Development of a computer-controlled tensiometer for real-time measurements of tension in tubular organs

A computer-controlled tensiometer for studying wall tension in tubular orga ns has been developed. The system consisted of a probe with an inflatable b alloon, an impedance planimeter, pressure transducer and amplifier, a pump with RS232 interface and a PC with dedicated software. Circumferential wall tension was computed in real time from pressure and cross-sectional area m easurements (tension measurement mode). Wall tension can be maintained on a preset level or be changed as a step or ramp function by a feedback contro l of the infusion/withdrawal pump (tension control mode). A software regula tor adjusted the volume rate (low volume rate when the computed tension was close to the preset value) to minimize overshoot and oscillation. Validati on tests were performed and the technique was applied in the human oesophag us. Volume- and tension-controlled balloon distensions elicited secondary p eristalsis of increasing intensity that was decreased significantly by the antimuscarinic agent Hyoscine butyl bromide. In tension control mode Hyosci ne butyl bromide caused oesophageal relaxation, i.e. CSA to increase and pr essure to decay. Furthermore, pronounced pressure relaxation and tension re laxation were observed during volume-controlled distension after administra tion of Hyoscine butyl bromide.