Gastroesophageal reflux disease (GERD) has long been thought to be determined by the amount of stomach acid refluxing into the esophagus – so it is often treated with acid-suppressive medications.
However, a new study from the Neonatal and Infant Feeding Disorders Program at Nationwide Children’s Hospital shows that stomach acid alone doesn’t appear to have much to do with GERD at all, and responses to esophageal stimulation are more important.
“We would expect that if the amount of acid was high, there would be more GERD, but that didn’t matter,” says Sudarshan Jadcherla, MD, associate chief of Neonatology at Nationwide Children’s, principal investigator in the hospital’s Center for Perinatal Research and senior author of the study. “Symptom prevalence did not differ with severity of the acid reflux index, or ARI, which is the amount of acid over 24 hours.”
Dr. Jadcherla and colleagues designed the study to determine why symptoms occur in preterm infants thought to have GERD.
In addition to measuring acid, the investigators measured the impact of different types and volumes of stimuli in the mid-esophagus on peristaltic reflexes and symptom generation in 74 preterm infants showing signs of GERD. They found that peristaltic responses and physical, cardiorespiratory and sensory symptoms increased with incremental stimulus volumes, no matter the type of stimulus.
Overall, peristalsis, or the muscle contractions that push food down the esophagus to the stomach, occurred after 71 percent of stimuli and symptoms occurred after 17 percent.
“All these findings show that GERD should not be diagnosed and severity should not be assigned based on symptoms alone,” says Dr. Jadcherla, who is also a professor of pediatrics at The Ohio State University College of Medicine.
The study is published in The Journal of Pediatrics.
Gastroesophageal reflux (GER) is common and happens when the lower sphincter in an infant’s esophagus is underdeveloped and lets stomach contents back up into the esophagus, according to the National Institutes of Health. GERD happens when the sphincter is weak or relaxes when it should be closed and lets stomach contents back up in the esophagus.
For this research, the team determined the ARI by using a pH meter to measure acidity and a pH impedance study to measure the volume of liquid moving in the esophagus and stomach.
Because GERD symptoms occur largely at unpredictable times, the team stimulated the esophagus of each infant with increasing volumes of air, water and apple juice. Stimulations totaled 2,635 for the group. Investigators used manometry to monitor peristalsis and recorded symptoms such as arching, gasping, coughing, grunting, decreased heart rate and decreased oxygen saturation in the blood.
As stimulation volume increased, symptoms and peristalsis increased. Analyses indicated that symptoms and peristalsis are the result of neurosensory and neuromotor activation but that ARI severity had no role in symptom generation.
Based solely on symptoms, all infants in the study could have received treatment, Dr. Jadcherla says.
“Symptoms can be generated with even trivial stimuli, and not all are troublesome,” Dr. Jadcherla says. If an infant is feeding but has persistent, troublesome symptoms, “get a good clinical evaluation to understand the mechanisms behind the symptoms before labeling the child as having GERD, and putting someone on GERD therapies. Specialty testing may sometimes be needed for diagnostic accuracy in complex infants, as the consequences of non-evidence based therapies can be considerable amidst uncertain diagnosis.”
Collins CR, Hasenstab KA, Nawaz S, Jadcherla SR. Mechanisms of aerodigestive symptoms in infants with varying acid reflux index determined by esophageal manometry. The Journal of Pediatrics. 2019 Mar; 206:240-247.