Esophageal pH Monitoring/Multiple Intraluminal Esophageal Impedance (MII)

Esophageal pH monitoring measures the frequency and duration of acid reflux events in the esophagus. The total percentage of time that the esophagus is exposed to gastric acid is called the reflux index, and this is the most commonly used measure when evaluating patients with pH-metry. “Normal” ranges for pediatric patients have been established; however, there is a continuum between physiologic GER and GERD, and the reproducibility of pH monitoring is variable. Therefore, the normal ranges should simply be used as rough guidelines rather than absolutes, and the study must be interpreted by someone experienced in reading ph-metry studies.

Impedance monitoring is similar to pH-metry, but this technology is able to measure nonacidic reflux events. Normal ranges for all age groups are still being established.

pH-metry and impedance monitoring can also be used to evaluate for a causal relationship between a particular symptom and a reflux event. For more information, see 2009 NASPGHAN Guidelines, paragraph 4.2, Esophageal pH Monitoring and paragraph 4.3, Combined Multiple Intraluminal Impedance and pH Monitoring.