Esophageal Function and Reflux Evaluations in Lung Transplantation: A Nationwide Survey of UNOS-Accredited Transplant Centers in the United States

INTRODUCTION

Gastroesophageal reflux disease has been associated with worse lung transplant outcomes. We aimed to assess local practices for esophageal function testing (EFT) across transplant centers.

METHODS

This was a survey study of all United Network for Organ Sharing-accredited adult lung transplant centers regarding local EFT practice.

RESULTS

Among 39/63 (60%) responded centers, 38.5% required any EFT (35.9% esophageal manometry, 15.4% pH monitoring, and 28.2% pH impedance), while another 28.2% may consider EFT based on symptoms. Five-year transplant volume was higher among centers requiring EFT (253 vs 159, P = 0.04).

DISCUSSION

Only a minority of lung transplant centers routinely obtained EFT, supporting the need for guidelines for standardized reflux/esophageal assessment.

British Society of Gastroenterology guidelines for oesophageal manometry and oesophageal reflux monitoring

These guidelines on oesophageal manometry and gastro-oesophageal reflux monitoring supersede those produced in 2006. Since 2006 there have been significant technological advances, in particular, the development of high resolution manometry (HRM) and oesophageal impedance monitoring. The guidelines were developed by a guideline development group of patients and representatives of all the relevant professional groups using the Appraisal of Guidelines for Research and Evaluation (AGREE II) tool. A systematic literature search was performed and the GRADE (Grading of Recommendations Assessment, Development and Evaluation) tool was used to evaluate the quality of evidence and decide on the strength of the recommendations made. Key strong recommendations are made regarding the benefit of: (i) HRM over standard manometry in the investigation of dysphagia and, in particular, in characterising achalasia, (ii) adjunctive testing with larger volumes of water or solids during HRM, (iii) oesophageal manometry prior to antireflux surgery, (iv) pH/impedance monitoring in patients with reflux symptoms not responding to high dose proton pump inhibitors and (v) pH monitoring in all patients with reflux symptoms responsive to proton pump inhibitors in whom surgery is planned, but combined pH/impedance monitoring in those not responsive to proton pump inhibitors in whom surgery is planned. This work has been endorsed by the Clinical Services and Standards Committee of the British Society of Gastroenterology (BSG) under the auspices of the oesophageal section of the BSG.

Diagnostic accuracy of a pH stick, modified to detect gastric lipase, to confirm the correct placement of nasogastric tubes

Objective

The correct placement of a nasogastric feeding tube is usually confirmed by establishing that an aspirate is acidic using a pH stick. However, antacid medication and achlorhydria can cause false negative pH tests that may delay feeding and increase resource use. The purpose of this study was to evaluate a modified pH stick designed to detect gastric lipase and therefore reduce false negative tests.

Methods

In this prospective observational study, a convenience sample of adult patients who had either gastric and oesophageal samples taken during routine diagnostic gastroscopy (n=97) or bronchial and saliva samples taken during a bronchoscopy (n=106). The samples were tested by blinded observers using the modified and standard pH sticks. The sensitivities and specificities of the two pH sticks in identifying gastric and non-gastric aspirates were compared using the pH cut-off ≤5.5.

Results

The sensitivities of a pH≤5.5 to correctly identify gastric samples were 66% (95% CI 56 to 75) and 68% (95% CI 57 to 77) for the modified and the standard pH, respectively. The specificities were 81% (95% CI 76 to 85) and 79% (95% CI 74 to 84). There were no significant differences in the distribution of the discordant results between the paired gastric and non-gastric samples for both the modified and standard pH sticks at pH≤5.5 (both McNemar’s tests, p≥0.05).

Conclusions

There were no significant differences between the paired modified and standard pH tests for the gastric samples. Due to the limited accuracy of pH sticks, further research is required to identify accurate and cost-effective bedside methods to confirm the correct placement of nasogastric tubes.

Selecting pH cut-offs for the safe verification of nasogastric feeding tube placement: a decision analytical modelling approach

OBJECTIVES

The existing British National Patient Safety Agency (NPSA) safety guideline recommends testing the pH of nasogastric (NG) tube aspirates. Feeding is considered safe if a pH of 5.5 or lower has been observed; otherwise chest X-rays are recommended. Our previous research found that at 5.5, the pH test lacks sensitivity towards oesophageal placements, a major risk identified by feeding experts. The aim of this research is to use a decision analytic modelling approach to systematically assess the safety of the pH test under cut-offs 1-9.

MATERIALS AND METHODS

We mapped out the care pathway according to the existing safety guideline where the pH test is used as a first-line test, followed by chest x-rays. Decision outcomes were scored on a 0-100 scale in terms of safety. Sensitivities and specificities of the pH test at each cut-off were extracted from our previous research. Aggregating outcome scores and probabilities resulted in weighted scores which enabled an analysis of the relative safety of the checking procedure under various pH cut-offs.

RESULTS

The pH test was the safest under cut-off 5 when there was ≥30% of NG tube misplacements. Under cut-off 5, respiratory feeding was excluded; oesophageal feeding was kept to a minimum to balance the need of chest X-rays for patients with a pH higher than 5. Routine chest X-rays were less safe than the pH test while to feed all without safety checks was the most risky.

DISCUSSION

The safety of the current checking procedure is sensitive to the choice of pH cut-offs, the impact of feeding delays, the accuracy of the pH in the oesophagus, as well as the extent of tube misplacements.

CONCLUSIONS

The pH test with 5 as the cut-off was the safest overall. It is important to understand the local clinical environment so that appropriate choice of pH cut-offs can be made to maximise safety and to minimise the use of chest X-rays.

TRIAL REGISTRATION NUMBER

ISRCTN11170249; Pre-results.

The effect of antisecretory therapy and study duration on ambulatory esophageal pH monitoring

BACKGROUND

Conventional catheter-based and wireless pH monitoring continue to be widely used for the evaluation of GERD symptoms despite the emergence of pH-impedance monitoring.

GOALS

We sought to identify patient- and test-related factors predicting objective GERD parameters on catheter-based and wireless pH monitoring.

STUDY

Ambulatory pH studies in 2,067 subjects (50.4 ± 0.3 years, 66.3% female) were assessed for presenting symptoms, antireflux therapy status, test characteristics, distal esophageal total acid exposure time (AET), symptom index (SI), and symptom-reflux association (Ghillebert probability estimate, GPE). Univariate and multivariate logistic regression analyses were performed to identify predictors of GERD evidence, both off and on antireflux therapy.

RESULTS

Catheter-based pH monitoring was performed in 77.6%, and 90.1% of the studies were performed off antireflux therapy. The likelihood of finding GERD evidence was significantly higher off therapy (65.8 vs. 21.4% on therapy, p < 0.0001); this held true for both strong GERD evidence (elevated AET and positive GPE) and elevated AET alone. The SI did not complement AET and GPE. Extended pH recording with the wireless technique consistently increased diagnostic yield. On multivariate logistic regression, the status of antireflux therapy and frequency of symptoms dictated finding of GERD evidence, and yields were highest for perceptive symptoms (heartburn, chest pain, and cough).

CONCLUSIONS

Ambulatory pH testing off antireflux therapy improves detection of all degrees of GERD evidence. pH testing provides highest yields with frequent perceptive symptoms and least with isolated regurgitation and ENT symptoms. Extending pH-recording with wireless monitoring uniformly augments yield.

Lipid-laden macrophage index is not an indicator of gastroesophageal reflux-related respiratory disease in children

BACKGROUND

The lipid-laden macrophage index has been used to evaluate for gastroesophageal reflux-related respiratory disease, but the relationship between reflux detected by pH probe and the lipid-laden macrophage index is uncertain despite widespread use of the lipid-laden macrophage index in clinical decision-making. It was the aim of this study to correlate reflux as detected by multichannel intraluminal impedance with the lipid-laden macrophage index.

METHODS

Patients undergoing both pH multichannel intraluminal impedance testing and bronchoscopy between January 2002 and January 2006 were identified. Baseline characteristics were compared by using parametric and nonparametric testing. Reflux profiles were correlated with the lipid-laden macrophage index by using Spearman correlations.

RESULTS

There was no significant correlation between the lipid-laden macrophage index and the number of acid or nonacid reflux events. There also was no significant correlation between the lipid-laden macrophage index and the amount of full-column reflux. There was no significant difference between the mean lipid-laden macrophage index in patients with and without esophagitis. Finally, in patients who underwent fundoplication (n = 13) for intractable respiratory disease, there was no significant difference in any of the reflux parameters between patients who did and did not experience clinical improvement after fundoplication. There was, however, a higher lipid-laden macrophage index in patients with no symptomatic improvement compared with patients with symptomatic improvement.

CONCLUSIONS

Lipid-laden macrophage index lacks the specificity necessary to detect reflux-related respiratory disease.

Determinants of perception of heartburn and regurgitation

BACKGROUND AND AIMS

It is not known why some reflux episodes evoke symptoms and others do not. We investigated the determinants of perception of gastro-oesophageal reflux.

METHODS

In 32 patients with symptoms suggestive of gastro-oesophageal reflux, 24 hour ambulatory pH and impedance monitoring was performed after cessation of acid suppressive therapy. In the 20 patients who had at least one symptomatic reflux episode, characteristics of symptomatic and asymptomatic reflux episodes were compared.

RESULTS

A total of 1807 reflux episodes were detected, 203 of which were symptomatic. Compared with asymptomatic episodes, symptomatic episodes were associated with a larger pH drop (p<0.001), lower nadir pH (p<0.05), and higher proximal extent (p<0.005). Symptomatic reflux episodes had a longer volume and acid clearance time (p<0.05 and p<0.002). Symptomatic episodes were preceded by a higher oesophageal cumulative acid exposure time (p<0.05). The proximal extent of episodes preceding regurgitation was larger than those preceding heartburn; 14.8% of the symptomatic reflux episodes were weakly acidic. In total, 426 pure gas reflux episodes occurred, of which 12 were symptomatic. Symptomatic pure gas reflux was more frequently accompanied by a pH drop than asymptomatic gas reflux (p<0.05).

CONCLUSIONS

Heartburn and regurgitation are more likely to be evoked when the pH drop is large, proximal extent of the refluxate is high, and volume and acid clearance is delayed. Sensitisation of the oesophagus occurs by preceding acid exposure. Weakly acidic reflux is responsible for only a minority of symptoms in patients off therapy. Pure gas reflux associated with a pH drop ("acid vapour") can be perceived as heartburn and regurgitation.

Acid reflux event detection using the Bravo wireless versus the Slimline catheter pH systems: why are the numbers so different?

OBJECTIVE

This study analysed the relative accuracy of the Bravo wireless and the Slimline catheter-Mark III Digitrapper pH systems in the detection of acid reflux events.

METHODS

Twenty five asymptomatic subjects were studied. A Bravo capsule was placed 6 cm above the squamocolumnar junction (SCJ), marked by an endoclip, and a Slimline pH catheter was placed 5 cm above the manometrically localised lower oesophageal sphincter. The distance between the SCJ and each pH electrode was measured fluoroscopically. An in vivo pH reference was established using swallows of orange juice (pH 3.88). Concurrent pH data from the two systems were analysed in Excel spreadsheets.

RESULTS

Significantly more acid reflux events were reported by the Digitrapper system than the Bravo system (117.0 v 41.8). This was not explained by electrode position as there was no difference in median distance between the SCJ and either pH electrode (7.25 cm v 7.08 cm). The dominant source of discrepancy between systems was inaccuracy in electrode calibration and, after adjustment using the in vivo orange juice pH measurement, the discrepancy improved by 40%. However, discrepancy still existed and was most pronounced with short reflux events (1-15 s for the catheter, 1-17 s for the Bravo) associated with minimal intraoesophageal acidity and poor concordance between systems.

CONCLUSION

Substantially more reflux events were reported by the Digitrapper system compared with the Bravo system; 40% of excess events were attributable to a flawed software scheme for electrode thermal calibration while most of the remainder were brief events with poor reproducibility between systems.

Simultaneous recordings of oesophageal acid exposure with conventional pH monitoring and a wireless system (Bravo)

OBJECTIVES

Oesophageal pH monitoring is a useful test for the diagnosis of gastro-oesophageal reflux disease (GORD) but has some limitations related to the nasopharyngeal electrode. Recently, a telemetric catheter free system (CFS) (Bravo; Medtronic) was developed. The aim of this study was to determine the concordance of data between the conventional pH measurement system (CPHMS) and the CFS Bravo.

METHODS

Forty patients with symptoms suggestive of GORD underwent 24 hour oesophageal pH monitoring using the CPHMS with a nasopharyngeal electrode and the Bravo CFS simultaneously. The sensitive tips of both electrodes were positioned at the same level under fluoroscopy. In addition to automatic analysis, each reflux episode was checked visually and characterised.

RESULTS

There was a significant correlation (r = 0.87, p < 0.0001) between the 24 hour oesophageal acid exposures recorded by the CPHMS and the CFS. Twenty four hour oesophageal acid exposure was significantly lower with the CFS than with the CPHMS (2.4 (0.4-8.7) v 3.6 (0.7-8.6); p < 0.0001). Consequently, with the CFS, the cut off level for the diagnosis of GORD, as calculated from the regression equation, was 2.9% (for the 4.2% cut off determined in controls with the CPHMS). After this adjustment, concordance of the diagnosis of GORD was 88% (kappa 0.760). Diagnosis of GORD was established in more patients with the CFS 48 hour results than with the 24 hour results.

CONCLUSIONS

Despite strong correlations between oesophageal acid exposure recorded with the two devices, the Bravo CFS significantly under recorded acid exposure compared with the CPHMS. Provided some correcting factors are used, the Bravo CFS can improve the sensitivity of pHmetry for the diagnosis of GORD by allowing more prolonged recordings.

Prevalence of acid reflux in functional dyspepsia and its association with symptom profile

AIM

A subset of functional dyspepsia patients respond to acid suppressive therapy, but the prevalence of non-erosive reflux disease in functional dyspepsia and its relevance to symptoms have never been established. The aim of the present study was to study 24 hour pH monitoring in consecutive functional dyspepsia patients.

METHODS

A total of 247 patients with dyspeptic symptoms (166 women, mean age 44 (SEM 1) year), with a negative upper gastrointestinal endoscopy and without dominant symptoms of heartburn participated in the study. In all patients, the severity of dyspeptic symptoms and the presence of heartburn was assessed by a questionnaire and a 24 hour oesophageal pH monitoring study was performed. All patients underwent a gastric emptying breath test and in 113 a gastric barostat study was performed.

RESULTS

Abnormal pH monitoring (acid exposure >5% of time) was found in 58 patients (23%). Of 21 patients with a positive heartburn questionnaire, 76% had pathological pH monitoring, while this was the case in only 18.5% of patients with a negative heartburn questionnaire. Demographic characteristics and the prevalence of other pathophysiological mechanisms did not differ between heartburn negative patients with normal or abnormal acid exposure. Pathological acid exposure in heartburn negative patients was associated with the presence of epigastric pain (65 v 84%, p<0.005) and of moderate or severe pain (48 v 69%, p = 0.005).

CONCLUSION

Pathological oesophageal acid exposure is only present in a subset of heartburn negative functional dyspepsia patients, which are characterised by a higher prevalence of epigastric pain.

Oesophageal clearance of acid and bile: a combined radionuclide, pH, and Bilitec study

BACKGROUND

Studies combining pH and Bilitec monitoring found a high prevalence of both acid and duodeno-gastro-oesophageal reflux in severe reflux disease. Clearance of refluxed material is a major defence mechanism against reflux. Several studies have been devoted to oesophageal acid clearance but oesophageal clearance of refluxed duodenal contents (DC) has rarely been addressed.

AIM

To compare oesophageal acid and DC clearance.

METHODS

Ten healthy volunteers (five women, mean age 23 (1) years) were studied. Firstly, a balloon tip catheter, positioned in the duodenum under fluoroscopy, was used to aspirate DC after stimulation by a high caloric liquid meal (200 ml, 300 kcal). During the second session, pH and Bilitec probes were positioned 5 cm above the lower oesophageal sphincter and a small infusion catheter was introduced into the proximal oesophagus. The subject was placed supine under a gamma camera. One of two different solutions (DC mixed with 0.2 mCi Tc99m pertechnetate or citric acid (pH 2) mixed with 0.2 mCi Tc99m pertechnetate) was infused into the proximal oesophagus and the subject was instructed to swallow at 20 second intervals. Clearance was assessed using scintigraphy (dynamic acquisition, one frame per second in the anterior view; calculation of time to clear peak counts to background level), pH (time to pH<4) or Bilitec (time absorbance >0.14) monitoring, with or without continuous saliva aspiration. Each condition was studied twice in a randomised design; measurement time was four minutes, interrupted by water flushing, with a two minute rest period. Results are given as mean (SEM) and were compared by Student's t test and Pearson correlation.

RESULTS

Scintigraphic evaluation showed a volume clearance time of 29 (3) seconds for acid and 28 (9) seconds for DC (NS). Saliva aspiration had no significant influence on volume clearance of acid or DC (28 (4) and 30 (13) seconds, respectively; NS). pH monitoring showed an acid clearance time of 217 (15) seconds, which was significantly prolonged to 324 (30) seconds during saliva aspiration (p<0.05). Bilitec monitoring showed a DC clearance time of 131 (27) seconds, which was not significantly prolonged by saliva aspiration (176 (36) seconds; p = 0.08). DC clearance was faster than acid clearance, either without or with saliva aspiration (p<0.055 and p<0.05, respectively).

CONCLUSIONS

Under experimental conditions, liquid acid and DC solutions have comparable volume clearances. Chemical clearance occurs slightly faster for DC than for acid, and saliva plays a major role in the clearance of acid only.

Acid secretion from a heterotopic gastric mucosa in the upper esophagus demonstrated by dual probe 24-hour ambulatory pH monitoring

Heterotopic gastric mucosa in the upper esophagus is frequently found during endoscopic examination. Although most patients with heterotopic gastric mucosa of the upper esophagus, referred as inlet patch, are asymptomatic, symptomatic patients with complications resulting from this ectopic mucosa have also been reported. Acid secretion by the inlet patch has been suggested in some reports. We report a case of heterotopic gastric mucosa in the upper esophagus, with secretion of acid, demonstrated by continuous ambulatory pH monitoring, and the improvement of pharyngeal symptoms after the use of a proton pump inhibitor.