Optimal number of multiple rapid swallows needed during high-resolution esophageal manometry for accurate prediction of contraction reserve

Background Multiple rapid swallows (MRS) is a provocative test for assessment of contraction reserve, however reproducibility on repetitive MRS is incompletely understood. Our aim was to determine the optimal number of MRS sequences for consistent assessment of contraction reserve. Methods One hundred and fifty-nine consecutive patients (79 IEM and 80 normal motility) who underwent high-resolution manometers were enrolled. Ten single swallows (SS) and 10 MRS were performed. Gold standard for evaluation of the contraction reserve was the ratio between the mean DCI of 10 MRS and the mean DCI of 10 SS (MRS/SS DCI ratio). Rates of false negatives and false positives were calculated for increasing numbers of MRS sequences, using either mean DCI or the MRS with the highest DCI. Key results According to the gold standard, 50 IEM and 50 normal motility patients had contraction reserve. With progressively increasing numbers of MRS sequences, contraction reserve was detected using mean MRS DCI within three and four MRS sequences in IEM and normal motility respectively, whereas two and three MRS sequences were needed using the MRS sequence with the highest DCI. False positives were much higher with highest DCI method compared with mean DCI, (22% vs 9% respectively in IEM; 24% vs 9% in normal motility) when three MRS sequences were considered. Conclusions & inferences At least three MRS are needed to reliably assess contraction reserve. The mean DCI of the three MRS sequences is the best variable to utilize as evidence of contraction reserve.