A high incidence of respiratory morbidity after adenotonsillectomy is reported in children with obstructive sleep apnea syndrome (OSAS). In an effort to decrease this morbidity, we implemented perioperative guidelines recommending an adjustment in the administration of opioids, dexamethasone, and atropine in children with OSAS who demonstrated recurrent episodes of profound hypoxemia during the perioperative sleep study. We performed a retrospective review and compared results with historic data from 2001. The primary outcome variable was a major respiratory medical intervention (MMI(Respiratory)). The severity of OSAS was classified with the McGill Oximetry Scoring (MOS) system, and our focus was on those children demonstrating repetitive desaturation <80% (MOS4). The medical records of 292 children who underwent adenotonsillectomy between October 2002 and February 2006 met the inclusion criteria and 97 had been assigned MOS4. Eleven children (11.3%) required an MMI(Respiratory). In 2001, 8 children (29.6%), assigned MOS4, required an MMI(Respiratory). Comparing the new and old guidelines, the adjusted odds ratio for MMI(Respiratory) in MOS4 was 0.30 (95% CI: 0.10-0.85). The key elements achieving this reduction in MMI(Respiratory) were dexamethasone administration and a reduced opioid dosage. In 2002 to 2006, the intraoperative opioid dose, expressed in morphine equivalents, administered to the MOS4 group was 0.10 mg . kg(-1) (0.06-0.12 mg . kg(-1)), and the postoperative morphine dose was 0.02 mg . kg(-1) (0-0.07 mg . kg(-1)). Both doses were lower than the ones administered to the concurrent comparison group, P values <0.001. A change in practice that included a dexamethasone administration and a reduction in opioid administration to children with profound recurrent hypoxia reduced the incidence of MMI(Respiratory) by >50%.