24 hour ambulatory oesophageal motility monitoring: how should motility data be analysed?

Ambulatory oesophageal motility/pH monitoring permits accurate detection of oesophageal events during spontaneous chest pain episodes. Opinions differ, however, about the methods to review the extensive motility data and the definition of abnormal motility changes. We studied 30 patients (18 women, age 46 years) with suspected oesophageal chest pain using a portable recording system attached to a 4.5 mm catheter with pressure transducers 3 and 8 cm and pH probe 5 cm above the lower oesophageal sphincter (LOS). An event marker was triggered by the patient for chest pain. In the patient's diary, pain was recorded on a scale of increasing severity 1-10. Two methods of analysis were used to assess 24 hour motility data. The 24 hour technique sampled five minute asymptomatic baselines throughout the study to define the patient's normal range of oesophageal motility. The second technique used only the 10 minute period immediately before each chest pain episode as the asymptomatic baseline. Chest pain episodes were defined as abnormal if associated with pH less than 4 or motility changes not present during the asymptomatic baseline analysis: 135 chest pain episodes were recorded. The method of motility analysis significantly (p less than 0.01) changed the number of chest pain episodes associated with abnormal motility: 24 hour technique - 14 episodes (10%) versus a 2.5-fold increase with the 10 minute baseline technique - 33 episodes (24%). Acid related pain episodes were similar in both groups - 13%. The majority of chest pain episodes had no association with abnormal motility or acid reflux. Increasing chest pain severity was inversely correlated with the presence of abnormal oesophageal events. We conclude that limited analysis of 24 hour motility data may over diagnose motility related chest pain events and lead to inappropriate medical or surgical therapy.