EFFECT OF CIGARETTE-SMOKING ON GASTROESOPHAGEAL REFLUX MEASURED BY 24-H AMBULATORY ESOPHAGEAL PH MONITORING

Objective: We reassessed the effect of cigarette smoking on gastroesop hageal reflux because two previous ambulatory 24-h pH monitoring studi es showed equivocal results and did not relate heartburn to changes in pH reflux events, Methods: Our protocol design considered nicotine's pharmacokinetic half-life; 14 smokers with heartburn and esophagitis a bstained from smoking for 48 h before and during an ambulatory 24-h es ophageal pH monitoring study (24-h pH), After resuming their smoking h abits for 48 h or more, they underwent a second 24-h pH study and smok ed 20 regular, filtered Marlboro cigarettes, Acid reflux was defined a s a drop in intraesophageal pH to a value < 4 at 5 cm above the lower esophageal sphincter and was measured as percent exposure and reflux e vents (total N, those greater than or equal to 5 min, and longest even t), Heartburn episodes were noted by the patients and were correlated later to acid reflux events, Results: Cigarette smoking significantly increased the percentage time that the pH was < 4 during a 24-h period from 7.35 to 11.1% (medians; p < 0.007), This increased exposure occu rred predominantly during the day while in the upright posture and res ulted from significant increases in both reflux events and those param eters that measure acid clearance (T events greater than or equal to 5 min and longest event), While smoking, the patients noted a 114% incr ease in daytime heartburn episodes that immediately followed a pH refl ux event (3.5 to 7.5 episodes, medians; p < 0.009). Conclusions: Smoki ng 20 cigarettes has a greater effect on acid reflux and heartburn tha n purported.