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Infant pupillary response to methadone administration during treatment for neonatal abstinence syndrome: a
Sarah H Heil1, Diann E Gaalema, Anne M Johnston
1Department of Psychiatry, University of Vermont, USA. sarah.heil@uvm.edu
Insights
Infant pupil diameter reliably indicates opioid effects, mirroring adult responses. This objective measure aids in assessing neonatal abstinence syndrome (NAS) treatment.
Area of Science:
- Neonatal pharmacology
- Ophthalmology
- Pediatric critical care
Background:
- Pupil diameter is an established pharmacodynamic marker for opioids in adults.
- This metric has not been previously studied in infants.
- Assessing opioid effects in neonates could enhance treatment for those exposed to opioids in utero.
Purpose of the Study:
- To investigate changes in pupil diameter in infants treated for neonatal abstinence syndrome (NAS).
- To determine the feasibility of using pupil diameter as an objective measure of opioid effects in neonates.
Main Methods:
- Ten infants (2-7 days old) undergoing methadone treatment for NAS were enrolled.
- Pupil and iris diameters were measured from digital photographs taken at specified intervals post-dosing.
- Relative pupil diameter (pupil size as a percentage of iris size) was analyzed.
Main Results:
- A significant decrease in relative pupil diameter was observed immediately after opioid dosing (41% to 29%).
- A significant increasing trend in relative pupil diameter was noted over 10 hours post-dosing.
- Results indicate a dose-dependent and time-sensitive response to opioids.
Conclusions:
- Neonatal pupils exhibit a sensitive and predictable response to opioids, similar to adults.
- Pupil diameter offers a sensitive, objective method for evaluating neonatal opioid exposure.
- This measure may supplement or replace subjective clinical scales in NAS management.
Background:
Pupil diameter is a frequently assessed objective index of the pharmacodynamic effects of opioids in adults, but to our knowledge has never been examined in infants. Such a measure could improve assessment and treatment of neonates exposed to opioids in utero. The present study examined changes in pupil diameter after opioid administration in opioid-exposed infants who required pharmacological treatment for neonatal abstinence syndrome (NAS) to test the feasibility of using pupil diameter as a measure of opioid effects in these infants.
Methods:
Ten infants (2-7 days old) receiving methadone (0.4-0.5 mg every 12 h) for the treatment of NAS participated. A picture of one of each infant's eyes was taken under controlled illumination conditions with a standard digital camera just prior to dosing and 0-1, 2-4, 5-7, and 8-10h after dosing. The diameters of the pupil and iris were measured and relative pupil diameter (pupil diameter expressed as a percentage of iris diameter) was analyzed.
Results:
Mean (±SE) relative pupil diameter decreased significantly after dosing from 41±2% to 29±2%. After dosing, a significant increasing linear trend was observed over time, with values of 29±2%, 33±3%, 38±3%, and 41±3% at 0-1, 2-4, 5-7, and 8-10h after dosing.
Conclusions:
Infant pupils respond to opioid administration in the same sensitive, orderly manner as is commonly observed in adults. Pupil diameter appears to be an objective, sensitive measure of neonatal response to opioids that may be a useful complement to, or perhaps at times a replacement for, observer-rated scale scores.
