CRITERIA FOR OBJECTIVE DEFINITION OF TRANSIENT LOWER ESOPHAGEAL SPHINCTER RELAXATION

We developed and evaluated objective manometric criteria that define transient lower esophageal sphincter (LES) relaxation. In 23 normal subjects and 9 patients with gastroesophageal reflux disease, systematic analysis of swallow-induced LES relaxation showed that dry swallows preceded LES relaxation by a median of 1.4 s. The relaxation rate was always >1 mmHg/s, the relaxation nadir always occurred within 7 s, and the duration of relaxation was <9 s. During concurrent esophageal manometry and pH monitoring, 104 reflux episodes associated with a LES pressure fall that was not related to swallowing were identified and the pressure falls classified as transient LES relaxations or not by visual recognition. LES pressure was always less than or equal to 2 mmHg at time of reflux, and relaxation was significantly longer than for swallow-induced LES relaxation. Of 88 pressure falls classified visually as transient LES relaxations, 90% reached nadir pressure within 7 s at a rate of > 1 mmHg/s. Sixteen pressure falls were classified as a gradual downward drift in LES pressure, which in 15 cases was <1 mmHg/s. Based on the analysis, transient LES relaxation can be defined by 1) absence of swallowing for 4 s before to 2 s after the onset of LES relaxation, 2) relaxation rate of less than or equal to 1 mmHg/s, 3) time from onset to complete relaxation of less than or equal to(1)0 s, and 4) nadir pressure of less than or equal to 2 mmHg. Excluding multiple swallows, LES pressure falls that fulfill the last three criteria but have a duration of > 10 s can also be classified as transient LES relaxations irrespective of the timing of LES relaxation to swallowing.