Objective: We reassessed the effect of cigarette smoking on gastroesophageal reflux because two previous ambulatory 24-h pH monitoring studies 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 abstained from smoking for 48 h before and during an ambulatory 24-h esophageal pH monitoring study (24-h pH). After resuming their smoking habits for 48 h or more, they underwent a second 24-h pH study and smoked 20 regular, filtered Marlboro cigarettes. Acid reflux was defined as 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 events (total N, those > or = 5 min, and longest event). 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 occurred predominantly during the day while in the upright posture and resulted from significant increases in both reflux events and those parameters that measure acid clearance (T events > or = 5 min and longest event). While smoking, the patients noted a 114% increase in daytime heartburn episodes that immediately followed a pH reflux event (3.5 to 7.5 episodes, medians; p < 0.009).
Conclusions: Smoking 20 cigarettes has a greater effect on acid reflux and heartburn than purported.