Reproducibility and performance characteristics of colonic compliance, tone, and sensory tests in healthy humans

Background The performance characteristics of colonic sensation and motility measurements are unclear. Aim To compare left colon compliance, tone, and sensation in males and females and to evaluate inter and intra-individual coefficients of variation (COV) in these measurements. Methods Data were acquired using standard barostat methods, by one technologist, in 72 human volunteers (38 males, 18-65 years). We measured compliance, fasting tone, and sensation during baseline and post-placebo; postprandial (PP) tone was measured only post-placebo. Compliance and thresholds for first sensation, gas, and pain were measured using ascending method of limits; sensory ratings (0-100 mm VAS) using random phasic distensions at 8-36 mmHg above baseline operating pressure. Change in PP tone was measured by barostat balloon volume for the first 30 min after a 1000-kcal meal. Inter-COV was calculated as 100 (SD/mean), and intra-COV as (100 × SD delta/overall mean). Results There were no statistically significant associations with gender for most sensory or motor data at baseline. A modest association of fasting colonic tone and gender was observed. COV are lower (20-35%) for compliance, fasting tone, pain threshold, and sensation ratings than for PP tone and threshold for first or gas sensation (>45%). COV data are similar in males and females; sensation COVs appear smaller in females than in males. Conclusions Testing of compliance, tone and pain, and gas sensation in left colon performs adequately to assess these functions in humans. Lower COV for sensation tests among females is relevant to plan studies of drugs intended for functional GI disorders.