Frequency of gastroesophageal reflux in neonates as assessed by 24-hour pH monitoring.

The purpose of the present study was to determine the frequency and the other characteristics of gastroesophageal reflux (GER) in 46 asymptomatic neonates during the first weeks of life. The GER were assessed by 24-hour continuous esophageal pH monitoring (CPR). The frequency of all the GER was 0.66 +/- 0.54/h (0 to 2.21). Half of the GER were determined as acid (pH less than 4 during at least 15 sec), 23% as highly acid (pH less than 3 during at least 15 sec), 39% as weakly acid (abrupt fall of the pH higher than 1 unit pH), and 11% as non acid (abrupt increase of pH higher than 1 unit pH). According to these results, a CPR should be considered as pathologic in neonates when the following criteria are fulfilled (upper limits fixed at means + 2 S.D.): 1. frequency of acid GER longer than 5 min above 0.35/h; 2. time ratio at pH below 4 exceeding 10.4%; or 3. frequency of very acid GER greater than 0.53/h.