to 2 microgram per kg — about 15 to 60 microgram for this 30 kg child — repeated every two to three minutes, titrated to the respiratory rate. The endpoint is a child who is breathing adequately and is rousable, not a child who is fully awake and in pain. I titrate rather than give a single wake-up dose because a large bolus displaces the opioid all at once, throws her into acute pain and withdrawal, and wears off before the morphine — so she would be over-sedated again, now worse. The titrated approach restores the drive to breathe while preserving analgesia. [9]

Q5. "She recovers. What is the plan for the next two hours?"

I monitor her continuously for recurrence, because the opioid outlasts naloxone — naloxone's half-life is about 30 to 80 minutes against morphine's several hours. I have repeat naloxone boluses ready, or an infusion if she recurs. I review the PCA parameters and the opioid dose with the acute pain team, and I exclude two non-opioid causes of an altered child in parallel: hypoxia, with oxygen and capnography, and hypoglycaemia, with the bedside glucose. [8] [9]

Q6. "On day three she transitions to oral morphine. Walk me through the rotation."

I rotate using the equianalgesic principle — 10 mg of intravenous morphine is approximately equianalgesic to 30 mg of oral morphine — and I convert her recent total opioid exposure to an oral morphine equivalent. The crucial step the examiner wants is the incomplete cross-tolerance reduction: I reduce the calculated equianalgesic dose of the new oral opioid by 25 to 50 per cent, because a child tolerant to one opioid is not fully tolerant to another, and a straight equianalgesic conversion over-doses her. I split the reduced total into a regular dose and a breakthrough dose, I reassess at onset, and I do not use methadone — methadone conversion is non-linear and specialist-only. I write the discharge prescription for the smallest effective quantity and a disposal plan for any leftover opioid, because the home prescription is a leading entry point to misuse. [7] [10]