Characterization of neural breathing pattern in spontaneously breathing preterm infants.

The aim was to characterize the neural breathing pattern in nonintubated preterm infants. The diaphragm electrical activity (EAdi) and heart rate were simultaneously measured repeatedly for 1 h over several days using a modified feeding tube equipped with miniaturized sensors. The EAdi waveform was quantified for phasic and tonic activity, neural timings, and prevalence of recurring patterns, including central apnea. Ten infants with mean age 7 d (range, 3-13 d) were studied. Their birth weight was 1512 g (1158-1800 g) and GA at birth 31 wk (28-36 wk). Neural inspiratory and expiratory times were 278 ms (195-450 ms) and 867 ms (668-1436 ms) and correlated with GA (p < 0.001). Tonic EAdi represented 29.5% of phasic EAdi (16-40%) and was related to GA (r = 0.61, p < 0.001). For the group, 68% of the time was regular phasic breathing (without tonic activity) and 29% of the time with elevated tonic activity. Central apneas >5 s occurred on average 10 times per hour (2-29). Heart rate reductions were correlated to central apnea duration. In conclusion, esophageal recordings of the EAdi waveform demonstrate that neural breathing pattern is variable, with regards to timing, amplitude, and pattern with a distinct amount of tonic diaphragm activity.