An Analysis of Objective pH Testing in Post-POEM Achalasia Patients
Bibliographic record
Abstract
Introduction: Achalasia is a primary esophageal motor disorder characterized by incomplete lower esophageal sphincter relaxation and loss of esophageal peristalsis. Peroral endoscopic myotomy (POEM) is a recently developed method of treating achalasia less invasively than conventional laparoscopic Heller myotomy (LHM). The reported incidence of abnormal acid exposure on ambulatory pH monitoring after POEM has been reported in literature to be 30 - 58%. However, previous studies in achalasia patients have documented the presence of pseudo-GER (gastroesophageal reflux) thought to be driven by esophageal fermentation, as opposed to true GER, but there are no studies specifically looking at this phenomenon in post-POEM patients. The aim of this study is to assess the characteristics of abnormal pH studies in post-POEM patients. Methods: This study is a retrospective review of patients with achalasia at a single tertiary center in Kingston, Ontario who underwent 24-hour ambulatory pH monitoring (Sandhill, Milwaukee, WI) after their POEM procedure. These patients also underwent EGD as part of routine clinical follow-up. Results: 19 patients underwent 24-hour ambulatory pH monitoring on PPI a median 3 (range 1 - 11) months after their POEM procedure. 7 (36%) had evidence of abnormal acid exposure (defined by pH < 4 for > 4.2% total time). 3 of these patients had endoscopic evidence of esophagitis (LA grade A - B). When the Lyon consensus criteria were applied (pH < 4 for > 6% total time for definite GERD), all 7 of these patients continued to be classified as abnormal acid exposure (reflux percent 9.5% - 59.5% total time). Visual inspection of the waveform demonstrated that all patients had evidence of true GER (rapid decrease in pH below 3.0) (figure 1), but 3 (42%) of these patients also had a fermentation pattern (slow decrease in pH not dropping below 3.7) (figure 2). Conclusion: This present study suggests that patients with achalasia are at risk for GER post-POEM. However, computerised pH analysis may be overestimating the prevalence of abnormal acid exposure, as a number of these patients demonstrated a fermentation pattern that may be mistaken by computerised analysis for true GER. Currently, our automated software and pH probe are unable to account for esophageal fermentation. Therefore, patients with achalasia post-POEM may benefit from manual analysis of pH waveform to determine a true incidence of abnormal acid exposure and GER.411_A Figure 1. 24-h pH waveform suggestive of true GER411_B Figure 2. 24-h pH waveform suggestive of esophageal fermentation
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".