Assessment of microtransducers in anorectal manometry

Abstract

It has been reported that microtransducer‐tipped catheters (transducer) produce reliable reproducible measurements which correlate well with water‐filled balloon systems. Maximum resting pressure (MRP) and maximum voluntary contraction pressures(MVC) were compared using a standard station pull‐through technique in 12 patients. There was a poor correlation for both MRP: microballoon, 115 cmH₂O (60–160 cm H₂O); transducer 60 (20–110), r = 0.62, P < 0.05, and MVC: microballoon, 202 (60–375); transducer, 175 (60–210), r = 0.42, n.s. To determine whether this was due to radial variation in pressures measured by the transducer, we studied a further 39 patients with both systems. At each station, transducer measurements were made at each of four quadrants. We found better correlation for MRP: microballoon, 100 (40–175); transducer, 66 (34–120), r = 0.72, P < 0.001, and MVC: microballoon, 225 (55–650); transducer, 180 (50–470), r = 0.87, P < 0.001, but a significant radial variation for the transducer where rotation reduced MRP pressure measurements by 21 per cent (0–600 per cent), and MVC 17 per cent (0–76 per cent). Moreover there was a significant difference between anterior and posterior MRP in the upper anal canal, anterior 35 (5–80) versus posterior 25 (10–60), P < 0.05. These results account for the poor correlation between random positioning of the microtransducer‐tipped catheter and indicate that radial orientation must be taken into account.