Search PubMed⌕ Search

Biomedical subjects

P J Kahrilas

Publications and source records attributed to P J Kahrilas.

At least 19 recordsLinked to original sources
PubMed2006

Slimline vs. glass pH electrodes: what degree of accuracy should we expect?

BACKGROUND: Ambulatory pH monitoring is considered the gold standard for measuring oesophageal acid exposure, however, data comparing antimony and glass electrodes are limited. AIM: To compare the accuracy of the Slimline antimony pH monitoring system and a conventional glass electrode catheter pH monitoring system during ambulatory conditions. METHODS: Eighteen subjects (13 males, 23-45 years) underwent simultaneous pH monitoring using the Slimline antimony pH electrode and MIC M3 glass pH electrode pH monitoring systems for 12 h. Acid exposure was analysed and compared by manual extraction of the data onto an excel spreadsheet. RESULTS: There was no statistical difference in the median per cent time the pH was <4 recorded by the two systems (Slimline, 3%, Glass MIC M3, 2%, P = 0.77) and the correlation was excellent (r = 0.84). The difference in recorded reflux events was also not significantly different between the two systems, with the absolute difference being 23 events (s.d., 26). Point-by-point discrepancy was 28% (s.d., 18%), however, the agreement in terms of reflex events was excellent (Kappa value, 0.89, s.d., 0.09). CONCLUSION: Despite substantial point-by-point disagreement, the antimony Slimline pH catheter compares favourably to the Glass MIC M3 pH catheter in terms of measuring standard pH parameters.

Adult↗
PubMed2006

Comparison of esophageal acid exposure at 1 cm and 6 cm above the squamocolumnar junction using the Bravo pH monitoring system.

The aim of this study was to assess the quantitative differences of acid exposure at 1 cm and 6 cm above the squamocolumnar junction (SCJ) using two radiotelemetry pH capsules affixed to the esophageal mucosa. Ten normal subjects and 10 endoscopy-negative gastroesophageal reflux disease (GERD) patients without hiatus hernia (ages 20-54, 12 male) were studied for a 24-h period using the Bravo pH monitoring system. pH capsules were placed 1 cm and 6 cm above the SCJ. Interpretable data for at least 14 h was obtained in 18 of the 20 subjects (9 normal, 9 GERD). Two failures occurred secondary to early capsule dislodgement. Median esophageal acid exposure was significantly increased at 1 cm above the SCJ compared to 6 cm above the SCJ during the total, upright and postprandial time periods in both normal and GERD subjects. During a 2 h postprandial period the esophageal acid exposure was 8-fold greater in GERD subjects and 5-fold greater in normal subjects 1 cm above the SCJ compared to 6 cm above the SCJ. Confident measurement of esophageal acid exposure at a fixed position 1 cm above the SCJ is feasible with the Bravo system. Acid exposure was significantly higher 1 cm above the SCJ compared to 6 cm above the SCJ in both GERD patients and controls. These findings suggest that measurement of acid exposure 1 cm above the SCJ may improve accuracy of pH monitoring by detecting acid reflux events confined to the distal esophagus.

Adult↗
PubMed2005

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.

Adult↗
PubMed2005

Review article: oesophageal pH monitoring--technologies, interpretation and correlation with clinical outcomes.

Using a simple 'test' to diagnose gastro-oesophageal reflux disease is difficult because accurately measuring gastric refluxate and correlating reflux events with symptom episodes is complex. This paper reviews the safety, tolerability and diagnostic accuracy of Bravo (Medtronic, Shoreview, MN, USA), ambulatory oesophageal pH monitoring technology. Catheter-based pH electrodes inhibit patients' normal activity, and can yield erroneous results because of placement or subsequent migration of the probe or errors in the thermal compensation algorithm that is requisite for antimony pH electrodes. Bravo pH studies reliably discriminated oesophagitis patients from controls, but are less discriminatory in endoscopy-negative gastro-oesophageal reflux disease patients. The Bravo system can be accurately placed using endoscopic landmarks and pH studies demonstrated more accurate in vivo pH recording than with a catheter-based system. The Bravo system detected fewer reflux events of short duration compared with a catheter-based system. Studies examining the correlation between reflux events and symptoms have not yet been conducted using the Bravo system. In conclusion, the Bravo system offers a more user-friendly ambulatory pH monitoring technique that more accurately records pH compared with a catheter-based system. More research is needed to determine whether the detection of reflux events with Bravo will provide a good correlation with symptom episodes.

Esophageal pH Monitoring↗
PubMed2005

Measuring EGJ opening patterns using high resolution intraluminal impedance.

The aim of this study was to adapt impedance methodology to study esophagogastric junction (EGJ) sphincter opening and compare opening patterns of the EGJ during deglutitive LES relaxation (dLESR) and transient LES relaxation (tLESR). We studied eight healthy subjects with a novel 12-lumen combined impedance/manometry catheter, the main element of which was a 6 cm sleeve sensor with six side hole sensors and six impedance rings spaced at 1 cm increments along its length. Subjects underwent an air infusion protocol after standard assessment and data tracings and isocontour plots were analysed to assess opening characteristics of the EGJ during dLESRs and tLESRs. Our results revealed that during dLESR the opening pattern was top to bottom, occurred in 0-2.7 s and in 29 of 35 (83%) cases the leading edge of the bolus was liquid. Opening during tLESR began between -7.8 and +8.6 s relative to the onset of nadir LES relaxation. The opening pattern during tLESR was bottom to top, occurred in 0-7.7 s, and in 22 of 29 (76%) the leading edge was liquid. These results support that impedance monitoring can be adapted to identify sphincter opening, to distinguish sphincter opening from sphincter relaxation, and to determine luminal contents during the opening period.

Adult↗
PubMed2004

Review article: is stringent control of gastric pH useful and practical in GERD?

As the relative efficacy of therapeutic agents in the treatment of gastro-oesophageal reflux disease is related to how consistently and completely gastric acid secretion is suppressed, intragastric pH monitoring is a useful tool in stratifying therapies. If there is no acid in the stomach, there can be none to reflux into the oesophagus. Comparative crossover studies have shown consistently that once-daily esomeprazole (40 mg) provides more effective and longer lasting intragastric acid control than any other proton pump inhibitor currently available in healthy subjects and patients with gastro-oesophageal reflux disease. However, esomeprazole maintained intragastric pH > 4 for > or = 16 h in only about 55% of individuals tested. Thus, if more complete acid suppression is desirable, twice-daily proton pump inhibitor therapy may be advantageous. One such scenario is in patients with Barrett's metaplasia. Data from the ProGERD study suggest that, for each Los Angeles grade of oesophagitis, the healing rate for patients with Barrett's metaplasia is 10-30% less than that for non-Barrett's patients, being as low as 53% in patients with Los Angeles grade D oesophagitis. Also relevant to the Barrett's metaplasia population are studies on the oesophageal mucosa, which show that effective acid suppression favours differentiation and decreases epithelial cell proliferation. Both considerations argue for more intensive gastric acid inhibition than can be achieved with once-daily therapy, leading to experimentation with twice-daily proton pump inhibitor regimens. A randomized, double-blind, three-way crossover study compared esomeprazole 40 mg once daily with esomeprazole 20 mg and 40 mg twice daily and found that both twice-daily regimens were superior, maintaining intragastric pH > 4 for 73%[95% confidence interval (CI), 67-79%] and 80% (95% CI, 75-86%) of the day, respectively, compared with 59% (95% CI, 54-65%) of the day with esomeprazole 40 mg once daily, arguing that a twice-daily regimen may be the preferred strategy for patients with Barrett's metaplasia.

Anti-Ulcer Agents↗
PubMed2004

Review article: gastro-oesophageal reflux disease as a functional gastrointestinal disorder.

Gastro-oesophageal reflux disease encompasses a family of disorders united by a common pathogenesis: the excessive reflux of gastric contents. The best defined disorder is oesophagitis, but it is now evident that proton pump inhibitor therapy can resolve oesophagitis in virtually every case. The same cannot be said for gastro-oesophageal reflux disease symptoms, however, thus moving the frontier to symptom control. Endoscopy-negative reflux disease is a heterogeneous group, no longer bound by the common denominator of endoscopic findings. In fact, three distinct patient subgroups emerge: (i) individuals who in essence have oesophagitis, but are either in remission or simply fail to meet the endoscopic criteria; (ii) patients with hypersensitivity to oesophageal stimuli; and (iii) patients with 'functional heartburn' whose symptoms are not related to reflux. Given this heterogeneity, it is not surprising that the efficacy of antisecretory drugs is less impressive. This has led to new therapeutic approaches beyond acid control: mucosal protective agents, either central nervous system or peripherally acting compounds aimed at normalizing hyperalgesia, and reflux inhibitors and serotonergic agents, such as tegaserod.

Antacids↗
PubMed2004

Gastro-oesophageal reflux monitoring: review and consensus report on detection and definitions of acid, non-acid, and gas reflux.

To date, most concepts on the frequency of gastro-oesophageal reflux episodes and the efficiency of the antireflux barrier have been based on inferences derived from measurement of oesophageal pH. The development of intraluminal impedance monitoring has highlighted the fact that pH monitoring does not detect all gastro-oesophageal reflux events when little or no acid is present in the refluxate, even if special pH tracing analysis criteria are used. In November 2002, a workshop took place at which 11 specialists in the field of gastro-oesophageal reflux disease discussed and criticised all currently available techniques for measurement of reflux. Here, a summary of their conclusions and recommendations of how to achieve the best results from the various techniques now available for reflux measurement is presented.

Adult↗
PubMed2003

The effect of glucagon-induced gastric relaxation on TLOSR frequency.

This study aimed to determine the effect of glucagon-induced gastric relaxation on the frequency of transient lower oesophageal sphincter relaxations (TLOSRs). Eight normal subjects (four male, age 18-52 y) were studied after a 6-h fast using a combined manometric barostat assembly. The recording was divided into two 1-h sessions: (1) a baseline period with the barostat set at minimal distending pressure (MDP) + 2 mmHg and (2) a period with continuous glucagon or placebo infusion with barostat set at MDP + 2 mmHg. Patients were studied on two different days and randomly received glucagon (4.8 microg kg(-1) bolus followed by 9.6 microg kg(-1) h(-1) infusion) on 1 day and placebo (saline) on another. Lower oesophageal sphincter (LOS) pressure, frequency of TLOSRs, and barostat bag volumes were determined for both placebo and glucagon infusion. Glucagon induced significant fundal relaxation compared with placebo (P < 0.05) and significantly decreased baseline LEOS pressure (P < 0.05). The frequency of TLOSRs was not altered by glucagon infusion compared with placebo. Despite causing substantial proximal stomach relaxation, glucagon did not increase TLOSR frequency. This suggests that the relevant gastric mechanoreceptors responsible for triggering TLOSRs do not respond to passive elongation.

Adolescent↗
PubMed2003

Reduced tLESR elicitation in response to gastric distension in fundoplication patients.

Transient lower esophageal sphincter relaxations (tLESRs) are vagally mediated in response to gastric cardiac distension. Nine volunteers, eight gastroesophageal reflux disease (GERD) patients, and eight fundoplication patients were studied. Manometry with an assembly that included a barostat bag was done for 1 h with and 1 h without barostat distension to 8 mmHg. Recordings were scored for tLESRs and barostat bag volume. Fundoplication patients had fewer tLESRs (0.4 +/- 0.3/h) than either normal subjects (2.4 +/- 0.5/h) or GERD patients (2.0 +/- 0.3/h). The tLESRs rate increased significantly in normal subjects (5.8 +/- 0.9/h) and GERD patients (5.4 +/- 0.8/h) during distension but not in the fundoplication group. All groups exhibited similar gastric accommodation (change in volume/change in pressure) in response to distension. Fundoplication patients exhibit a lower tLESR rate at rest and a marked attenuation of the response to gastric distension compared with either controls or GERD patients. Gastric accommodation was not impaired with fundoplication. This suggests that the receptive field for triggering tLESRs is contained within a wider field for elicitation of gastric receptive relaxation and that only the first is affected by fundoplication.

Adult↗
PubMed2002

Distinct patterns of oesophageal shortening during primary peristalsis, secondary peristalsis and transient lower oesophageal sphincter relaxation.

This study characterized oesophageal shortening during secondary peristalsis and transient lower oesophageal sphincter relaxation (TLOSR) in an attempt to determine its contribution to the opening mechanism. Eight healthy subjects (four males, 26 +/- 1 years) had metal clips affixed at 0, +3, and +8 cm relative to the squamocolumnar junction (SCJ), defining two distal oesophageal segments. Axial clip movement was assessed with concurrent videofluoroscopy and manometry during primary peristalsis, secondary peristalsis and TLOSR. Clip-defined oesophageal segment length change was measured at 0.5-s intervals. The magnitude of the most distal segment shortening was least with TLOSR, greatest with primary peristalsis and intermediate with secondary peristalsis. Conversely, maximal overall oesophageal shortening during TLOSR, evidenced by SCJ movement, was similar to that during primary peristalsis. In 3/12 TLOSRs, the moment of LOS opening and gas reflux was optimally imaged; SCJ excursion was 0.3 +/- 0.1 cm prior to LOS opening and 1.4 +/- 0.7 cm immediately after gas reflux. The segmental pattern of oesophageal shortening was distinct during primary peristalsis, secondary peristalsis and TLOSR. During TLOSR, significant elevation of the SCJ occurred only after LOS opening, suggesting that this was a consequence of oesophageal distension induced by gas reflux rather than a component of the opening mechanism.

Adult↗
PubMed2002

Impaired egress rather than increased access: an important independent predictor of erosive oesophagitis.

Oesophagitis severity is related to total oesophageal acid exposure, which is in turn dependent upon both the number reflux events and the rate of refluxate clearance. This study examined differences in the frequency of reflux events and the characteristics of oesophageal acid exposure in asymptomatic controls and gastro-oesophageal reflux disease (GORD) patients both with and without oesophagitis. Nine controls and 38 patients with GORD were studied. All patients underwent upper endoscopy, videofluoroscopy, determination of resting lower oesophageal sphincter pressure (LOSP) and 24 h pH monitoring. Analysis was performed with subjects grouped as controls, non-erosive GORD and oesophagitis. A second analysis was performed with subjects grouped by hiatal hernia size. Statistical comparisons were made using anovaand unpairedt-tests. Patients with oesophagitis had significantly larger hiatal hernias, greater oesophageal acid exposure, more prolonged episodes of reflux and longer acid clearance times than did controls and patients with non-erosive GORD. No significant difference was seen in the number of reflux events. Increasing hiatal hernia size was significantly associated with increasing oesophageal acid exposure, number of prolonged reflux events and prolonged acid clearance times. Oesophagitis patients have significantly greater oesophageal acid exposure than subjects with non-erosive GORD. Increased oesophageal acid exposure in oesophagitis is attributable to impaired acid clearance and the greatest impairments in refluxate clearance occur in patients with large hiatal hernias.

Adult↗
PubMed2001

Supraesophageal complications of reflux disease and hiatal hernia.

A unifying theme of gastroesophageal reflux disease (GERD) is increased acid exposure on vulnerable epithelia. In most cases, the vulnerable epithelium is the esophagus, but alternatively it may be that of the supraesophageal terrain, which includes the larynx, pharynx, and airways. In 50% to 94% of patients with GERD, hiatal hernia is a significant pathophysiologic factor. The esophagogastric junction (EGJ) is anatomically and physiologically complex, making it vulnerable to dysfunction by several mechanisms, including transient relaxations of the lower esophageal sphincter (LES), hypotensive LES, and anatomic disruption. The importance of hiatal hernia is obscured by imprecise use of the term and by the misconception that it is an all-or-none, one-dimensional phenomenon. Rather, hiatal hernia can be viewed as a continuum of progressive disruption of the EGJ, with larger hernias being of greater significance and invoking several pathogenetic mechanisms. The dynamic anatomy of the EGJ highlights the difficulty of defining hiatal hernia and of elucidating the relation between hiatal hernia, the diaphragmatic hiatus, the LES, and GERD, including supraesophageal reflux.

Diaphragm↗
PubMed2001

Manometric heterogeneity in patients with idiopathic achalasia.

BACKGROUND & AIMS: In certain cases of achalasia, particularly those in early stages with minimal endoscopic or radiographic abnormalities, the diagnosis may rely on manometry, which is the most sensitive test for the disease. The aim of this study was to critically evaluate the manometric criteria in a population of patients with idiopathic achalasia. METHODS: Clinical histories and manometric recordings of 58 patients with idiopathic achalasia and 43 control subjects were analyzed with regard to esophageal body contraction amplitude, peristaltic effectiveness in terms of both completeness and propagation velocity, lower esophageal sphincter (LES) resting pressure, LES relaxation pressure, and intraesophageal-intragastric pressure gradient. Variants of achalasia were defined by finding manometric features that significantly differed from the remainder of achalasia patients, such that the diagnosis might be questioned. RESULTS: Four manometrically distinct variants were identified. These variants were characterized by (1) the presence of high amplitude esophageal body contractions, (2) a short segment of esophageal body aperistalsis, (3) retained complete deglutitive LES relaxation, and (4) intact transient LES relaxation. In each instance, the most extreme variant is discussed and compared with the remainder of the achalasia population and with controls. CONCLUSIONS: The significance in defining these variants of achalasia lies in the recognition that these sometimes confusing manometric findings are consistent with achalasia when combined with additional clinical data supportive of the diagnosis. Furthermore, such variants provide important clues into the pathophysiology of this rare disorder.

Adult↗