CRICOID CARTILAGE PRESSURE DECREASES LOWER ESOPHAGEAL SPHINCTER TONE

Background: Cricoid cartilage pressure induced to prevent pulmonary as piration from regurgitation of gastric contents has been recommended, and its efficacy requires a force greater than 40 Newtons. For regurgi tation to occur, both an increase in gastric pressure and relaxation o f the lower esophageal sphincter (LES) are necessary. However, the eff ect of cricoid cartilage pressure on the LES is unknown, This study ev aluated the effects of cricoid cartilage pressure on LES in human volu nteers. Methods: Lower esophageal sphincter and esophageal barrier pre ssures (which equals LES pressure - gastric pressure) were measured us ing a manometric method in eight unanesthetized volunteers (4 men, 4 w omen) classified as American Society of Anesthesiologists physical sta tus 1. The force applied to the cricoid cartilage was measured continu ously, and LES pressure was recorded at a cricoid force of 20 and 40 N ewtons, Results: Cricoid pressure decreased LES pressure from 24 +/- 3 mmHg to 15 +/- 4 mmHg at a force of 20 Newtons (P < 0.05) and to 12 /- 4 mmHg with a force of 40 Newtons (P < 0.01). Conclusions: These fi ndings may explain the occurrence of pulmonary aspiration before trach eal intubation despite application of cricoid cartilage pressure.