OBJECTIVETo evaluate the clinical application of 24-hour esophageal multichannel intraluminal impedance-pH monitoring technique in preterm infants.

METHODThis study enrolled 28 preterm (male 20, female 8) infants with symptoms suggestive of gastroesophageal reflux (GER) (frequent regurgitations, apnea, or transcutaneous oxygen saturation decreased). They had postmenstrual age from 26 to 32 weeks, median (28.9 ± 1.9)weeks, had birth weight from 850 to 1 700 g, median (1 250.4 ± 272.8)g, range 850-1700 g, and were studied at corrected gestational age from 28 to 40 weeks, median (34.5 ± 2.3)weeks. Combined measurement of esophageal pH and impedance was performed. The 24-hour pH-impedance recording was uploaded onto a portable storage card and for computer-assisted manual analysis, using a specialized software program. When values were distributed normally, they were presented as mean and standard deviation, compared using t test. When values were not distributed normally, they were presented as median, minimum and maximum. Median values were compared using the Mann-Whitney U non-parametric test. SPSS 17.0 software was used.

RESULTIn 28 preterm infants, 71.4% (20/28) had pathological acid refluxes with pH monitor, while 100% with combined measurement of esophageal pH and impedance. Gestational age, birth weight, corrected gestational age had no association with acid GER. Frequent regurgitations, apnea, or transcutaneous oxygen saturation decreased but there was no statistically significant difference between acid GER group and non-acid GER group. Eight cases had no pathological acid refluxes, but showed an increase of weakly acid refluxes than pathological acid refluxes group (P < 0.01) . The median number of reflux events in 24 hours for 28 cases was 64.5 (0-377) , 23.4% were acidic, while 76.4% were weakly acidic; 59.1% were liquid bolus refluxes, while 40.9% were mixed bolus refluxes. The positive ratio of symptoms related index and symptoms association probability were significantly increased combined measurement of esophageal pH and impedance versus pH monitor were used.

CONCLUSIONThe 24-hour esophageal impedance-pH monitoring technique was safe and had good tolerance. We confirmed that it detected more weakly acidic refluxes, liquid bolus refluxes, and mixed bolus refluxes. And it provided more evidence for explaining the relationship between GER and clinical manifestation.