Neonatal abstinence syndrome

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Background

  • Condition caused by neonatal withdrawal from substance exposure in utero
    • Withdrawal within first 24-48 hrs → fetal alcohol syndrome
    • Withdrawal within 48-72 hrs → heroin
    • Withdrawal at 7-14 days → methadone
  • Incidence has quadrupled since 1999 from 1.5 per 1000 hospital births to 6.0 per 1000 in 2013[1]
  • Polysubstance withdrawal must also be considered

Clinical Features

  • Agitated - high-pitched cry, restlessness, tremors, hypertonia, convulsions
  • Vasomotor - sweating, fever
  • Respiratory - nasal congestion, persistent sneezing, RR > 60/min, nasal flaring
  • Metabolic - poor feeding, vomiting, loose stools

Differential Diagnosis

Evaluation

  • Pharmacologic treatment when 3 consecutive ≥ 8 on NAS(Finnegan scale
  • Enzyme immunoassay, urine toxicology, meconium analysis
  • Consider cranial ultrasound for cocaine-exposed neonates with abnormal neurologic signs

Management

  • Supportive - swaddling to decrease sensory stimulation, frequent small feedings of 24 cal/oz formula
  • Opiates when supportive measures fail
  • Morphine is 1st line for infants exposed to both opioids and benzos
    • Neonatal morphine 0.4mg/ml PO sln
      • Watch for side effect limiting dose (urinary retention)
      • Withdrawal symptoms need to be stabilized for 3-5 days before taper
      • Mother's methadone < 50mg (or other opiate)
        • Start morphine PO sln 0.1mg/kg q3hrs with feeds
        • Increase by 0.1mg/kg hourly if NAS score ≥ 8, max 1mg/kg
      • Mother's methadone > 50mg
        • Start 0.2mg/kg q3hrs
        • Increase by 0.2mg/kg hourly if NAS score ≥ 8, max 1mg/kg
    • If NPO, use preservative free morphine at 50 mcg/ml
      • Load 30 mcg/kg over 1hr, then infusion at 2 mcg/kg/hr
      • Increase by 1 mcg/kg/hr hourly until NAS < 8, max 6 mcg/kg/hr
  • Longer acting buprenorphine may significantly reduce hospital admission and treatment duration as compared to morphine[2]
    • Morphine q4 hours vs. buprenorphine q8 hours if NAS scale > 12
    • Buprenorphine dosed initially at 5 mcg/kg q8 hrs to max dose of 20 mcg/kg q8 hrs
  • Benzo withdrawal treatment
    • Midazolam 0.1mg/kg IV q3hrs or 0.3mg/kg PO q3hrs
    • OR phenobarbital 3mg/kg IV or PO q24hrs
  • Phenobarbital for seizures OR side effect limiting morphine effects OR max morphine dose reached
    • 16mg/kg load divided into two consecutive feedings for day 1
    • 24 hrs later, use 2-8mg/kg/day maintenance dose

Disposition

  • Admit

See Also

References

  1. Ko JY et al. Incidence of Neonatal Abstinence Syndrome — 28 States, 1999–2013. Weekly / August 12, 2016 / 65(31);799–802.
  2. Kraft WK et al. Buprenorphine for the Treatment of the Neonatal Abstinence Syndrome. May 4, 2017DOI: 10.1056/NEJMoa1614835.