Background: The authors examined the influence of metoclopramide on cricoid pressure-induced relaxation of the lower esophageal sphincter (LES) in awake human volunteers.
Methods: With local institutional review board approval, measurements of LES and intragastric pressures were made in 10 consenting volunteers before cricoid pressure application, during 15 s of cricoid pressure application, and after release of cricoid pressure. The measurements were repeated after 0.15 mg/kg intravenous metoclopramide. Cricoid pressure was applied by one investigator trained to consistently apply a force of 44 N.
Results: Cricoid pressure resulted in immediate decrease in LES and barrier pressures from 14.1 +/- 2.9 mmHg to 3.2 +/- 3.7 mmHg and from 9.6 +/- 3.4 mmHg to -1.8 +/- 2.9 mmHg, respectively. These pressures promptly returned to baseline values after release of cricoid pressure. LES and barrier pressures increased after metoclopramide from 14.5 +/- 3.1 to 19.6 +/- 4.7 mmHg and from 10.2 +/- 3.6 to 14.1 +/- 5.5 mmHg, respectively. Cricoid pressure applied after metoclopramide resulted in immediate decreases in LES and barrier pressures to levels comparable to cricoid pressure before metoclopramide, but immediately returned to precricoid values after release of pressure.
Conclusions: The current investigation demonstrates that cricoid pressure reflexly decreases LES tone and barrier pressure in awake subjects. Although metoclopramide increased LES and barrier pressures, it did not attenuate cricoid pressure-induced relaxation of the LES and barrier pressures and thus seems to have no value in preventing gastroesophageal reflux during cricoid pressure. Metoclopramide may be useful in preventing reflux when there is need to release or discontinue cricoid pressure.