Cardiac and respiratory reactivity to gastroesophageal reflux: experimental data in infants

Gastroesophageal reflux associated with apnea and/or bradycardia induces both dilatation of the esophagus and abrupt intrusion of acid content in it. To evaluate the relative importance of these two types of stimulation on cardiac and respiratory responses, a series of experimental protocols were designed, in which we evaluated the influence of esophageal dilatation alone, acid infusion alone and both stimulations simultaneously. The passage of a volume in the lower third of the esophagus (n = 14) during reflux was simulated by balloon dilation; the passage of acid gastric juice during reflux was simulated by an esophageal acid infusion test, within the physiological range (n = 8; duration = 5 min; pH = 2.2). Cardiac, respiratory and arousal responses were compared during a control period and during the distal balloon dilatation and esophageal saline and acid infusion periods. Distal esophageal balloon dilatation and acid infusion induced significant prolongation of the RR interval and of the duration of the respiratory cycle. The presence of the esophageal catheter did not lead to continuous vagal stimulation. Simultaneous stimulation by balloon dilatation and acid infusion provoked cardiac responses that were above the level reached by each stimulation separately. Behavioral and electroencephalographic observations demonstrate significantly more frequent and longer arousal responses during the acid infusion than during control and saline infusion periods. We conclude that distal esophageal balloon dilatation and acid infusion elicit significant cardiac and respiratory responses in newborns during active sleep.(ABSTRACT TRUNCATED AT 250 WORDS)