ObjectivesThis study aimed to describe postnatal physiological changes in maximum values of peak electrical activity of the diaphragm (Edi) in extremely preterm infants during the preterm period.Working HypothesisThe amplitude and frequency of neural sigh are different at each postmenstrual age in extremely preterm infants.Study DesignA retrospective, observational study.Patient‐subject selectionEdi values were evaluated in 14 extremely preterm infants with neurally‐adjusted ventilatory assist.MethodologyData of Edi peak and Edi minimum were collected from a ventilator. Edi‐sigh was defined as the Edi peak value that was more than twice as large as the median Edi peak at each postmenstrual week in each patient. The frequency of Edi‐sigh, and median values of Edi‐sigh, Edi peak, and Edi minimum were evaluated at each postmenstrual week. The Jonckheere‐Terpstra test was used to analyze the trend between postmenstrual weeks and Edi values.ResultsFrom 26 to 35 postmenstrual weeks, the number of Edi‐sighs per hour significantly increased as postmenstrual weeks increased (P < .001). Furthermore, the median values of Edi‐sigh significantly increased as postmenstrual weeks increased (16.9 µV at 26 weeks to 25.4 µV at 35 weeks, P < .001). There were no significant changes in the median values of Edi peak and Edi minimum at each week.ConclusionsThe amplitude and frequency of neural sigh in extremely preterm infants increase with the number of postmenstrual weeks.

No abstract