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Opioids can affect gastric, small-bowel, and colonic motility via opioid receptors in the submucosal and myenteric plexus neurons. The distribution of these receptors and associated opioid use effect in the esophagus are unclear; the small studies conducted to date have shown conflicting results.
To investigate this issue further, researchers retrospectively evaluated esophageal high-resolution manometry (HRM) and the Chicago classification reporting system in 121 chronic opioid users, comparing results between 66 patients who were currently on opioids and 55 patients who had been off opioids for ≥24 hours. The most frequent indications for HRM were dysphagia (55%), gastroesophageal reflux (26%), and chest pain (12%). The demographics of patients were similar between those on or off opioids on the day of HRM.
Compared with patients evaluated while off opioids, patients on opioids had a higher mean integrated relaxation pressure (10.7 vs. 6.6 mm Hg; P=0.025) and a higher frequency of rapid contractions with reduced distal latency (6.2 vs. 6.7 s; P=0.044), consistent with achalasia type III and/or esophagogastric junction (EGJ) outflow obstruction.
Ratuapli SK et al. Opioid-induced esophageal dysfunction (OIED) in patients on chronic opioids. Am J Gastroenterol 2015 Jul; 110:979. (http://dx.doi.org/10.1038/ajg.2015.154)
Comment
The precise mechanism of opioid-related esophageal spastic dysmotility is unclear, but it is likely a tonic spasm effect on smooth muscle through inhibiting release of nitric oxide; this leads to unopposed excitatory input, which can induce spastic esophageal dysmotility. Although the clinical relevance of the manometric patterns suggestive of EGJ outflow obstruction or type III achalasia observed in patients on opioids at the time of HRM were not reported, such findings should be interpreted with caution and HRM repeated after the patient is off opioids for ≥24 hrs.