Potential usefulness of noninvasive autonomic monitoring in recognition of arousals in normal healthy children.

INTRODUCTION Current methods employed for scoring arousals in children may not be sensitive enough. Because arousals are associated with increases in sympathetic tone, measurement of sympathetic activity using noninvasive techniques could provide useful surrogate markers for arousals in children. METHODS Ten healthy children underwent overnight polysomnographic assessment with simultaneous pulse transit time (PTT) and peripheral arterial tonometry (PAT) measurements. Arousals (electroencephalogram and/or movement) and PTT and PAT events were identified independently, with scorers blinded to the other signals. RESULTS A total of 1985 events were identified in 10 records. Of these, 657 were electroencephalographic arousals, of which 548 (83%) were identified by either PTT and/or PAT. The sensitivity and specificity of PTT for recognizing arousals were 0.74 and 0.25, respectively, whereas the sensitivity and specificity of PAT for recognizing arousals were 0.57 and 0.13, respectively. Because movement arousals result in brief periods of artifact on the PTT and PAT signals, we reanalyzed the PTT and PAT events to include artifact events. Reanalysis increased the sensitivity of PTT for recognizing arousals to 0.96 and that of the PAT to 0.92 and increased PTT and PAT specificity to 0.30 and 0.19, respectively. CONCLUSION Both PTT and PAT events are extremely sensitive techniques for arousal recognition in children. Furthermore, a substantial proportion of autonomic events occur in children without any accompanying visually recognizable electroencephalographic changes, suggesting that PTT and PAT may provide useful alternatives for arousal recognition during ambulatory sleep monitoring in children.