Significance of gastroesophageal refluxate in relation to physical, chemical, and spatiotemporal characteristics in symptomatic intensive care unit neonates.

Gastroesophageal reflux disease (GERD) is a frequent consideration in intensive care unit neonates. We tested the hypothesis that symptoms in GERD are dependent on the spatiotemporal and physicochemical characteristics of reflux events by evaluating the symptom sensitivity index (SSI) and symptom index (SI) in relation to the refluxate characteristics. Thirty symptomatic neonates (30.7 ± 0.8 wk gestation) were evaluated using manometry and pH-impedance methods. During 704.3 h of recordings, 2063 gastroesophageal reflux (GER) were observed; 54% of the GER were associated with symptoms. Defined by physical characteristics, there were 51.3% liquid, 29.1% gas, and 19.6% mixed GER. Defined by chemical characteristics, there were 48.5% acid and 51.5% nonacid GER. Defined by most proximal extent, 79.2% were supra-UES (upper esophageal sphincter) and 20.8% were infra-UES. Higher SSI was noted with pH-only events (p < 0.0001 versus pH-impedance events). Higher SI was noted with movement symptoms (versus sensory, p = 0.04). In a subset analysis, the frequencies of GER events, acid clearance time, and SSI were all greater in chronic lung disease versus none (p < 0.001). In conclusion, clinical significance of symptoms as measured by SSI and SI and characterization of spatial-temporal-physical-chemical nature of GER events as defined by pH-impedance methods clarifies the definition of GERD.