Effect of age factor on analgesic efficacy of morphine during recovery from remifentanil-based anesthesia in pediatric patients undergoing minor surgery

Abstract

Objective To evaluate the effect of age factor on the analgesic efficacy of morphine during recovery from remifentanil-based anesthesia in pediatric patients undergoing minor surgery. Methods Fifty pediatric patients of both sexes, aged 3-10 yr, with body mass index ≤30 kg/m2, of American Society of Anesthesiologists physical status Ⅰor Ⅱ, scheduled for elective tonsillectomy, were divided into preschool group (3-5 yr, n=30) and school-age group (6-10 yr, n=20) according to age.Anesthesia was induced by inhaling 8% sevoflurane and IV morphine 0.1 mg/kg.Pediatric patients were mechanically ventilated after tracheal intubation, and end-tidal pressure of carbon dioxide was maintained between 35-45 mmHg.Anesthesia was maintained by inhalation of 2%-3% sevoflurane and IV infusion of remifentanil 0.2 μg·kg-1·min-1.Pain was evaluated using Faces Pain Scale (FPS) and Face Legs Activity Cry Consolability (FLACC) scale during the recovery period in the postanesthesia care unit.When FPS or FLACC scores ≥4, morphine 0.05 mg/kg was intravenously injected.When pain was still unrelieved after morphine was given for 2 times (time interval 5 min), fentanyl 1 μg/kg was intravenously injected until FPS and FLACC scores <4.The requirement for analgesics and consumption of analgesics (fentanyl consumption was converted into morphine consumption) were recorded.The development of nausea and vomiting, pruritus and respiratory depression was also recorded. Results Compared with preschool group, the requirement for analgesics and consumption of analgesics were significantly decreased during recovery from anesthesia (P 0.05). No pruritus or respiratory depression was found in two groups. Conclusion The analgesic efficacy of morphine is affected by age factors during recovery from remifentanil-based anesthesia in pediatric patients undergoing minor surgery, and morphine produces better analgesic efficacy in school-age pediatric patients than in preschool pediatric patients. Key words: Age factors; Morphine; Piperidines; Child; Analgesia