title: Recurrent hypoxemia in young children with obstructive sleep apnea is associated with reduced opioid requirement for analgesia.
abstract: BACKGROUND
  Obstructive sleep apnea (OSA) in children is often associated with recurrent hypoxemia during sleep. In developing animals, central opioid neuropeptide content is high, and opioid receptors are up-regulated after recurrent hypoxia. The authors hypothesized that children with recurrent hypoxemia due to OSA might have altered central opioid functionality that could affect their responsiveness to opioid drugs. Using a retrospective database, we assessed the relation of age and preoperative oxygen saturation to the cumulative postoperative morphine dose administered for analgesia in children with OSA undergoing adenotonsillectomy.
  
  
  METHODS
  Inclusion criteria were (1) adenotonsillectomy for OSA; (2) no concomitant pathology; (3) intraoperative administration of short-acting opioid drugs; (4) endotracheal extubation on awakening in the operating room; and (5) morphine as the parenteral, postoperative analgesic.
  
  
  RESULTS
  Forty-six children (16 girls) fulfilled the inclusion criteria. Age and preoperative arterial oxygen saturation (SaO2) nadir, either individually (P = 0.023, P = 0.0003, respectively) or in combination (P = 0.00009), exhibited a significant correlation to the morphine dose required for analgesia. Four of these children, aged 26.5 +/- 13.2 months, with a preoperative SaO2 nadir of 70.3 +/- 12.9%, did not require any postoperative morphine for analgesia at all.
  
  
  CONCLUSIONS
  The authors speculate that the reduced morphine requirement for analgesia in children displaying oxygen desaturation associated with severe OSA may be related to their young age and to an up-regulation of central opioid receptors consequent to recurrent hypoxemia. In evaluating OSA in children, preoperative determination of the SaO2 nadir is important for predicting the postoperative opioid dosage required for analgesia.
authors.affiliation: Division of Pediatric Anesthesia, McGill University Health Centre/Montreal Children's Hospital, Montreal, Quebec, Canada. roula.cacolyris@muhc.mcgill.ca
authors.forename: Karen A
authors.initials: KA
authors.lastname: Brown
authors.forename: André
authors.initials: A
authors.lastname: Laferrière
authors.forename: Immanuela Ravé
authors.initials: IR
authors.lastname: Moss
mesh_terms: D000701:Analgesics, Opioid / Q000008:administration & dosage*; D002675:Child, Preschool; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology*; D007223:Infant; D008297:Male; D010149:Postoperative Pain / Q000188:drug therapy*; D012008:Recurrence; D020181:Sleep Apnea, Obstructive / Q000503:physiopathology*
chemical_list: D000701:Analgesics, Opioid