The opioid-exposed newborn with evolving withdrawal — methadone maintenance

Clinical information for the examiner

Setting: Tertiary postnatal ward, 48 hours after an uneventful vaginal delivery at 36 weeks. The mother is on a supervised methadone maintenance programme at 90 mg/day and is stable; she has been rooming-in and breastfeeding since birth. She is HIV-negative and does not smoke. [9]

On your arrival:

• Axillary temperature 37.0 C; heart rate 158; respiratory rate 64. [3]
• High-pitched cry, fine tremor when handled, mildly increased tone, sweating over the brow, nasal stuffiness. [1]
• The infant last fed 90 minutes ago and took only a fraction of the expected volume; the mother reports fractured sleep. [7]
• Bedside glucose 2.2 mmol/L. [3]

Task 1 — Mechanism and timing (3 marks)

The candidate should explain the neuroadaptive mechanism. [3]

1. Mechanism: chronic in-utero opioid exposure up-regulates μ-receptors and locus-coeruleus noradrenaline; cord clamping removes the opioid brake and the unopposed noradrenergic and CNS overdrive produces the triad of CNS hyperexcitability, autonomic overdrive and GI dysregulation. [3]
2. Timing: methadone, with its long half-life, characteristically peaks at 48–72 hours — which is why this infant is declaring now and why methadone-exposed infants are observed for at least 5–7 days. [3]
3. Glucose: thermogenesis and withdrawal consume glucose, and feeding dysfunction threatens intake, so the low glucose is both a mimic to exclude and a consequence to treat. [3]

Pass criterion: candidate links the methadone exposure to the late-peaking neuroadaptive withdrawal and explains the low glucose. [3]

Task 2 — Assessment: Eat, Sleep, Console (3 marks)

The candidate should apply the functional assessment. [7]

• Eat: the infant took only a fraction of the expected volume — the eat goal is failing. [7]
• Sleep: the mother reports fractured sleep — the sleep goal is failing. [7]
• Console: not yet fully assessed, but the irritability suggests it will be challenging. [7]
• The candidate should state that because the functional goals are failing, the next step is to intensify non-pharmacologic care first, and reach for morphine or buprenorphine only if that fails. [7]
• The candidate should contrast this with the Finnegan NASS (21 items, treat if single ≥8 or three consecutive ≥24) as the score-driven alternative. [1]

Pass criterion: candidate applies the three functional questions and states the treatment decision flow, and names the Finnegan thresholds. [7] [1]

Task 3 — Immediate management and mimics (3 marks)

The candidate should manage and exclude mimics. [3]

• Correct the glucose: give a dextrose bolus (typically 2 mL/kg of 10% dextrose) and start a continuous infusion, then recheck. [3]
• Exclude mimics: check electrolytes (calcium, magnesium), perform a septic screen if the infant is unwell, and consider imaging if seizures or abnormal neurology develop. [3]
• Intensify non-pharmacologic care: low-stimulation environment, swaddle, skin-to-skin, lactation support, continue rooming-in and demand breastfeeding. [9]
• Escalate to pharmacotherapy only if the infant still cannot eat, sleep or be consoled despite maximal conservative care. [7]

Pass criterion: candidate corrects the glucose first, excludes the mimics, and intensifies non-pharmacologic care before reaching for a drug. [3] [9]

Task 4 — Pharmacologic ladder and wean (1 mark)

The candidate should defend the drug choice. [6]

• First-line options: oral morphine or sublingual buprenorphine; the Kraft NEJM 2017 trial showed buprenorphine shortened the duration of treatment relative to morphine. [6]
• Wean: titrate to a calm, feeding, sleeping infant, then wean by 10–20% daily once stable for 24–48 h. [3]
• Adjuncts: phenobarbital only as an adjunct for polysubstance or alcohol-dominant withdrawal, never as a sole agent for pure opioid withdrawal. [3]