Safety profile of morphine following surgery in neonates.

OBJECTIVE

To determine the effect of morphine on duration of mechanical ventilation, apnoea and hypotension among full-term neonates who underwent thoracic or abdominal surgery in a level III neonatal intensive care unit.

METHOD: Medical records of 82 infants were reviewed retrospectively and data including patient demographics, clinical diagnosis, type of surgery, postoperative opioid administration, duration of mechanical ventilation, hypotension, apnoea and pain scores (premature infant pain profile (PIPP) score) were collected.

RESULT: Sixty-two neonates (76%) received morphine following surgery as a continuous intravenous infusion during the postoperative period. Linear regression analysis showed that morphine dosage and duration were significantly associated with the duration of mechanical ventilation. An increase in morphine infusion rate by 10 microg kg(-1) h(-1) was associated with an increase in the duration of mechanical ventilation by 24 h (P<0.0001) and an increase in morphine duration of 1 hour was associated with a longer duration of mechanical ventilation by 38 min (P<0.0001). Logistic regression analysis showed no association between morphine infusion rate or duration and hypotension. Apnoea was not associated with morphine dosage or duration of infusion in neonates receiving morphine following extubation. Score on the PIPP correlated significantly with morphine infusion rate across time (r=0.47, P<0.01).

CONCLUSION

Postoperative morphine dose and duration may prolong the duration of mechanical ventilation but there are no significant dose-dependent effects on other parameters including apnoea or hypotension following extubation in term neonates. More research is needed to determine the safety profile of morphine for management of pain in non-ventilated neonates.