Detection of central and obstructive sleep apnea in children using pulse transit time

The aim of this study was to validate the use of pulse transit time (PTT) as a method to monitor sleep apnea in children. PTT was estimated as the interval between the ECGR-wave and the point at which the pulse wave at the finger reached 50% amplitude. First, we assessed changes in the PTT during breathing against known resistances in 15 awake children; resistance was applied with a modified nose and mouth two-way nonrebreathing face mask, having the inhalation valve port fitted with drilled plastic cylinders of various diameters. Second, we analyzed 20 events of obstructive apnea and 90 events of central apnea during sleep in 10 children. Our data showed good correlation between the inspiratory effort and PTT oscillation amplitude. In addition, PTT oscillation amplitude tuned out to successfully discriminate central from obstructive apnea.