Esophageal pH measurements in newborn infants. Value and indications

Esophageal pH monitoring is now the most reliable test in the diagnosis of gastroesophageal reflux (GER) in infants and children. A 18-24 hr esophageal pH monitoring is undertaken in 26 newborns to validate this test for this age group where GER is frequent with fair correlation of clinical presentation. In 19 infants with suspicion of GER, this test give a positive diagnosis in 12 of them. Seven out of these 12 infants have another investigations (barium- esophagram - scintigraphy - esophagoscopy) with only a positive diagnosis of GER in 4 cases. Esophageal pH monitoring in 7 control infants show that the percent of monitoring time with pH below 4.0 is one of the best discriminative values (upper limit: 4.2%) for the diagnosis of GER. Unusual symptoms of GER in the neonatal period as apneic spells, dyspnea, cyanosis or neurological signs are indications for esophageal pH monitoring.     

Gastroesophageal reflux disease in infants: how much is predictable with questionnaires, pH-metry, endoscopy and histology?

Symptoms of gastroesophageal reflux disease (GERD) are common in infants. It is often difficult to discriminate between physiological and pathologic gastroesophageal reflux, although this discrimination is essential to determine which infants to evaluate and treat. OBJECTIVES: To identify the prevalence of reflux symptoms in infants and to evaluate the predictive value of a questionnaire and the correlation between pH study, histology and clinical score. METHODS: Parents of 100 unselected infants visiting the well-baby clinic and 100 infants suspected of having gastroesophageal reflux disease were asked to fill in a 35-item questionnaire. A validated score, the Orenstein I-GERQ, was applied for selected questions. All infants suspected of having gastroesophageal reflux disease underwent prolonged esophageal pH monitoring and 44 or 100 underwent upper gastrointestinal tract endoscopy with esophageal biopsy. RESULTS: Parents of infants with suspected gastroesophageal reflux disease reported significantly more regurgitation (68% versus 45%, P < 0.05) and crying (51% versus 20%, P < 0.01) compared with the parents of healthy infants. A pathologic pH study (reflux index > 10%) was found in 21 of 100 (21%) infants and was significantly associated only with pneumonia, apnea with fussing (P = 0.013 for both), defecation less than once a day (P = 0.033) and constipation (P = 0.05). Esophagitis was present in 17 of 44 (39%) and no one question was found to be significantly predictive. 38% of infants with a pathologic pH study had a normal esophageal biopsy and 53% of infants with histologic esophagitis had a normal pH study. Discordance between pH study and biopsies occurred in 14 of 44 (32%) patients. The Orenstein I-GERQ cut-off score failed to identify eight of 31 (26%) infants with gastroesophageal reflux disease. Conversely, the score was positive in 17 of 22 (81%) infants with normal biopsy and pH study and in 14 of 47 (30%) infants with normal pH study. CONCLUSIONS: Clinical symptoms, histology and pH study show poor correlation in infants. Clinical symptoms such as regurgitation and crying are less frequent in unselected infants than in infants suspected of gastroesophageal reflux disease. However, questionnaires are poorly predictive for the severity of gastroesophageal reflux disease, as they do not correlate with esophageal acid exposure as measured by pH-metry and with esophagitis as evaluated by histology of esophageal biopsies.     

Does simultaneous gastric and esophageal pH monitoring increase the diagnosis of gastroesophageal reflux disease?

The duration of gastric acidity may affect the interpretation of esophageal pH monitoring study. The aim of this study was to increase the sensitivity of pH monitoring by simultaneous gastric and esophageal pH recording. Fifty-seven patients were enrolled in the study. After the first analysis, the recording periods in which gastric pH was >4 were excluded and after this exclusion parameters were recalculated. Of the 57 patients, 14 (24.6%) (mean age, 70+/-4.6 years) were diagnosed as having gastroesophageal reflux disease with the use of conventional method. After correction, gastroesophageal reflux disease diagnosis was made in 6 additional patients (mean age, 2.4+/-2.4 years) and total number of patients with reflux increased to 20 (35.1%) (p=0.031). The mean percentage time of gastric pH>4 was significantly greater in children younger than 2 years of age than that in those older than 2 years of age (50.6%+/-15.2% vs 33.7%+/-18.1%) (p=0.001). Exclusion of periods in which gastric pH>4 affected the results more obviously in patients younger than 2 years. Simultaneous gastric and esophageal pH monitoring is useful for the diagnosis of gastroesophageal reflux disease, particularly in children younger than 2 years of age.     

Acid gastroesophageal reflux in the child with intubation, artificial respiration and continuous nutrition. Apropos of 28 cases

Continuous monitoring of distal oesophageal pH and oesophagoscopy were performed in 28 children aged 15 days to 12 years (mean: 14 months) intubated and ventilated for bronchiolitis (7), pneumonia (8), epiglotitis (2), neurological distress (8), whooping cough (2) or recurrent apneic spells (1). Esophageal pH was studied 2-8 days (mean: 2 days) after intubation; its duration was 12-23 h 50 min (M: 22 h). An abnormal gastroesophageal reflux was presumed when the percent of total monitoring time during which the esophageal pH fell below 4.0 was above 5.2%. The esophagoscopy was carried out on the day following the pH monitoring. All children were in the supine position and fed a pH 7 diet infused continuously with a nasogastric tube; 15 children were under pancuronium. An abnormal gastroesophageal reflux was found in 4 children, associated with a benign esophagitis in 2. A benign esophagitis without gastroesophageal reflux was found in 3 cases. One child had a peptic ulcer of the bulb without gastroesophageal reflux nor oesophagitis. 21 children had no abnormality. Only one of the 15 children under pancuronium had an abnormal gastroesophageal reflux. We conclude that in intubated children fed continuously with a nasogastric tube, gastroesophageal reflux is unfrequent and, when present, appears to have little consequences.     

Bile in the esophagus: a factor in the pathogenesis of reflux esophagitis in children

OBJECTIVES: Bile reflux has been postulated to be an important factor contributing to gastroesophageal reflux disease in adults. The purpose of this study was to investigate its role in children. METHODS: Sixty-five children with symptoms of gastroesophageal reflux disease were classified on the basis of the endoscopic grade of reflux esophagitis: no esophagitis (n = 26), mild to moderate esophagitis (n = 26), and severe esophagitis (n = 13). Simultaneous 24-hour esophageal pH and bilirubin monitoring with Bilitec 2000 was performed. RESULTS: Both bile and acid reflux increased with the severity of esophagitis. The differences between all groups were significant for the percentage of total (P < 0.0005), upright (P < 0.05), and supine time (P < 0.0005) bilirubin absorbance > or = 0.14, as well as for the percentage of total and supine time pH < 4, and DeMeester score (P < 0.0005). Combined pathologic acid and bile reflux was found in 11% of children with mild esophagitis and in 70% of children with severe esophagitis, while isolated bile reflux was found in 31% and 7.5%, respectively. Combined pH and bilirubin monitoring, compared with ph-monitoring alone, increased the sensitivity from 56% to 79%, and the accuracy from 69% to 83%. CONCLUSIONS: Both bile and acid reflux increase stepwise with the severity of esophagitis. Combined acid and bile reflux is associated with severe esophagitis. Isolated acid or bile reflux is usually present in mild esophagitis. Simultaneous esophageal pH and bilirubin monitoring has a higher sensitivity, as well as predictive values and accuracy than ph monitoring alone.     

胃食管反流动物模型及其病理生理演变的研究

目的 研究新生哺乳动物造成胃食管反流的各种因素及其演变。方法 采用新生猪仔,制成破坏食管下端、食管裂孔防反流机制、胃壁部分浆肌层切除及幽门十二指肠不全梗阻等4组模型。与对照组统一喂养,并采用钡餐透视、胃食管测压、pH值监测及胃肠激素的检测,系统观察各实验猪仔发生反流及转归的病理演变。结果 证实胃食管反流是综合因素所造成胃蠕动缓慢、排空障碍是造成反流的主要因素。结论 胃食管的防反流机制是综合协调完成怕,其中幽门十二指肠协调运动与食管清除蠕动起主要作用。     

Xanthines in apnea of premature infants. Influence on gastroesophageal reflux

Theophylline and caffeine are two xanthine-derivated drugs frequently administered for their stimulating effects on the respiratory center in premature babies presenting with "idiopathic apnea". These drugs are known to increase the gastric acid secretion and to decrease the lower esophageal sphincter pressure, that in turn possibly increase gastroesophageal reflux. We studied 14 premature babies presenting with "idiopathic apnea", treated with caffeine at recommended dose (2.5 mg/kg/day). At 24 hour continuous esophageal pH monitoring was performed 3 to 5 days after starting the treatment. In 6 babies total reflux time (5.6% of the investigation time with ph less than 4) and the number of refluxes in 24 hours (15.3) were significantly increased compared to the other 8 babies (pH less than 4: 0.92%; number of refluxes 6.1). These results were also compared to the results obtained ina symptomatic full term neonates (5-10 days old) (pH less than 4: 0.87; number 5.3/24 hours). The results we obtained in the caffeine treated group were independent of the plasma xanthine levels (all within or below therapeutic ranges). A second pH monitoring 2 weeks after stopping caffeine administration was always within normal ranges. The increase of gastroesophageal reflux seems individual for each patient. Gastroesophageal reflux can lead to pulmonary aspiration, and, in this way, it can be the origin of obstructive apnea or aspiration pneumonia.     

Gastroesophageal reflux associated with respiratory abnormalities during sleep

To determine whether gastroesophageal reflux (GER) might be a factor in the pathogenesis of apnea in certain infants, we analyzed the frequency of prolonged central apnea (greater than 15 s) and of numerous irregularly repeated short apneas (5-15 s) ("respiratory dysfunction") in infants with an apparent life-threatening event (ALTE) (group 1, n = 62), in control infants (group 2, n = 387), and in infants with GER pathologic findings (group 3, n = 60). Finally, the incidence of GER was analyzed in 76 infants with a respiratory dysfunction during sleep (group 4). Gastroesophageal reflux was investigated using 24-h esophageal pH monitoring; respiration during sleep was investigated by polysomnography. The pH monitoring data and results of sleep investigation were analyzed in a double-blind study. A great number of infants who had an ALTE appeared to suffer from GER (42%, 26 of 62 infants), especially if the ALTE occurred while the infant was awake (52%, 14 of 27 infants). In the control infants, pH monitoring data were abnormal in 8.5%; respiratory dysfunction was observed in 5%. In those with a respiratory dysfunction, GER was detected in 75% (15 of 20 infants). In those with GER, respiratory dysfunction was observed in 45% (15 of 33 infants). In groups 3 and 4, respiratory dysfunction was associated with abnormal pH data in 40-43%. If, in the infants with a respiratory dysfunction, the GER pathologic symptoms were treated efficiently (normalization of pH data), respiratory dysfunction disappeared in 92%.(ABSTRACT TRUNCATED AT 250 WORDS)     

Gastroesophageal reflux with drifting onset in infants: a phenomenon unique to sleep.

We have characterized the gastroesophageal reflux (GER) episodes which occurred during sleep in 28 infants with pathologic gastroesophageal reflux and 10 symptomatic age-matched controls without gastroesophageal reflux. We describe three kinds of episodes during the sleeping period-awake episodes which occur completely during electroencephalogram (EEG)-defined wakefulness associated with clinical evidence of the waking state (62 episodes), episodes occurring during EEG-defined sleep which have a rapid drop in pH at their onset (119 episodes), and episodes occurring during EEG-defined sleep in which the esophageal pH drifts down slowly over a period up to 30 min (113 episodes). Only 9 of the 10 control subjects experienced any reflux episodes during monitoring. The total number of episodes of reflux in controls (34) was less than the total number in reflux subjects (260). Controls did, however, experience all three types of reflux episode. Awake episodes all had a rapid drop in pH at their onset and were characterized by a short acid clearance time (2.0 +/- 0.3 min in reflux patients and 1.0 +/- 0.2 min in controls). The sleep episodes with rapid onset had longer mean acid clearance time than the awake episodes, significantly so in GER subjects (20.1 +/- 6.8 min in reflux subjects and 2.6 + 1.3 min in controls). Body movement was noted at the onset of 93.4% of rapid-onset sleep episodes in reflux subjects and 88.9% in controls. Body movement was also common at the termination of rapid-onset sleep episodes (77.8% of rapid-onset episodes in reflux subjects and 80.0% in controls).(ABSTRACT TRUNCATED AT 250 WORDS)     

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.     

Lack of efficacy of thickened feeding as treatment for gastroesophageal reflux

The efficacy of thickened feedings for the treatment of gastroesophageal reflux in infancy was evaluated. Fifty-two infants were examined with prolonged pH monitoring of the distal esophagus after feedings of apple juice or apple juice thickened with rice cereal. All infants had a minimum of three feedings of both thickened and unthickened juice. The recordings of distal esophageal pH were analyzed for the percent of time the pH was less than 4 in the first 2 hours after each feeding. The infants were maintained in the following positions after feeding: prone (n = 29), prone-board with the head elevated 30 degrees from horizontal (n = 29), supine (n = 7), and unrestricted (n = 21). We found no significant difference in the percent of time with reflux with thickened versus unthickened feedings except in those infants maintained in the 30-degree prone position. In the first 2 hours after eating thickened juice, infants maintained in this position had increased esophageal reflux time (P less than 0.006). Further analysis revealed that 33% of the infants had a greater than 30% increase in esophageal reflux time after thickened feedings. Our study suggests that the immediate effect of thickened feedings on gastroesophageal reflux in infants is unpredictable.     

奥美拉唑和多潘立酮联合治疗小儿胃食管反流病的临床观察

目的 评价质子泵抑制剂奥美拉唑和胃肠动力药多潘立酮联合治疗小儿胃食管反流病的效果.方法 对76例反流性食管病患儿在应用奥美拉唑和多潘立酮联合治疗前后的临床表现、24 h食管pH监测值、电子胃镜检查及内镜下黏膜活检的变化情况及不良反应进行比较.结果 76例患儿用药前及用药后每2周进行临床症状观察,发现治疗后临床症状逐渐改善及消失,24 h食管pH监测各项指标在治疗后均小于治疗前,差异有统计学意义(P＜0.01);治疗前后电子胃镜检查及活检发现,治疗后患儿反流性食管炎表现逐渐好转或消失,差异有统计学意义(P＜0.01),治疗后未见明显不良反应.结论 奥美拉唑联合多潘立酮治疗小儿胃食管反流疗效确切,无不良反应.     

Effects of maturation and gastric acidity on gastroesophageal reflux in infants

Using prolonged esophageal pH monitoring, we examined 42 infants referred for gastroesophageal reflux (GER) over a 16-month interval. Eighteen of these infants were also examined with intragastric pH monitoring following a standard formula meal. We found that prematurity and postcibal gastric acidity were significantly correlated with the amount of GER observed. Historical symptoms appeared to have little correlation with the amount of GER as measured by prolonged intraesophageal pH monitoring.     

Normal ranges of continuous pH monitoring in the proximal esophagus

BACKGROUND: To determine normal ranges of gastroesophageal reflux (GER) in the proximal esophagus, measured with continuous pH monitoring. Normal ranges in the distal esophagus have been published. Because esophageal pH monitoring is frequently performed in children with atypical manifestations such as chronic respiratory disease, and because one of the possible pathophysiologic mechanisms may be (micro-)aspiration, it may be relevant to establish normal ranges in the proximal esophagus. METHODS: Twenty-four-hour pH monitoring was performed in 200 children with suspected GER disease. The mean age of the patients was 4.5 months (range, 0.5-17.0 months). After initial analysis, patients were divided into three groups according to the reflux index (RI) in the distal esophagus, because it could be speculated that the amount of reflux reaching the proximal esophagus depends on the amount of reflux in the distal esophagus: Group I (n: 120) children had a distal RI of less than 5% and were considered normal, group II (n:50) had a distal RI of 5% to 10% and was considered to have intermediate disease, and group III (n:30) had a distal RI of more than 10% and was regarded as pathologic. The following parameters are calculated: the RI, the total number of reflux episodes, the number of reflux episodes lasting more than 5 minutes, the duration of the longest reflux episode, and the acid clearance time (ACT). RESULTS: The median RI in the distal esophagus was 3.8 +/- 0.34 (standard error of the mean [SEM]), and in the proximal esophagus, the RI was 1.2 +/- 0.23. In group I patients, the RI in the proximal esophagus was 0.5% +/- 0.09%, in group II the RI increased significantly to 2.75% +/- 0.34% (P [group I compared with group II] < 0.01), and in group III the RI was 6.15% +/- 0.96% (P [II-III] < 0.01). The number of acid reflux episodes in group I was 17.0 +/- 2.27, in group II the number increased to 62.5 +/- 8.18 (P [I-II] < 0.01), and in group III it reached 102.0 +/- 23.9 (P [II-III] < 0.05). Also the duration of the longest reflux episodes and the number of reflux episodes lasting more than 5 minutes increased from group I to group II, and from group II to group III. The ACT was shorter in the proximal esophagus (group I 0.3 +/- 0.06 minutes; group II 0.48 +/- 0.07 minutes, P [I-II] = not significant [NS]; group III 0.56 +/- 0.17 minutes P [II-III] = NS) than in the distal esophagus (group I 0.49 +/- 0.03 minutes, P [proximal ACT compared with distal ACT] < 0.05; Group II 0.76 +/- 0.05 minutes, P [proximal-distal] < 0.01; Group III 0.89 +/- 0.09 minutes, P [proximal-distal] = NS) suggesting more effective esophageal clearance in the proximal esophagus. CONCLUSIONS: Protection of the proximal esophagus from acid reflux is significantly related to the incidence and duration of reflux measured in the distal esophagus. These normal ranges in the upper esophagus will be helpful in the interpretation of upper esophageal pH monitoring data.     

Simultaneous recording of pH in the distal and proximal esophagus]

A 24 hour esophageal pH recording was performed in 46 infants (age: 10 +/- 12 months). Two probes were placed in the proximal and distal esophageal sites respectively. A significant correlation was shown between the upper and lower part of the esophagus for the numbers of acid (pH fall below 4 for at least 15 s) and weakly acid (fall in pH of more than one unit, irrespective of whether or not the pH fell below 4) gastroesophageal reflux (GER), the reflux index and the number of acid GER longer than 5 min. The number of acid GER and the time spent at pH less than 4 at the proximal esophagus were significantly greated in group 1 (reflux index greater than 5% in the distal esophagus, n = 10), than in group 2 (reflux index less than 5% in the distal esophagus, n = 36). The proportion of distal acid and weakly acid reflux reaching the upper esophagus presented with marked variation coefficients. These findings indicate that data obtained in the distal esophagus are poorly predictive of the results in the proximal esophagus, even if infants present high reflux index at the lower esophagus. Weakly acid GER reached the upper esophagus more frequently than acid GER.     

Smaller volume, thickened formulas in the management of gastroesophageal reflux in thriving infants

BACKGROUND: The effect of smaller volume, thickened formulas on gastroesophageal reflux is not clear. METHODS: The frequency of gastroesophageal reflux and duration of acid pH in the esophagus were determined in six thriving infants using extended esophageal pH monitoring. RESULTS: There was a significant reduction in frequency of emesis and gastroesophageal reflux but not the duration of acid pH in the esophagus with the use of infant formula thickened with rice cereal to provide a nutritionally appropriate intake in a smaller volume. CONCLUSIONS: Thickening of formula with rice cereal in a nutritionally balanced form and smaller volume may be an appropriate strategy for reducing frequency of emesis and gastroesophageal reflux in thriving infants.     

Gastroesophageal reflux in patients with cystic fibrosis

Children with cystic fibrosis (CF) and their asymptomatic siblings were surveyed to determine the incidence of symptomatic gastroesophageal reflux. A subgroup of patients with CF with poor nutritional status were studied with esophageal manometry, 24-hour esophageal pH recording, and pulmonary function testing before and after initiation of supplemental continuous nighttime nasogastric feeds. Of 68 patients with CF greater than or equal to 5 years of age, 20.6% experienced regurgitation and 26.5% had heartburn. In the control group of 23 asymptomatic siblings greater than or equal to 5 years of age, none experienced regurgitation and 5.6% had heartburn. Among the patients there was no significant association between symptoms of gastroesophageal reflux and bronchodilator therapy. Eight patients had normal lower esophageal sphincter pressure of 24.8 +/- 8.8 mm Hg and thoracoabdominal pressure gradient of 11.4 +/- 4.6 mm Hg; peristalsis and upper esophageal sphincter pressure were normal. There was a significant increase in reflux episodes, episodes greater than 5 minutes, duration of the longest episode, and percent time esophageal pH was less than 4 in patients, compared with published control data, for the entire 24-hour period and during sleep. During sleep, continuous nasogastric feeding significantly increased episodes of reflux, but did not result in an increase in percent time esophageal pH was less than 4, and was not associated with evidence of aspiration or deterioration in pulmonary function. Our findings indicate that symptoms of gastroesophageal reflux, heartburn, and regurgitation are more frequent in patients with CF than in asymptomatic siblings and that gastroesophageal reflux is significantly more common in patients with CF than in controls. Nighttime nasogastric feedings can safely be used as a means of nutritional rehabilitation in patients with CF.     

Does postoperative pH monitoring predict complicated gastroesophageal reflux in patients with esophageal atresia?

Gastroesophageal reflux (GER) is common after repair of esophageal atresia with a distal tracheoesophageal fistula (EATOF). In a retrospective study we assessed whether early 18-h pH monitoring can predict the development of EATOF-associated gastroesophageal reflux. During 1980–1997, 90 consecutive patients had primary repair for EATOF. Development of GER was classified as favorable if the patient developed no esophagitis or mild esophagitis and needed no antireflux medication, and as unfavorable if the patient developed moderate or secondary esophagitis or required an antireflux procedure. Patients who developed unfavorable GER outcome before pH monitoring or needed secondary reconstruction or those whose endoscopic follow-up data were insufficient were excluded. Eighteen-hour pH monitoring was considered pathologic if esophageal pH was <4 more than 10% of the recorded time or 5% of the recorded time minus 2 h after each meal, or if there were more than three preprandial reflux periods lasting longer than 5 min. A total of fifty patients were included into the study. pH monitoring was performed at the median age of 9.2 (range 2.5–95.0) months and classified as pathologic in 10 and normal in 40 patients. After a median follow-up of 59 (0.3–217.6) months, nine of 10 (90%) patients with pathologic pH monitoring and five of 40 (12.5%) patients with normal pH monitoring developed unfavorable outcomes (p<.05). We conclude that early pH monitoring predicts the development of significant GER, but because 12.5% of patients with normal early pH monitoring also developed significant GER, early pH monitoring alone does not rule out the development of significant GER.     

Gastroesophageal reflux disease in 2006. The imperfect diagnosis

There continues to be significant controversy related to diagnostic testing for gastroesophageal reflux disease (GERD). Clearly, barium contrast fluoroscopy is superior to any other test in defining the anatomy of the upper gastrointestinal (UGI) tract. Although fluoroscopy can demonstrate gastroesophageal reflux (GER), this observation does not equate to GERD. Fluoroscopy time should not be prolonged to attempt to demonstrate GER during barium contrast radiography. There are no data to justify prolonging fluoroscopy time to perform provocative maneuvers to demonstrate reflux during barium contrast UGI series. Symptoms of GERD may be associated with physiologic esophageal acid exposure measured by intraesophageal pH monitoring, and a significant percentage of patients with abnormal esophageal acid exposure have no or minimal clinical symptoms of reflux. Abnormal acid exposure defined by pH monitoring over a 24-h period does not equate to GERD. In clinical practice presumptive diagnosis of GERD is reasonably assumed by substantial reduction or elimination of suspected reflux symptoms during therapeutic trial of acid reduction therapy.     

Continuous 24-hour esophageal pH monitoring in 285 asymptomatic infants 0-15 months old

A continuous 24-h esophageal pH monitoring was performed in 283 asymptomatic infants between 5 days and 15 months old. Several parameters (reflux index, duration of the longest reflux episode, number of reflux episodes in 24 h, number of reflux episodes greater than 5 min in 24 h) were studied in different groups of infants according to their age: 5-15 days old, 24-37 days old, 3.5-4.5 months old, 5.5-6.5 months old, 7.5-8.5 months old, 14-16 months old. For all parameters we obtained statistically significant different results in infants younger and older than 4 months. The 24-h esophageal pH monitoring is an investigation technique in physiological circumstances in order to establish normal ranges for gastroesophageal reflux in asymptomatic infants.