200 - Characterization of Neonatal Abstinence Syndrome in Premature Infants

Neonatal Abstinence Syndrome (NAS) secondary to in utero opioid exposure remains pervasive. Premature infants have been observed to have a lower incidence of NAS and are thought to manifest less severe withdrawal. Studies of NAS in premature infants are lacking.

Objective:

To characterize NAS in premature infants < 35 wks estimated gestational age (EGA).

Design/Methods:

Premature infants < 35 wks EGA, transferred to the NICU at ≤ 7 days, between January 2018 and December 2022, with in utero opioid exposure and at risk for NAS were reviewed to identify substance of exposure, records of abstinence scoring if performed, pharmacologic agents dosed, and duration of pharmacologic management.

Results:

56/1,553 (3.6%) NICU admissions at < 35 wks EGA and 301/3,252 (9.2%) NICU admissions at ≥ 35 wks EGA were found to have in utero opioid exposure. Opioid exposures included methadone, buprenorphine, fentanyl, oxycodone, hydromorphone, and cocaine. Additional polysubstance exposures included benzodiazepines, methamphetamine, and tetrahydrocannabinol. The most common signs of NAS in premature infants < 35 wks EGA were irritability, sleep disturbances, and alterations in tone. 9 infants 33-34 wks EGA were assessed with modified Finnegan scores, although recognized as imprecise in this population. Two infants died of complications of extreme prematurity. 42.9% of premature infants < 35 wks EGA with NAS received pharmacologic management with low-dose morphine (n=24 of 56). Mean EGA and birthweight of infants < 35 wks EGA receiving pharmacologic management were lower than infants not-receiving pharmacologic management [31.4 vs 32.3 wks; 1709 g (SD 579) vs 1905 g (SD 542)]. 3 infants < 35 wks EGA were managed with morphine and adjunct phenobarbital; all three infants were > 33 wks gestation. The duration of low-dose morphine treatment averaged 8.9 days (SD 4.7), similar to mean durations of treatment of infants ≥35 wks (8.4 days). 3 infants received antecedent continuous sedative infusions for management of other clinical instabilities as well as signs of acute opioid withdrawal, followed by intermittent dosing. 2 infants were managed exclusively with short-duration continuous infusions.

Conclusion(s):

Mean duration of pharmacologic management of premature infants < 35 wks EGA was similar to infants ≥35 wks EGA. Additional study is needed to determine more consistent assessment of premature infants manifesting opioid withdrawal, optimal pharmacologic management, and long-term adverse outcomes specific to the population.