Can pH monitoring reliably detect gastro-oesophageal reflux in preterm infants?

Oral Care Associated With Less Microaspiration in Ventilated Cardiac Patients

Aspiration is common in mechanically ventilated patients and may predispose patients to aspiration pneumonia, chemical pneumonitis, and chronic lung damage. Pepsin A is a specific marker of gastric fluid aspiration and is often detected in ventilated pediatric patients. We investigated the effect of oral care and throat suctioning in the detection of pepsin A in tracheal aspirates (TAs) up to 4 hours after these procedures.

Methods

Twelve pediatric patients between age 2 weeks to 14 years who underwent intubation for cardiac surgery were enrolled in this study. Six of the 12 patients were consented before their surgery with initial specimen collected at the time of intubation and last one shortly before extubation (intubation duration < 24 hours). The remaining 6 patients were consented after cardiac surgery. All specimens were collected per routine care per respiratory therapy protocol and shortly before extubation (intubation duration > 24 hours). Tracheal fluid aspirates were collected every 4 to 12 hours in the ventilated patients. Enzymatic assay for gastric pepsin A and protein determination were performed. The time of oral care and throat suctioning within 4 hours prior was recorded prospectively.

Results

A total of 342 TA specimens were obtained from the 12 intubated pediatric patients during their course of hospitalization; 287 (83.9%) showed detectable total pepsin (pepsin A and C) enzyme activity (> 6 ng/mL) and 176 (51.5%) samples had detectable pepsin A enzyme levels (>6 ng/mL of pepsin A). Only 29 samples of 76 samples (38.2%) had evidence of microaspiration after receiving oral care, while 147 of 266 (55.3%) samples were pepsin A positive when no oral care was provided. Odds ratio is 0.50 (Cl 0.30-0.84), and the number needed to treat is 5.8 (Confidence interval 3.4-22.3). Testing air filters for pepsin was not beneficial.

Conclusion

Oral care is a highly effective measure to prevent microaspiration of gastric fluid in ventilated pediatric patients. The number needed to treat (5.8) suggests this is a very effective prevention strategy. Our study suggests that pepsin A is a useful and sensitive biomarker that allows identification of gastric aspiration.

The lipoprotein NlpD in Cronobacter sakazakii responds to acid stress and regulates macrophage resistance and virulence by maintaining membrane integrity

Cronobacter sakazakii, an emerging opportunistic pathogen, is implicated in severe foodborne outbreak infections in premature and full-term infants. Generally, acid tolerance is vital for the pathogenesis of foodborne pathogens; however, its role in C. sakazakii virulence remains largely unknown. To screen out acid-tolerance determinants from transposon mutants, anovel counterselection method using gentamicin and acid was developed. Using the counterselection method and growth assay, we screened several acid-sensitive mutants and found that nlpD encodes an acid-resistance factor in C. sakazakii. 

Compared to the wild-type strain, the nlpD mutant exhibited attenuated virulence in a rat model. Using macrophage THP-1 cells and a pH probe, we verified that nlpD enables bacteria to resist macrophages by resisting acidification. Finally, we confirmed that nlpD maintains C. sakazakii membrane integrity in acid using propidium iodide permeabilization assays via flow cytometry. Our results confirm that nlpD is a novel virulence factor that permits C. sakazakii to survive under acid stress conditions. Considering that NlpD is a conserved lipoprotein located in the bacterial outer membrane, NlpD could be used as a target for drug development.

Use of a non-invasive accelerometric method for diagnosing gastroesophageal reflux in premature infants

OBJECTIVE

To evaluate the clinical usefulness of a non-invasive accelerometric device to diagnose GER in preterm babies.

STUDY DESIGN

An accelerometer was taped over the sub-xiphoid process in 110 preterm (GA 29.6 ± 3.3 wk) infants (133 studies). Low frequency, sub-audible signals were captured via digital recording (sampling rate 200 Hz), then re-sampled (rate = 60 Hz) to create a spectrogram (focused range 0-30 Hz). Mean amplitude in the focused range was calculated.

RESULTS

Of 85 studies with simultaneous pH-metry and accelerometry, 18 had concurrent positive and 23 had concurrent negative scores, 42 had negative pH scores when accelerometry was positive (≥1 µV), consistent with non-acid reflux. Eleven infants at high risk of aspiration received surgical interventions. All but 1 had negative pH scores while 10/11 had positive accelerometry.

CONCLUSIONS

The non-invasiveness of this accelerometric technique allows for GER screening and for repeated testing to assess efficacy of interventions.

Prolonging gavage feeds for reduction of gastroesophageal reflux in infants

OBJECTIVE

To determine if prolonging gavage feedings in infants for ≥60 min is associated with decreased gastroesophageal reflux (GER) compared with bolus feeding using multiple-channel intraluminal impedance with pH probe (MII-pH).

STUDY DESIGN

Retrospective analysis of infants who underwent MII-pH between October 2009 and July 2018 and received gavage feedings. Infants were divided into two groups: bolus (<30 min) or prolonged (≥60 min). Symptoms, number of reflux events and percent time pH < 4 was compared.

RESULT

Fifty-eight infants underwent evaluation. Thirty-one (54%) received bolus gavage feedings and 27 (46%) received prolonged feedings. Groups differed in postmenstrual age. Total reflux episodes were significantly lower with prolonged feeding (median 19 vs. 28 episodes, p = 0.015), with no difference in acid exposure time. There was no significant difference in GER symptoms between the two groups.

CONCLUSION

Prolongation of gavage feedings was associated with decreased total numbers of GER events without reduction in GER symptoms.

A New, Noninvasive Accelerometric Method for Diagnosing Acid andNon-Acid Gastroesophageal Reflux in Premature Infants: Proof of Concept

Non-acid reflux is common in premature neonates. Current methods of diagnosing gastroesophageal reflux (GER) such as pH probes, multichannel impedance monitoring, X-rays, or endoscopy are either invasive or unable to diagnose non-acid reflux. Passage of a naso-esophageal tube is uncomfortable. Imaging studies are of short duration and may miss reflux entirely. Herein, we present proof of concept of a noninvasive accelerometric device that detects acid and non-acid reflux in premature infants. An accelerometer was taped over the subxiphoid process in patients suspected of having GER who were already scheduled for pH probe or multichannel impedance monitoring. The largest cohort was preterm infants, but term infants and toddlers were also studied. Low-frequency subaudible signals were obtained on a digital recorder (sampling rate 200 Hz) signals. Fast Fourier transforms graphically displayed the frequency and amplitude of signals. Data were then resampled at a rate of 60 Hz to create a spectrogram with a focused range of 0-30 Hz representing reflux-associated events. Proof of concept was attained through successful comparison with results from concurrent pH probes, multichannel impedance recordings, and ultrasound studies. We have thus validated accelerometry as a noninvasive method for assessing both acid and non-acid GER. The noninvasiveness of this diagnostic modality allows for repeated testing to assess the efficacy of anti-reflux medications, even when patients remain on antacids. This technology allows for more rational management of patients with GER and represents a major advance in the diagnosis and treatment of GER.

Detection of gastro-oesophageal reflux in the neonatal unit

AIM

To determine whether a pH probe or multichannel intraluminal impedance (MII) more frequently detected gastro-oesophageal reflux and test the hypothesis that acid reflux was associated with lower baseline impedance.

METHODS

A prospective study of infants in whom reflux was suspected and evaluated using combined pH and multichannel impedance. Studies were considered abnormal if the acid index was >10% or there were >79MII reflux events in 24 hours. The acid index was the percentage of total study time with a pH

RESULTS

Forty-two infants [median gestational age 31 (range 23-42) weeks] were assessed. Only nine infants (21%) had abnormal studies, seven detected by pH monitoring, one by MII monitoring and one by both techniques (p = 0.04). After correcting for gestational age and post-natal age, baseline impedance remained negatively correlated with the acid index (r = -0.34, p = 0.038) and the maximum ACT (r = -0.44, p = 0.006).

CONCLUSION

Clinical suspicion of reflux was frequently incorrect, and reflux was more frequently detected by a pH probe. The inverse relationship of acid reflux to baseline impedance suggests that mucosal disruption may result from acid reflux in this population.

Collapse

Key Words

• Baseline oesophageal impedance
• Multichannel intraluminal impedance
• pH study

Collapse

MESH Headings Collapse

Grants Collapse

Affiliation(s)

Thomas Rossor MRC Centre in Allergic Mechanisms of Asthma, King's College London, London, UK Department of Women and Children's Health, School of Life Course Sciences, Faculty of Life Sciences and Medicine, King's College London, London, UK
Ingran Lingam Neonatal Intensive Care Centre, King's College Hospital NHS Foundation Trust, London, UK
Abdel Douiri Department of Primary Care and Public Health Sciences, King's College London, London, UK NIHR Biomedical Research Centre, Guy's and St Thomas' NHS Foundation Trust, King's College London, London, UK
Ravindra Bhat Neonatal Intensive Care Centre, King's College Hospital NHS Foundation Trust, London, UK
Anne Greenough MRC Centre in Allergic Mechanisms of Asthma, King's College London, London, UK Department of Women and Children's Health, School of Life Course Sciences, Faculty of Life Sciences and Medicine, King's College London, London, UK NIHR Biomedical Research Centre, Guy's and St Thomas' NHS Foundation Trust, King's College London, London, UK

Collapse

Investigation and management of gastro-oesophageal reflux in United Kingdom neonatal intensive care units

AIM

In 2004, wide variation in the investigation and management of gastro-oesophageal reflux (GOR) of infants on UK major neonatal units was demonstrated. Our aim was to resurvey neonatal practitioners to determine current practice and whether it was now evidence based.

METHODS

A questionnaire was sent to all 207 UK neonatal units.

RESULTS

Responses were obtained from 84% of units. The most frequent 'investigation' was a trial of therapy (83% of units); pH studies were used in 38%, upper GI contrast studies in 19% and multichannel intraluminal impedance (MII)/pH studies in 5%. Only six units suggested a threshold for an abnormal pH study and two units for an abnormal MII study. Infants were commenced on antireflux medication without investigation always in 32% of units, often in 29%, occasionally in 19% and only never in 1%. Gaviscon was used as first line treatment in 60% of units, and other medications included ranitidine in 53%, thickening agents in 27%, proton pump inhibitors in 23%, domperidone in 22% and erythromycin in 6%.

CONCLUSION

There remains a wide variation in diagnostic and treatment strategies for infants with suspected GOR on neonatal intensive care units, emphasising the need for randomised trials to determine appropriate GOR management.

Pepsin in saliva as a biomarker for oropharyngeal reflux compared with 24-hour esophageal impedance/pH monitoring in pediatric patients

BACKGROUND

Pepsin in saliva is a proposed biomarker for oropharyngeal reflux. Pepsin may be prevalent in saliva from subjects with gastro-esophageal reflux and may correlate with proximal reflux by intraluminal impedance/pH monitoring (MII/pH).

METHODS

Patients (3 days to 17.6 years, n=90) undergoing 24-hour MII/pH monitoring and asymptomatic controls (2 months to 13.7 years, n=43) were included. Salivary pepsin was determined using a pepsin enzyme-linked immunosorbent assay. Eight saliva samples were collected from patients undergoing 24-hr MII/pH: (i) before catheter placement, (ii) before and 30 minutes after each of three meals, and (iii) upon awakening. One sample was collected from each control.

KEY RESULTS

In MII/pH subjects, 85.6% (77/90) had at least one pepsin-positive sample compared with 9.3% (4/43) in controls. The range of pepsin observed in individual subjects varied widely over 24 hours. The average pepsin concentration in all samples obtained within 2 hours following the most recent reflux event was 30.7±135 ng/mL, decreasing to 16.5±39.1 ng/mL in samples collected more than 2 hours later. The frequency of pepsin-positive samples correlated significantly with symptom index (r_S =0.332, P=.0014), proximal (r_S =0.340, P=.0010), and distal (r_S =0.272, P=.0095) MII events.

CONCLUSIONS & INFERENCES

Concentration of salivary pepsin may not be an accurate measure of severity of reflux because of the wide range observed in individuals over 24 hours. Saliva samples must be obtained soon after a reflux event. Defining a regimen for optimal saliva collection may help to achieve the goal of using salivary pepsin as a biomarker for oropharyngeal reflux.

CLINICAL TRIAL REGISTRY

NCT01091805.

Neonatal Histamine-2 Receptor Antagonist and Proton Pump Inhibitor Treatment at United States Children's Hospitals

OBJECTIVE

To determine treatment frequency and duration of histamine-2 receptor antagonist (H2RA)/proton pump inhibitor (PPI) use among infants hospitalized within US children's hospital neonatal intensive care units and evaluate diagnoses/demographic factors associated with use.

STUDY DESIGN

We retrospectively analyzed a cohort of neonatal intensive care unit infants admitted to 43 US children's hospitals within the Pediatric Health Information System database between January 2006 and March 2013 to determine H2RA/PPI treatment frequency, timing/duration of treatment, factors associated with use, percent of infants remaining on treatment at discharge, and interhospital prescribing variation. We used a modified Poisson regression to calculate the adjusted probability of infants ever receiving H2RAs/PPIs in relation to diagnosis, gestation, and sex.

RESULTS

Of the 122 002 infants evaluated, 23.8% (n = 28 989) ever received an H2RA or PPI; 19.0% received H2RAs (n = 23 187), and 10.5% (n = 12 823) received PPIs. Extremely preterm infants and term infants were the most likely to receive H2RA and PPI treatment. Infants with gastroesophageal reflux disease (relative risk [RR] = 3.13) and congenital heart disease (RR = 2.41) had the highest H2RA/PPI treatment probabilities followed by those with an ear, nose, and throat diagnosis (RR = 2.34; P < .05). The majority of treated infants remained treated at discharge.

CONCLUSIONS

Despite limited evidence and increasing safety concerns, H2RAs/PPIs are frequently prescribed to extremely preterm neonates and those with congenital anomalies and continued through discharge. Our findings support the need for innovative studies to examine the comparative effectiveness and safety of H2RA/PPIs vs no treatment in these high-risk neonatal populations.

Comparison of the efficiencies of esophageal manometry, vector volume analysis and esophagus pH monitoring in the diagnosis of gastroesophageal reflux

AIM

In this study, we aimed to compare the superiorities of esophageal manometry, vector volume analysis and 24-hour pH meter studies in showing gastroesophageal reflux disease.

MATERIAL AND METHODS

The files of the patients who presented to pediatric surgery and pediatric gastroenterology outpatient clinics of our hospital with suspicious gastroesophageal reflux disease between 2011 and 2012 and who were investigated were examined and 21 patients whose investigations had been completed were included in the study. The patients were evaluated by treatment method and were divided into three groups as Group 1 who were followed up with medical treatment, Group 2 in whom surgical intervention was performed and Group 3 who were not treated. Chi-square test was used in evaluation of the categorical variables, Kruskal Wallis test was used in comparison of the mean values between the groups and Dunn test was used in subgroup analyses when Kruskal Wallis test was found to be significant. A p value of <0.05 was considered statistically significant.

RESULTS

Thirteen of 21 patients included in the study were female and eight were male. The mean age of the patients was 5.71 years (one-16 years). In the 24-hour pH monitoring study, the mean reflux index was found to be 48.7% in Group 1, 42.4% in Group 2 and 28.3% in Group 3. In esophageal manometry studies, the pressure difference at lower esophageal sphincter (LES) was found to be 13,4 cm H2O in Group 1, 31.8 cm H2O in Group 2 and 4.3 cmH2O in Group 3. In vector volume analyses, the mean vector volume was calculated to be 96.01 cm(3) in Group 1, 2 398.9 cm(3) in Group 2 and 196.3 cm(3) in Group 3. In the 24-hour pH monitoring study, a statistically significant difference (p<0.05) was found in terms of showing reflux, whereas statistical significance could not be shown in terms of need for surgical treatment or need for medical treatment in any other method (p>0.05).

CONCLUSIONS

Twenty-four-hour pH monitoring was found to be efficient in making a diagnosis of gastroesophageal reflux disease, whereas esophageal manometry and vector volume analyses were not found to be efficient.

The effects of acidification on human milk's cellular and nutritional content

OBJECTIVE

Fortification of human milk for preterm infants is necessary and a common newborn intensive care practice. Currently, acidified human milk as part of a human milk fortifier is being fed to preterm infants. However, there are little data on the acidification effects on mother's milk. The aim of this study is to determine the effects of acidification on human milk's cellular and nutritional composition.

STUDY DESIGN

One hundred milk samples were collected from eight mothers who had infants in the neonatal intensive care unit. All milk samples were frozen at 4 °C. The frozen samples were thawed and divided into two equal aliquots, control and acidified. The control milk sample had its pH determined while the other sample was acidified to pH 4.5. Each milk sample was examined for pH, white cells, total protein, creamatocrit, lipase activity and free fatty acids.

RESULT

Mean pH of the human milk control was 6.8 ± 0.1 (M ± s.d.) with the acidified milk at 4.5 ± 0.1. Acidification caused a 76% decrease in white cells, a 56% decrease in lipase activity and a 14% decrease in the total protein but a 36% increase in the creamatocrit.

CONCLUSION

Acidification of human milk causes significant changes of the milk's cellular and nutritional components that may not be beneficial to preterm infants.

Detection of pepsin in mouth swab: correlation with clinical gastroesophageal reflux in preterm infants

OBJECTIVE

To study the relationship between pepsinogen/pepsin in a mouth swab and clinical gastroesophageal reflux (GER) in preterm infants.

METHODS

Preterm infants (birth weight ≤ 2000 g) on full enteral feeds were enrolled. Mouth swabs from cheek and below the tongue were collected one, two and three hours after feeding. An enzymatic assay with substrate fluorescein isothiocyanate-casein was used to detect pepsin A and C activities with further confirmation by western blot. Blinded investigators reviewed the infant's medical record to clinically diagnose GER.

RESULTS

A total of 101 premature infants were enrolled. Pepsinogen/pepsin was detected in 45/101 (44.5%) infants in at least one sample. A clinical diagnosis of GER was made in 36/101 (35.6%) infants. Mouth swabs were positive in 26/36 (72%) infants with clinical GER and only 19/65 (29%) infants without GER (p < 0.001). Similarly, the levels of pepsinogen/pepsin A and C were higher in the mouth swabs of infants with clinical GER.

CONCLUSION

The detection of pepsinogen/pepsin in a mouth swab correlates with clinical GER in premature infants.

Myth: gastroesophageal reflux is a pathological entity in the preterm infant

There is concern about possible consequences of gastroesophageal reflux (GER) in preterm infants. GER is perceived to be a frequent condition in these infants, often causing an exhaustive investigation and expensive therapy. We review current evidence for and against an association between GER and apnea, failure to thrive, wheezing and respiratory diseases. Although there are some limitations to the methodologies currently used for detecting GER, there is clearly a lack of unequivocal evidence supporting a causal relationship between GER and its assumed consequences, particularly in preterm infants. Despite physiologic data that stimulation of laryngeal efferents by GER may induce apnea, there is little evidence for a causal relationship between GER and apnea. Studies on preterm infants with failure to thrive have also not demonstrated an association between the latter and GER in most cases, and there is equally little evidence for a casual relationship with respiratory problems. Therefore, we believe that GER in preterm infants is only rarely associated with serious consequences and existing evidence does not support the widespread use of anti-reflux medications for treatment of these signs in this age group. An improvement of methods to identify the few preterm infants at risk for developing serious consequences of GER is urgently needed.

Diagnosis of gastroesophageal reflux disease in infants

Gastroesophageal reflux is commonly encountered in the infant population. Most children will outgrow their reflux but some develop pervasive disease and require medical or surgical treatment. Many tools exist for use in the workup of pediatric gastroesophageal reflux disease; however, the most effective method of diagnosis is not clear. Delineating which patients will benefit from more definitive therapy is a remarkable challenge in this group, often borrowing tools and principles from the adult patient population. Therefore, we reviewed the available literature to critically evaluate the merits and limitations of the current diagnostic modalities available for the evaluation of infantile gastroesophageal reflux.

Regurgitation in healthy and non healthy infants

Uncomplicate regurgitation in otherwise healthy infants is not a disease. It consists of milk flow from mouth during or after feeding. Common causes include overfeeding, air swallowed during feeding, crying or coughing; physical exam is normal and weight gain is adequate. History and physical exam are diagnostic, and conservative therapy is recommended. Pathologic gastroesophageal reflux or gastroesophageal reflux disease refers to infants with regurgitation and vomiting associated with poor weight gain, respiratory symptoms, esophagitis. Reflux episodes occur most often during transient relaxations of the lower esophageal sphincter unaccompanied by swallowing, which permit gastric content to flow into the esophagus. A minor proportion of reflux episodes occurs when the lower esophageal sphincter fails to increase pressure during a sudden increase in intraabdominal pressure or when lower esophageal sphincter resting pressure is chronically reduced. Alterations in several protective mechanisms allow physiologic reflux to become gastroesophageal reflux disease; diagnostic approach is both clinical and instrumental: radiological series are useful to exclude anatomic abnormalities; pH-testing evaluates the quantity, frequency and duration of the acid reflux episodes; endoscopy and biopsy are performed in the case of esophagitis. Therapy with H2 receptor antagonists and proton pump inhibitors are suggested.

Combined oesophageal impedance-pH monitoring in preterm newborn: comparison of two options for layout analysis

Gastro-oesophageal reflux (GOR) is common in preterm infants. Combined multichannel intraluminal impedance and pH monitoring (pH-MII) is emerging as an useful tool to study both acid and non-acid GOR in this population. We aimed to highlight main advantages and limits of pH-MII in preterm infants and to test whether the inclusion of GOR episodes detected only by pH monitoring details better the features of GOR. Fifty-two symptomatic preterm infants underwent a 24-hour, continuous and simultaneous measurement of pH-MII. Each layout was analyzed using two different options: option 1 included GOR episodes detected by MII and then classified as acid or non-acid according to the associated pH change; option 2 included GOR episodes detected by MII and also GOR episodes detected only by pH sensor. By adopting option 1, a total number of 2834 GOR episodes was detected by MII: 2162 of them were characterized as non-acid and 672 were characterized as acid. The median (range) number of acid MII-GOR episodes was 10 (1-52); the median (range) number of non-acid MII-GOR episodes was 36.5 (2-119). Median (range) acid MII-GOR-bolus exposure index was 0.28% (0.02-2.73%); median (range) non-acid MII-GOR-bolus exposure index was 1.03% (0.06-38.15%). By adopting option 2, an average of 53.2 acid GOR episodes and an average of 11% oesophageal exposure to acid GOR more than by option 1 was detected. An accurate and detailed description of GOR in preterm infants can be obtained only by including in the analysis all acid GOR episodes detected by pH sensor.

Clinical predictors of abnormal esophageal pH monitoring in preterm infants

BACKGROUND

Risk factors for gastroesophageal reflux disease in preterm neonates have not been yet clearly defined.

AIM

To identify factors associated with increased esophageal acid exposition in preterm infants during the stay in the neonatal unit.

METHODS

A case-control study in preterm infants who had undergone prolonged monitoring of distal esophageal pH, following clinical indication. Eighty-seven preterms with reflux index (percentage of total time of esophageal pHmetry) > or = 10% (cases) and 87 unpaired preterms were selected with reflux index <10% (controls). Demographic variables, signs and symptoms, main diagnoses and some aspects of treatment were studied. Simple and multiple logistic regression analysis adjusted for birthweight and postconceptional age at the pH study were used.

RESULTS

The factors associated with a greater chance of reflux index > or = 10% in preterms were: vomiting, regurgitation, Apnea, female gender. The variables that were associated with a lower frequency of increased reflux index were: volume of enteral intake at the onset of symptoms > or = 147 mL/kg/day, and postnatal corticoid use.

CONCLUSIONS

Vomiting, regurgitation, apnea, female gender and acute respiratory distress during the first week of life were variables predictive of increased esophageal acid exposition in preterm infants with birthweight <2000 g. Bronchopulmonary dysplasia and use of caffeine were not associated with reflux index > or = 10%.

Differential diagnosis of apneas in preterm infants

Clinically relevant apneas, which are common in preterm infants, may adversely affect later neuropsychological condition in this group of patients. Pharmacotherapy to stimulate respiratory functions may be unsuccessful. Polygraphic recording may help in the differential diagnosis of these clinically relevant events. Twenty-nine preterm neonates born before 36 weeks of gestational age were examined using polygraphic recording (respiration--two channels, perioral electromyography, oxygen saturation, heart rate, electroencephalography, electrocardiography, electrooculography). The examination was ordered by the attending physician after an unsuccessful treatment of apnea by Aminophylline, and it should contribute to the clarification of the causes of these events. In the course of the polygraphic examinations, altogether 63 episodes were recorded during which the pulse oximeter alarm signal was set off. In 42 cases, the alarm signal was set off in events during which SaO(2) fell below 85%. In the remaining 21 cases, the alarm signal was set off in episodes during which early bradycardia below 90/min occurred. The onset of apnea was very often associated with the phasic increase of the perioral electromyography and with electroencephalography arousal reaction. Because of suspicion that these apneas may be triggered by episodes of gastroesophageal reflux, the interruption of the Aminophylline treatment and setting up an antireflux regimen were recommended. These therapeutic measures had a positive effect: The frequency of alarm signals decreased within 48 h by a statistically significant 50%. In cases where the pharmacotherapy of apnea by stimulation of respiratory functions is not successful, differential diagnostic analysis should be performed. Polygraphy may contribute to the clarification of the causes underlying clinically relevant apneas in a view of newly described polygraphic signs. It is feasible to suspect, based on these signs, that gastroesophageal reflux is the cause for clinically significant apneas in that case.

Pepsin, a marker of gastric contents, is increased in tracheal aspirates from preterm infants who develop bronchopulmonary dysplasia

OBJECTIVE

The objective of this study was to study the association between pepsin in tracheal aspirate samples and the development of bronchopulmonary dysplasia in preterm infants.

METHODS

Serial tracheal aspirate samples were collected during the first 28 days from mechanically ventilated preterm neonates. Bronchopulmonary dysplasia was defined as the need for supplemental oxygen at 36 weeks' postmenstrual age. An enzymatic assay with a fluorescent substrate was used to detect pepsin. Total protein was measured by the Bradford assay to correct for the dilution during lavage. Immunohistochemistry using antibody against human pepsinogen was performed in 10 lung tissue samples from preterm infants.

RESULTS

A total of 256 tracheal aspirate samples were collected from 59 preterm neonates. Pepsin was detected in 234 (91.4%) of 256 of the tracheal aspirate samples. Twelve infants had no bronchopulmonary dysplasia, 31 infants developed bronchopulmonary dysplasia, and 16 infants died before 36 weeks' postmenstrual age. The mean pepsin concentration was significantly lower in infants with no bronchopulmonary dysplasia compared with those who developed bronchopulmonary dysplasia or developed bronchopulmonary dysplasia/died before 36 weeks' postmenstrual age. Moreover, the mean pepsin level was significantly higher in infants with severe bronchopulmonary dysplasia compared with moderate bronchopulmonary dysplasia. The mean pepsin level in tracheal aspirate samples from the first 7 days was also lower in infants with no bronchopulmonary dysplasia compared with those who developed bronchopulmonary dysplasia or developed bronchopulmonary dysplasia/died before 36 weeks' postmenstrual age. Pepsinogen was not localized in the lung tissues by immunohistochemistry.

CONCLUSION

The concentration of pepsin was increased in the tracheal aspirate of preterm infants who developed bronchopulmonary dysplasia or died before 36 weeks' postmenstrual age. Recovery of pepsin in tracheal aspirate samples is secondary to gastric aspiration, not by hematogenous spread or local synthesis in the lungs. Chronic aspiration of gastric contents may contribute in the pathogenesis of bronchopulmonary dysplasia.

Infant apnea and gastroesophageal reflux: a critical review and framework for further investigation

Gastroesophageal reflux and apnea of prematurity are both common occurrences in premature infants. However, a causal relationship between the two remains controversial. Strong physiologic evidence indicates that a variety of protective reflex responses may elicit laryngeal adduction and apnea. Although a potential link between gastroesophageal reflux and apnea may exist through this pathway, clinical studies can be cited to either support or refute such a link in premature infants. The majority of gastroesophageal reflux episodes do not appear to be related to apnea. In a specific subset of events, a causal relationship may exist. Whether this is related to the character of the reflux episode or to a predisposition in a subpopulation of infants is unclear. This review presents the evidence for and against an association between gastroesophageal reflux and apnea, discusses techniques used in their evaluation, and identifies approaches for future investigation.

Acid gastroesophageal reflux in convalescent preterm infants: effect of posture and relationship to apnea

Concerns regarding gastroesophageal reflux (GER) and associated apnea episodes result in some practitioners having convalescent, prematurely born infants sleep in the prone position. We have tested the hypothesis that such infants would not suffer from clinically important acid GER or associated apnea episodes more in the supine compared with the prone position. Lower esophageal pH was measured and videopolysomnographic recordings of nasal airflow, chest and abdominal wall movements, electrocardiographic activity, and oxygen saturation were made on two successive days of 21 premature infants (median gestational age 28 wk) at a median postmenstrual age (PMA) of 36 wk. On each day, the infants were studied prone and supine. The acid reflux index was higher in the supine compared with the prone position (median 3% versus 0%, p = 0.002), but was low in both positions. The number of obstructive apnea episodes per hour was higher in the supine position (p = 0.008). There were, however, no statistically significant correlations between the amount of acid GER and the number of either obstructive or total apnea episodes in either the supine or prone position. Supine compared with prone sleeping neither increases clinically important acid GER nor obstructive apnea episodes associated with acid GER in asymptomatic, convalescent, prematurely born infants.

Multichannel intraluminal impedance to detect relationship between gastroesophageal reflux and apnoea of prematurity

BACKGROUND

The association between gastroesophageal reflux and apnoea of prematurity is still controversial. Available data are biased by the heterogeneity of the infants enrolled as regard to some confounding factors and by the use of the traditional pH monitoring that is unable to detect non acid reflux events which might be prevalent in infants receiving frequent milk feeding. Multichannel intraluminal impedance has been recently introduced as a pH-independent method to investigate the bolus transport in hollow organs.

OBJECTIVE

To assess if combined multichannel intraluminal impedance-pH study could be useful to detect an association between gastroesophageal reflux and apnoea of prematurity.

METHODS

We prospectively evaluated a group of premature infants with apnoea of prematurity in absence of any confounding factors (ventilatory support, treatment with caffeine, permanent nasogastric tube, post-natal age older than 30 days) by simultaneous recording of 24-h multichannel intraluminal impedance-pH and cardiorespiratory monitoring. A temporal relationship between an apnoea and a reflux event was considered if both commenced within 20s of each other.

RESULTS

Six premature infants [three male; median gestational age 31 weeks (range 27-36); birth weight 1335g (range 1200-2350); age at study 17 days (range 7-28)] were studied. A total of 405 reflux events [306 (76%) weakly acid and 99 acid reflux] and 142 apnoeas were detected. The frequency of apnoeas occurring during the reflux events period was significantly greater than the one calculated for reflux-free period [0.42/min (0.00-1.28) versus 0.016/min (0.003-0.028); p<0.05]. The sub-analysis based on chemical composition and duration of refluxate showed that the frequency of apnoeas associated with weakly acid reflux events was significantly greater than the one calculated for reflux-free period [0.416/min (0.00-1.30) versus 0.016/min (0.003-0.028), respectively; p<0.05] and that the frequency of apnoeas occurring during reflux events longer than 30s was significantly higher than those occurring during shorter reflux events (22% versus 11%; p<0.004).

CONCLUSION

Our data show that weakly acidic reflux events are more prevalent than acid reflux events in premature infants, confirming the need for the use of multichannel intraluminal impedance-pH monitoring for diagnosis of gastroesophageal reflux in those patients. Gastroesophageal reflux and apnoea of prematurity are both common occurrences and, in our experience, may be temporally related especially as regard to weakly acid refluxate and reflux events longer than 30s.

Diagnosis of gastro-oesophageal reflux in preterm infants: sonography vs. pH-monitoring

OBJECTIVES

To compare the ultrasound examination with pH-metry in order to evaluate the diagnostic accuracy of sonography for diagnosis of gastro-oesophageal reflux (GOR) in preterm infants.

METHODS

A prospective study was conducted on 31 premature infants <34 weeks with clinically diagnosed GOR. First, they underwent 24-hour pH-monitoring; successively, the sonographic assessment was performed within 12 h after pH-monitoring. The two operators who performed the pH-monitoring and sonography respectively, were unaware of each other's results.

RESULTS

Twenty-one patients (67.7%) had significant GOR with a reflux index >5 (GOR group). The median (range) reflux index in this group was 9.19% (6.04-20.1). Ten newborns (32.3%) did not have significant GOR with a reflux index <5. Sonography was positive for GOR in 8 patients (25.8%); all 8 infants with sonographic diagnosis of GOR had a reflux index >5. Therefore, sonographic diagnosis did not produce false positives. Sonography was negative in 23 newborns (74.2%); 13 of these were positive to pH-monitoring and may therefore be considered as false negatives. Respect to continuous 24-hour pH-monitoring, sonography showed a specificity of 100% but a very low sensitivity of 38% with a positive prediction value of 100% and a negative prediction value of 43%.

CONCLUSIONS

Sonography should not replace 24-hour pH monitoring for detecting GOR in preterm infants. However, sonography has a very high specificity and a positive predictive value of 100%. When clinicians suspect GOR in preterm infants, it could be useful for selection of cases to refer for pH-metry.

Pepsin, a reliable marker of gastric aspiration, is frequently detected in tracheal aspirates from premature ventilated neonates: relationship with feeding and methylxanthine therapy

OBJECTIVES

To determine the frequency of pepsin detection in tracheal aspirate (TA) samples of mechanically ventilated premature neonates and its association with feedings and methylxanthine therapy.

PATIENTS AND METHODS

Serial TA samples (days 1, 3, 5, 7, 14, 21, 28 and >28 days) were collected from premature neonates receiving ventilatory support. An enzymatic assay with a fluorescent substrate was used to detect pepsin. Pepsin was also measured in 10 serum samples collected in conjunction with the TA samples from 8 neonates.

RESULTS

A total of 239 TA samples was collected from 45 premature neonates (mean birth weight, 762 +/- 166 g; mean gestational age, 25.5 +/- 1.5 wk). Pepsin was detectable in 222 of 239 TA samples (92.8%) and in none of the serum samples. Pepsin was significantly lower on day 1 (mean, 170 +/- 216 ng/mL) when compared with all other time points (P < 0.05). Mean concentration of pepsin was significantly lower when infants were unfed (265 +/- 209 ng/mL) compared with levels during feeding (390 +/- 260 ng/mL, P = 0.02). The mean level of pepsin was significantly higher in infants during xanthine therapy (419 +/- 370 ng/mL) compared with no xanthine therapy (295 +/- 231 ng/mL, P = 0.037).

CONCLUSION

Pepsin, a marker of gastric contents, was detected in more than 92% of TA samples from premature infants on mechanical ventilation. The level of pepsin was higher in fed infants when compared with unfed infants. Xanthine therapy was also associated with increased pepsin in TA samples. Chronic aspiration of gastric contents may worsen lung disease in premature infants.

Twenty-four-hour esophageal impedance-pH monitoring in healthy preterm neonates: rate and characteristics of acid, weakly acidic, and weakly alkaline gastroesophageal reflux

OBJECTIVE

Gastroesophageal reflux is a physiologic process and is considered pathologic (gastroesophageal reflux disease) when it causes symptoms or results in complications. It is common in preterm infants and occurs in healthy neonates. Twenty-four-hour pH monitoring commonly is used in children for diagnosis of gastroesophageal reflux disease, and abnormal reflux is considered with detection of increased esophageal acid exposure. However, in neonates, relatively few gastroesophageal reflux episodes cause esophageal acidification to pH < 4. Premature infants receive frequent feeds, which can induce a weaker acid secretory response than that observed in older infants and adults. As a consequence, gastric pH may be > 4 for prolonged periods, and reflux of gastric contents might be less acidic or even alkaline. Esophageal impedance monitoring can detect weakly acidic and even alkaline gastroesophageal reflux. The role of weakly acidic reflux in the pathophysiology of gastroesophageal reflux disease in preterm infants is not clear. To date, studies that have used impedance-pH in neonates assessed the association between nonacid reflux and cardiorespiratory symptoms, but no impedance data from healthy preterm neonates have been available to determine whether those symptomatic neonates had an increased number of weakly acidic reflux episodes or increased reactivity to a physiologic number of reflux events. Our aim with this study was to provide impedance-pH values for acid, weakly acidic, and weakly alkaline reflux from healthy preterm neonates.

METHODS

Esophageal impedance was recorded for 24 hours in 21 asymptomatic preterm neonates by replacing the conventional feeding tube with a specially designed feeding tube that included 9 impedance electrodes (8 French). All neonates were asymptomatic, with spontaneous breathing. Reflux monitoring was performed after comprehensive explanation and on receipt of written parental consent. Esophageal and gastric pH were monitored using a separate parallel pediatric catheter (6 French). According to the corresponding pH change, impedance-detected reflux was classified as acid, weakly acidic, and weakly alkaline. For each infant, the total number of reflux events, the acid exposure and bolus exposure times at 2 cm above the respiratory inversion point, and average proximal extent of reflux were calculated.

RESULTS

Twenty-six preterm neonates were recruited into this study. A preliminary analysis was performed, and tracings were classified according to their quality and the presence of technical artifacts (spontaneous pH and impedance drifts, esophageal probe migration, and dysfunction of 1 or more impedance channels). Five studies were excluded because of 1 or more technical artifacts; a total of 21 neonates represent the final cohort included. At birth, the infants had a median postmenstrual age of 32 weeks, and the measurements were performed at a median age of 12 days. The total recording time was 23.7 +/- 2 hours. Gastric pH was higher than 4 during 69.3 +/- 20.4% of the recording time. The median number of reflux events in 24 hours was 71, 25.4% (range: 0%-53.1%) of which were acid, 72.9% (range: 45.3%-98.0%) were weakly acidic, and 0% (range: 0%-8.1%) were weakly alkaline. Compared with fasting periods, feeding periods tended to be associated with a higher number of total reflux events per hour. The acidity of reflux, however, was significantly different: during fasting, the number of acid reflux episodes per hour was higher, whereas during feeding, the number of weakly acidic reflux episodes was increased. Most reflux events were only liquid, whereas gas was present either mixed with liquid or pure only in 7.7% of all reflux episodes detected. The proximal esophageal segments were reached in 90% of reflux episodes. Reflux-related acid exposure (pH drops associated with impedance-detected reflux) was 1.66% (range: 0%-6.43%), whereas total acid exposure (associated and not associated with reflux detected by impedance) was 5.59% (range: 0.04%-20.69%). There was no relationship between the number or acidity of reflux events and anthropometric parameters such as weight and gestational age.

CONCLUSIONS

We present the first study using 24-hour impedance-pH recordings in asymptomatic premature neonates. Previous studies that used pH-metry suggested that neonatal cardiorespiratory symptoms could be related to acid gastroesophageal reflux. However, pH-metry could not detect accurately weakly acidic or nonacid reflux. Our healthy premature neonates had approximately 70 reflux events in 24 hours, 25% of which were acid, 73% were weakly acidic, and 2% were weakly alkaline. The number of reflux events per hour (2-3 per hour) was slightly lower than that described in premature neonates with cardiorespiratory events (4 per hour). We confirmed that weakly acidic reflux is more prevalent than acid reflux, particularly so during the feeding periods. In contrast, similar to healthy adults, weakly alkaline reflux was very rare. We confirmed findings from previous studies in which most reflux events were pure liquid during both fasting and during postprandial periods and gas reflux was very rare. As in neonates with cardiorespiratory symptoms, the majority of reflux events in asymptomatic preterms reached the proximal esophagus or pharynx, and there were no differences between acid and weakly acidic reflux. The lack of differences between asymptomatic and diseased infants contravenes the hypothesis for macro- or microaspiration but does not exclude hypersensitivity to reflux as a cause for respiratory symptoms. The acid exposure that was related to reflux events and detected by impedance was significantly lower than the total acid exposure during 24 hours. Increased acid exposure could be attributable to pH-only reflux events or, less frequently, to slow drifts of pH from baselines at approximately 5 to values < 4. These changes were not accompanied by a typical impedance pattern of reflux but by slow drifts in impedance in 1 or 2 channels. Our findings confirm the need for the use of impedance together with pH-metry for diagnosis of all gastroesophageal reflux events. The relationship between gastroesophageal reflux and cardiorespiratory events in neonates and older infants has been studied extensively. The current evidence for such a relationship is controversial. This study provides values of impedance-pH monitoring for acid, weakly acidic, and weakly alkaline reflux from healthy preterm neonates that can be used for comparison when evaluating gastroesophageal reflux in preterm infants with a cardiorespiratory disease.

Starch thickening of human milk is ineffective in reducing the gastroesophageal reflux in preterm infants: a crossover study using intraluminal impedance

We evaluated the efficacy of the thickening of human milk by precooked starch in reducing gastroesophageal reflux in preterm infants. Five preterm infants with frequent regurgitations (median gestational age, 28 weeks; range, 27 to 32 weeks; median birth weight, 990 g; range, 570 to 1900 g) were fed alternately during 24 hours with four meals of fortified maternal milk (milk A) and four meals of fortified maternal milk thickened by 1.5 g of precooked starch per 100 mL of milk (milk B). The acidic and buffered refluxes were detected by simultaneous pH monitoring and multiple intraluminal impedance. Eight feeding periods for each baby were recorded. The number of the acidic (34 after milk A vs 36 after milk B) and buffered (112 after milk A vs 134 after milk B) episodes of gastroesophageal reflux did not differ. Thickening human milk by precooked starch is ineffective in reducing gastroesophageal reflux in premature infants.

Apnea is not prolonged by acid gastroesophageal reflux in preterm infants

OBJECTIVE

To examine the temporal relationship between apnea and gastroesophageal reflux (GER) and to assess the effect of GER on apnea duration.

METHODS

A total of 119 preterm infants underwent 12-hour cardiorespiratory monitoring studies using respiratory inductance plethysmography, heart rate, oxygen saturation (SaO2), and esophageal pH. The studies were scored for GER (pH <4 for > or =5 seconds) and apnea > or =15 seconds or > or =10 seconds that occurred within 30 seconds of GER. Apnea > or =10 seconds was used to assess whether GER would prolong apnea duration.

RESULTS

There were 6255 episodes of GER. Only 1% of GER episodes were associated with apnea > or =15 seconds, and there was no difference in apnea rate before, during, or after GER. There was also no difference in rate of apnea > or =10 seconds before versus during GER; however, there was a decrease in apnea rate immediately after GER. The presence of GER during apnea did not prolong apnea duration, and GER had no effect on the lowest SaO2 or heart rate during apnea.

CONCLUSION

There is no evidence of a temporal relationship between acid-based GER and apnea in preterm infants. In addition, GER does not prolong apnea duration and does not exacerbate the resultant decrease in heart rate and SaO2.

Evidence-based neonatal care

Randomized controlled trials were introduced into neonatal care in the 1950s when high inspired oxygen concentrations were discovered to be the cause of an epidemic of blindness in preterm babies due to retinopathy of prematurity. Systematic reviews of many randomized controlled trials were published in an important textbook in 1992, 'Effective Care of the Newborn Infant', which was the starting point for the Neonatal Module of the Cochrane Collaboration. The 171 systematic reviews of interventions in neonatology published in the Cochrane Library provide evidence for neonatal care in many areas of the speciality. Some areas, such as management of respiratory distress with surfactant and assisted ventilation, are well covered by reviews, but others, such as resuscitation at birth and management of jaundice, are much less evidence based. Most of the systematic reviews deal with neonatal care in the developed world, and there are only a few of interest to carers in the developing world.

[The influence of the supine and prone positions in the esophageal pH monitoring in very low birth weight infants]

BACKGROUND

Scarce information is available on the effects of body's positioning in the number and the duration of gastroesophageal reflux episodes in very low birth weight infants.

AIM

To evaluate the influence of prone compared to supine positions on the frequency and duration of acid gastroesophageal reflux episodes in very low birth weight infants and study the role of body position in the occurrence of exams with reflux index > or = 5% and > or = 10%.

METHODS

Sixty one prolonged esophageal pH monitoring exams were retrospectively analyzed. The difference between the prone and supine position exam duration was not longer than 3 hours. The reflux index was evaluated for the total period of the exam (reflux index total) and for each period in the two positions. The total number of reflux episodes, the number of reflux episodes > 5 minutes and the longest reflux episode were evaluated for each period in the two positions. These parameters were compared in accordance with body positioning, for each one of the three reflux index total categories: reflux index total < 5%, > or = 5% and > or = 10%. The frequencies of exams with reflux index total > or = 5% and reflux index total > or = 10% were compared for both positions.

RESULTS

The number of hours in prone (11.2 +/- 1.0) and in supine (11.2 +/- 1.1) position were not different. All the prone positions monitoring parameters were significantly lower than the supine ones, in the three reflux index total categories. In the supine position, 32.7% (20/61) and 27.8% (17/61) of the exams, which were normal in prone, became abnormal, taking into account reflux index > or = 5% and > or = 10%, respectively, obtained for each position.

CONCLUSIONS

In prone position, there is a significant decrease in number and duration of acid reflux episodes in very low birth weight infants. Supine position promotes a significant increase in the number of esophageal pH monitoring exams with reflux index > or = 5% and > or = 10%, making easier the diagnose of the gastroesophageal reflux disease.

Discerning differences: gastroesophageal reflux and gastroesophageal reflux disease in infants

Gastroesophageal reflux (GER) is a frequently encountered problem in infancy; it commonly resolves spontaneously by 12 months of age. Caregivers are challenged to discriminate between physiologic GER and the much less common and more serious condition of pathologic gastroesophageal reflux disease (GERD). Pathologic GERD may require more extensive clinical evaluation and necessitate treatment. GERD may be primary or secondary; secondary GERD is associated with a number of genetic syndromes, chromosomal abnormalities, birth defects, or a host of neurologic conditions frequently seen in the newborn intensive care unit. This article reviews the unique anatomic, physiologic, developmental, and nutritional vulnerabilities of infants that make them susceptible to GER and GERD. The North American Society of Pediatric Gastroenterology and Nutrition have recently developed a comprehensive evidence-based clinical practice guideline that structures the diagnostic approach and treatment option in infants with suspected and confirmed GERD. These guidelines provide clear definitions of GER and GERD to aid the clinician in distinguishing between the 2 conditions. They emphasize the use of history and physical examination and discuss the indications for the use of other diagnostic procedures, such as upper gastrointestinal studies, nuclear medicine scintiscan, esophagogastroduodenoscopy with biopsy, and esophageal pH probe monitoring. Management of GERD begins with a nonpharmacologic approach; the emphasis is on positioning, a trial of a hypoallergenic formula, and thickening of feedings. When these measures fail to control symptoms, a trial of either histamine(2) antagonists or a proton pump inhibitor may be indicated. Finally, surgical treatment may be needed if all other management measures fail. New sleep recommendations for infants with GERD are now consistent with the American Academy of Pediatrics' standard recommendations. Prone sleep positioning is only considered in unusual cases, where the risk of death and complications from GERD outweighs the potential increased risk of sudden infant death syndrome (SIDS). The nursing care of infants with GER and GERD, as well as relevant issues for parent education and support, are reviewed and are essential elements in managing this common condition.

Gastroesophageal reflux: a critical review of its role in preterm infants

There is widespread concern about gastroesophageal reflux (GER) in preterm infants. This article reviews the evidence for this concern. GER is common in infants, which is related to their large fluid intake (corresponding to 14 L/day in an adult) and supine body position, resulting in the gastroesophageal junction's being constantly "under water." pH monitoring, the standard for reflux detection, is of limited use in preterm infants whose gastric pH is >4 for 90% of the time. New methods such as the multiple intraluminal impedance technique and micromanometric catheters may be promising alternatives but require careful evaluation before applying them to clinical practice. A critical review of the evidence for potential sequelae of GER in preterm infants shows that 1) apnea is unrelated to GER in most infants, 2) failure to thrive practically does not occur with GER, and 3) a relationship between GER and chronic airway problems has not yet been confirmed in preterm infants. Thus, there is currently insufficient evidence to justify the apparently widespread practice of treating GER in infants with symptoms such as recurrent apnea or regurgitation or of prolonging their hospital stay, unless there is unequivocal evidence of complications, eg, recurrent aspiration or cyanosis during vomiting. Objective criteria that help to identify those presumably few infants who do require treatment for GER disease are urgently needed.

Anti-reflux surgery for the neonatal intensive care-dependent infant

AIM

The benefit of anti-reflux surgery for gastro-oesophageal reflux (GOR) in early infancy is uncertain. The aim of this study was to assess the value of Nissen fundoplication in a group of infants with severe GOR.

METHODS

10 infants underwent Nissen fundoplication for gastro-oesophageal reflux following a failure of medical management. All had suffered life-threatening respiratory episodes as a consequence of gastro-oesophageal reflux, and were neonatal intensive care-dependent. Median (range) birth weight was 1.26 kg (0.48-3.8 kg), gestation 30 weeks (25-38 weeks); at surgery, weight was 3.25 kg (2.5-6.1 kg) at a corrected age of 11.5 weeks (term-22) weeks. For each infant, the success of enteral feeding and the level of support required pre- and post-operatively was compared, and where appropriate, the facilitation of palliative feeding was assessed. Median follow-up was 14 (3-36) months.

RESULTS

No infant suffered intra-operative morbidity or mortality. One infant died within 1 month of surgery from a collapse unrelated to surgery. Eight of nine surviving infants were discharged from intensive care following extubation and the establishment of enteral feeding. One patient died of severe bronchopulmonary dysplasia 3 months post-surgery. One infant developed a gastrostomy site infection, and two required gastrostomy tube replacement within 6 months of surgery. All were thriving at follow-up. Two infants with a congenital myopathy died as a result of their muscle disease at 9 and 11 months post-operatively.

CONCLUSIONS

Nissen fundoplication is a feasible, effective and safe operation in severe gastro-oesophageal reflux unresponsive to medical treatment in term and pre-term infants. It has an additional important role in facilitating safe palliative enteral feeding in infants with a diagnosis incompatible with survival into adulthood.

Multipoint measurement of intragastric pH in healthy preterm infants

BACKGROUND

The diagnostic use of 24 hour oesophageal pH monitoring in infants is controversial because of the impact of feed buffering of gastric acidity.

AIM

To re-evaluate the effect of feeding on gastric pH and reflux using multipoint pH measurements.

SUBJECTS

Fifteen healthy premature infants fed every four hours.

METHODS

Oesophageal pH and intragastric pH at 3, 6, and 9 cm below the lower oesophageal sphincter were simultaneously measured using a four channel pH probe for four hours after bolus feeding. Parameters of pH were compared for the different levels within the stomach. During reflux episodes, the nadir pH was compared with intragastric pH at all levels.

RESULTS

The proximal stomach was more significantly buffered by feeding and slower to re-acidify postprandially than the mid and distal stomach (42.2% of the time at pH < 4 compared with 58.7% and 55.7% respectively). During 27 of 62 gastro-oesophageal reflux episodes, nadir oesophageal pH was lower than the pH of the proximal stomach but always equal to or higher than the pH of the distal stomach.

CONCLUSIONS

These data indicate that previous studies may have overestimated the effect of feeding on gastric acidity and reflux.

The mismatch between evidence and practice. Common therapies in search of evidence

Many therapies in neonatology persist without supportive evidence: some common therapies may actually be harmful. Evidence-based medicine is the "conscientious, explicit and judicious use of current best evidence in making decisions about the care of individual patients". The best available evidence, however, is not always sound or valid evidence. Sometimes, when faced with a collection of reports that do not constitute good evidence, attempts to choose the best evidence become pointless; in this case, a statement of no good evidence is preferable. There is a continuing problem with the place of usual practice in the hierarchy of evidence; usual practice generates experience with a particular practice but no reliable information regarding how the practice compares with alternative strategies. Although clinical and institutional inertia combined with a litigious practice environment tend to uphold current practice, the field of neonatology is ripe with examples of established therapies that were subsequently shown to be harmful. It is important to focus on important long-term outcomes and as much on the possibility of harm as on the chance of benefit, especially for new therapies, before they become routine practice. In the face of inadequate evidence, it is particularly important to avoid the temptation to institute treatment guidelines that inhibit further research. Patients are better served by guidelines that recommend only strategies that are supported by strong evidence and recommend further research when the evidence is inadequate.

Congenital H-type fistula: delayed diagnosis in a preterm infant

H-type tracheoesophageal fistula is a rare congenital condition. Its rarity and concurrent problems, such as respiratory distress, may delay its detection. We report delay in the diagnosis in a preterm small-for-gestational-age baby who showed symptoms of apnea and recurrent pneumonia, even when she was being fed by orogastric tube.

Detection of small bolus volumes using multiple intraluminal impedance in preterm infants

BACKGROUND

Multiple intraluminal impedance (MII) is a new technique that allows detection of reflux and swallows via changes in impedance caused by a liquid bolus inside the esophagus. The method is independent of pH. The authors studied the ability of this technique to detect the small bolus volumes potentially occurring in young infants.

METHODS

Ten preterm infants (median gestational age at birth, 33 weeks; range, 25-36 weeks; age at study, 9 days; range, 2-39 days) underwent 10 instillations each of 0.1 mL to 0.5 mL saline while MII was recorded via a 2.4-mm nasogastric catheter. MII signals were analyzed for swallows, defined as a decrease in impedance starting within 1 minute. From the liquid instillation in the most proximal channel and extending downward, impedance changes during these induced swallows were compared with those occurring during spontaneous swallows.

RESULTS

All 100 liquid instillations resulted in a typical impedance pattern, occurring after a median interval of 4.4 seconds (range, 1.8-8.9 seconds). The decrease in impedance was more pronounced than after spontaneous swallows (30% vs. 24%, P < 0.03) and extended downward more rapidly (12.3 cm/s vs. 5.8 cm/s, P < 0.01).

CONCLUSION

Bolus transport of small liquid volumes can be detected via MII.