PRIMARY PERISTALSIS IS THE MAJOR ACID CLEARANCE MECHANISM IN REFLUX PATIENTS

This study examined the clearance of gastric acid from the oesophagus in ambulant patients with gastrooesophageal reflux. Eighteen patients with proved reflux disease were studied, nine with (group 1) and nine without (group 2) endoscopic oesophagitis. Oesophageal pressure and pH were recorded over 24 hours. Pressures were measured by a probe with five sensors: a 5 cm long sensor in the lower oesophageal sphincter, t hree sensors in the body of the oesophagus, and one at the pharynx to detect swallowing. Oesophageal pH was monitored 5 cm above the lower o esophageal sphincter. Manometric activities were classified as either peristaltic or ineffective. The latter included simultaneous, non-tran smitted, and amplitude peristaltic contractions. reflux episode was de fined as starting when pH fell to less than 4 and ending when the pH r ose to 5. When the rise to pH 5 took place in three or more discrete s teps after motor responses to gastrooesophageal reflux, the pH steps w ere labelled as initial change (I), middle changes (M), and last chang e (L). A total of 595 episodes of gastro-oesophageal reflux and 1626 a ssociated motor events were analysed. Of these, 1331 (81.9%) were clas sed as primary peristaltic activity, 174 (10.7%) as primary ineffectiv e activity, 46 (2.8%) as secondary peristaltic activity, and 75 (4.6%) as secondary ineffective activity. There were no significant differen ces in initial change (p>0.05), middle changes (p>0.05), and last chan ge (p>0.05) between group 1 and group 2. In all patients, the successi ve changes of pH in response to motor activity were significantly diff erent (p=0.0001) between initial, middle, and last changes. Last chang e was significantly higher when compared with initial (p=0.001) and mi ddle changes (p<0.001). Primary oesophageal peristalsis was the most f requent motor response to gastrooesophageal reflux. The last motor act ivity during reflux showed the greatest change in pH.