Respiratory cortical processing to inspiratory resistances during wakefulness in children with the obstructive sleep apnea syndrome.

Children with the obstructive sleep apnea syndrome (OSAS) have impaired respiratory afferent cortical processing during sleep that persists after treatment of OSAS. However, it is unknown whether this impairment is present during wakefulness and, if so, whether it improves after OSAS treatment. We hypothesized that children with OSAS, during wakefulness, have abnormal cortical processing of respiratory stimuli manifested by blunted respiratory-related evoked potentials (RREP) and that this resolves after OSAS treatment. We measured RREP during wakefulness in 26 controls and 21 children with OSAS before and after treatment. Thirteen participants with OSAS repeated testing 3-6 mo after adenotonsillectomy. RREP were elicited by interruption of inspiration by total occlusion and 30 and 20 cmH2O/l per s resistances. Nf at Fz latency elicited by occlusion was longer in children with OSAS at baseline compared with controls (78.8 ± 24.8 vs. 63.9 ± 19.7 ms, P = 0.05). All other peak amplitudes and latencies were similar between the two groups. After OSAS treatment, Nf at Fz latency elicited by 30 cmH2O/l per s decreased significantly (before, 88 ± 26 vs. after, 71 ± 25 ms, P = 0.02), as did that elicited by 20 cmH2O/l per s (85 ± 27 vs. 72 ± 24 ms, P = 0.004). The amplitude of N1 at Cz elicited by occlusion increased from -3.4 ± 5.6 to -7.4 ± 3 μV (P = 0.049) after treatment. We concluded that children with OSAS have partial delay of respiratory afferent cortical processing during wakefulness that improves after treatment.