The frequency of apneas in very preterm infants is increased after non-acid gastro-esophageal reflux

Background To evaluate whether physical and/or chemical features of gastro-esophageal reflux (GER) influence its relationship with apnea of prematurity (AOP). Methods Fifty-eight preterm newborns (GA < 33 weeks) with recurrent apneas were studied by simultaneous polysomnography and combined impedance and pH monitoring, to analyze whether the correlation between GER and AOP varies according to the acidity, duration and height of GERs. Key Results The frequency of apnea (number apnea/min) occurring after-GER [median (range) 0.07 (0-0.25)] was higher than the one detected in GER-free period [0.06 (0.04-0.13), P = 0.015], and also than the one detected before-GER [0 (0-0.8), P = 0.000]. The frequency of apneas detected in the 30'' after pH-GER [median (range), 0 min-1 (0-1.09)] was higher than the frequency detected in the 30'' before [0 (0-0.91), P = 0.04]; even more, the frequency of apneas detected after non-acid MII-GER episodes [0 (0-2)] was significantly higher than the one detected before [0 (0-1), P = 0.000], whereas the frequency of apneas detected before acid MII-GER episodes [0 (0-0.67)] did not differ from the one detected after [0 (0-2), P = 0.137]. The frequency of pathological apneas detected in the 30'' after-GER (0 min-1, range 0-0.55) was higher than the frequency detected before (0, range 0-0.09; P = 0.001). No difference in mean height or in mean duration was found between GERs correlated and those non-correlated to apnea. Conclusions & Inferences Non-acid GER is responsible for a variable amount of AOP detected after-GER: this novel finding must be taken into consideration when a therapeutic strategy for this common problem is planned.