Severe hypoxemia in children with upper airway obstruction during sleep does not lead to significant changes in heart rate.

Life-threatening cardiac arrhythmias, including bradyarrhythmias, are well-known sequelae of obstructive sleep apnea syndrome (OSAS) in adults and are associated with apnea and severe hypoxemia. Since the clinical expression of OSAS in children is different, we questioned whether arrhythmias are a common feature of pediatric OSAS. Therefore, we analyzed R-R interval patterns from 12 subjects (age 8 months to 14 years) with OSAS in detail. The diagnosis of pediatric OSAS is based on clinical signs of loud snoring and paradoxical respiratory efforts, as well as elevated end-tidal carbon dioxide tension (PETCO2) and major phasic decreases of oxyhemoglobin saturation (SaO2). Two hundred and nine episodes of severe hypoxemia, defined as SaO2 values < or = 85% lasting > or = 30 seconds, were identified. Only 29 (14%) of these episodes were associated with obstructive apneas. The R-R intervals were analyzed before and during each desaturation. Compared to baseline, mean and minimum R-R intervals (RRmean, RRmin) decreased during the desaturation episodes (P < 0.05), while maximum R-R interval (RRmax) increased (P < 0.05). Although the absolute changes in all parameters were significantly different from baseline, the magnitude of these changes was small, with a mean of -5.3%, -12.2%, and 10.4% for RRmean, RRmin, and RRmax, respectively. No child had life-threatening arrhythmias. Although severe hypoxemia existed in these children, the magnitude of the R-R interval changes was modest, and profound bradycardia as described in adults, was rare.(ABSTRACT TRUNCATED AT 250 WORDS)