Effect of morphine on respiratory drive in trigger ventilated pre-term infants

The response to morphine (100 microgram (mu g)/kg bolus, 10 mu g/kg/h infus ion) of 14 babies (median birth weight/gestation 1.37 kg/30 weeks) trigger ventilated for hyaline membrane disease was compared to a group of 26 babie s (median birth weight/gestation 1.1 kg/28 weeks) also trigger ventilated f or hyaline membrane disease but not treated with morphine. The effect of mo rphine on triggered breath rate was very variable with no significant diffe rence between the groups seen until 12 h after starting the infusion (mean [95% CI] difference = - 17 [-33, -2] breaths/nnin). In those babies (n = 11 ) who had plasma morphine levels measured there was no significant reductio n in triggered rate over time despite significantly increasing plasma morph ine levels. Babies who produced morphine-6-glucuronide at 12 h showed a sig nificantly greater reduction in triggered breath rate than those who did no t (median change - 22 breaths/min compared to - 4 breaths/min). (C) 2000 El sevier Science Ireland Ltd. All rights reserved.