Oesophageal manometry: how well does it predict oesophageal function

The variability in manometric measurements of oesophageal peristalsis was assessed in 10 volunteers. The amplitude, velocity and duration of the peristaltic waves resulting from 10 separate 10 ml boluses of water were measured at fixed distances above the lower oesophageal sphincter (LOS). After a 10 minute rest period with the manometry catheter still in situ peristaltic values in response to a second group of 10 10 ml boluses were measured. The measurement of peristaltic amplitude at a fixed distance above the LOS showed wide interindividual variation--for example, at 8 cm above the LOS the variation between individuals was marked (p less than 0.001). At the same site, however, there was only a small intra individual variation noted with time (p greater than 0.25). Similar differences were noted at 16 and 4 cm above the LOS. For the first group of swallows, while the interindividual variation remained high (p less than 0.025), the measurement variation from site to site was of lesser magnitude (p greater than 0.1). Similar findings were noted for interindividual variation and site to site variation at the second group of swallows. The values for velocity showed a similar pattern of variation. From this study we conclude that manometric measurements can be used as a valid method for assessing the effects of drugs on peristalsis in individuals provided all measurements are made at the exact same level in the oesophagus and 'normal' subjects with a large inherent variation are excluded. Any studies comparing peristaltic values in different population groups - for example, normal v reflux patients, may not detect any significant difference even with large sample numbers. Any differences detected may be of no clinical importance because of the large normal variation.