Apnea duration is related to ventilatory oscillation characteristics in newborn infants

The occasional short apneas seen in full-term infants within the first postnatal week are related to the minimum phase of oscillatory breathing patterns. To determine the relationship between breathing patterns and the longer and more frequent apneas seen in premature infants, we monitored respiration in 14 premature infants using a face mask and pneumotachograph. Tidal volume, breath duration, and ventilation were calculated on a breath by breath basis, converted to time-axis data strings, and filtered with a comb of zero phase shift digital band pass filters to detect breathing patterns. Compared with full-term infants, premature infants had breathing patterns that occurred more often and had twice the average amplitude. Of 182 apneas ≥ 3 s long, 94% occurred at the minimum phase of oscillatory breathing patterns. All of the 38 apneas ≥ 10 s long occurred at the minimum phase of oscillatory breathing patterns. Duration of apnea was related to breathing pattern characteristics, e.g., longer apneas were related to stronger, longer cycle-time breathing patterns. Apnea in the premature infant is not an isolated event but is one aspect of an underlying pattern.