Morphine analgesia as an alternative to general anaesthesia during laser treatment of retinopathy of prematurity

Purpose: To determine the feasibility and efficacy of morphine sedation/analgesia in the laser treatment of retinopathy of prematurity (ROP). Methods: A retrospective study was carried out on all infants who underwent laser treatment for ROP over a 7 year period. Morphine infusion commenced 6 hrs prior to treatment at a rate of 10 mu g/kg/hr. This rate increased to 20 mu g/kg/hr at the start of laser treatment. Subsequent infusion rate was titrated according to tolerance of the laser and cardio and respiratory system changes and evidence of infant distress (truncal and limb movements) up to a maximum rate of 40 mu g/kg/hr. Following treatment, morphine was weaned over 6 hrs. Infant ventilation status was recorded prior to and during morphine infusion and during laser treatment. The incidences of adverse cardiac or respiratory events occurring during laser treatment were determined. Results: One hundred and nine infants treated from 1998 to 2005 were involved in the study. One hundred and thirty-six treatments were performed and mean gestational age at the time of treatment was 36 weeks. In 130 treatments, respiratory status remained stable and was not adversely affected. Infants were mechanically ventilated because of morphine-induced apnoea during three treatments, because of poor laser tolerance during two treatments and because of post-procedure apnoea in one case. In 65 treatments, minor alterations in oxygen saturation (< 90%), bradycardia or tachycardia occurred. Conclusion: This study demonstrates that morphine analgesia can be used as an alternative to general anaesthesia.