Fig. 3.

Physiological time series during apnea events. (a) Heart rate, EKG, impedance pneumography, peripheral oxygen saturation (SpO₂), and apnea probability for three minutes from a preterm infant. There is a cluster of three clinically significant apnea events within three minutes. (b) Time series of apnea events for a preterm infant over a two week period, from 33 to 35 weeks post-menstrual age. Each band represents the number of apnea events longer than 10 seconds in one half-hour; increasing density indicates more apnea. (c) Heart rate, EKG, impedance pneumography, peripheral oxygen saturation (SpO₂), and apnea probability for three minutes from a preterm infant. A prolonged period of apnea with associated bradycardia and oxygen desaturation lasting nearly two minutes is apparent. Isolated breaths during this episode may allow the prolongation.