A novel high-resolution anorectal manometry parameter based on a three-dimensional integrated pressurized volume of a spatiotemporal plot, for predicting balloon expulsion in asymptomatic normal individuals

Background Anorectal manometry with simulated evacuation (SE) has limited applicability in predicting balloon expulsion (BE) test results. The newly developed high-resolution anorectal manometry (HRAM) technique can yield spatiotemporal plots with three-dimensional pressurization. We aimed to define new parameters based on three-dimensional integrated pressurized volume (IPV) for predicting the BE test results in asymptomatic normal individuals. Methods Fifty-four asymptomatic healthy individuals were prospectively enrolled. BE tests were performed using 50mL of water, and a requirement of more than 1min was considered as delayed BE. HRAM profiles were converted into ASCII files and analyzed using a MATLAB program. A three-dimensional IPV was plotted after transforming the data to a cubic spline interpolation followed by resampling the manometry position at 0.1-cm intervals. Key Results Eight of the 54 (15%) individuals demonstrated delayed BE. Conventional manometric profiles did not differ significantly between cases of early and delayed BE. Receiver-operator characteristic curve analysis revealed that the ratio of the IPVs of the upper 1cm to the lower 4cm of the anorectal canal with balloon distension was more predictable of the BE results (area under curve, 0.73: 95% confidence interval, 0.53-0.92; p=0.04) than the other IPVs or their ratios. Conclusions & Inferences The newly developed IPV methods could predict delayed BE tests during SE better than the conventional parameters defined on the basis of linear waves. Well-designed prospective trials on a large number of subjects are warranted to validate the clinical application of this novel parameter.