Characterization of the acute pulse transit time response to obstructive apneas and hypopneas in preschool children with sleep-disordered breathing.

Background: Surges in heart rate (HR) and blood pressure (BP) at apnea termination contribute to the hypertension seen in obstructive sleep apnea (OSA). Because childhood OSA prevalence peaks in the preschool years, we aimed to characterize the cardiovascular response to obstructive events in preschool-aged children.

Methods: Clinically referred children aged 3-5 years were grouped by obstructive apnea-hypopnea index (OAHI) into the following: primary snoring (PS) (OAHI≤1 event/h [n=21]), mild OSA (OAHI>1-≤5 [n=32]), and moderate to severe (MS) OSA (OAHI>5 [n=28]). Beat-to-beat pulse transit time (PTT), an inverse continuous indicator of BP changes, and HR were averaged during the two halves (early and late) and during the peak after (post) each obstructive event and were expressed as percentage change from late- to post-event.

Results: We analyzed 422 events consisting of 55 apneas and 367 hypopneas. A significant post-event increase in HR and fall in PTT occurred in all severity groups (P<.05 for all). A greater response was associated with OSA, nonrapid eye movement sleep (NREM), cortical arousal, hypopneas, and oxygen desaturation (P<.05 for all).

Conclusions: Obstructive events elicit acute cardiovascular changes in preschool children. Such circulatory perturbations have been implicated in the development of hypertension, and our findings complement previous studies to suggest a cumulative impact of snoring on the cardiovascular system from childhood into adulthood.