Evaluation of infantile acid and nonacid gastroesophageal reflux using combined pH monitoring and impedance measurement

Objective: Characterize the proportion of acid and nonacid esophageal reflux events in young infants with suspected gastroesophageal reflux (GER) using combined pH-multichannel intraluminal impedance (MII) monitoring. Determine the symptom index correlation with nonacid reflux and acid reflux events. Study Design: Prospective study of children, aged 2 weeks to 1 year, referred to The Children's Hospital of Denver Gastroenterology Clime for evaluation of GER. Exclusion criteria were congenital anomalies or syndromes, cerebral palsy, mental retardation, and pulmonary or cardiac disease. The children were admitted to The Children's Hospital General Clinical Research Center for a 20 hour pH-MII study. Acid suppression was either never used or discontinued 2 weeks before testing. Results: Thirty-four infants were enrolled from February 2004 to February 2005. Ages ranged from 2 months to 11 months, median = 7 (20 females/14 males). One thousand eight hundred ninety reflux events were detected by MII, and 588 reflux events were detected by pH probe alone. The percent of reflux that was acid was 47% (888 events) versus 53% of (1,002 events) nonacid reflux events. The proportion of nonacid reflux decreased with age (P < 0.0001 by Pearson chi(2) test) and with increasing time elapsed from last meal. There were 958 total symptoms evaluated. The most frequently reported symptom was fussiness/pain, which correlated with nonacid reflux events 24.6% and acid reflux 25.2%. The proximal height of a reflux was predictive for symptoms of fussiness/pain, arching, and burping. Conclusion: MII detects more reflux events than pH monitoring alone. The proportion of nonacid reflux to acid reflux events in infants is more similar to adults than previously reported. Combined pH-MII esophageal monitoring identifies more reflux events and improves clinical correlation with symptoms.