Study Debates Effectiveness of Sellick's Maneuver to Prevent Aspiration
Sellick's maneuver is a simple technique that is widely used to prevent aspiration (inhaling) of the stomach contents in anesthetized patients. But does it work as advertised? That's the question asked by a study in the November issue of Anesthesia & Analgesia, official journal of the International Anesthesia Research Society (IARS).
The study provides new information about exactly how the Sellick's maneuver works to narrow the passage between the esophagus and throat. However, leading experts still disagree about whether this widely used technique is necessary or effective in preventing aspiration during anesthesia.
Dr. Mark J. Rice and colleagues of University of Florida, Gainesville, evaluated the effects of the Sellick's maneuver in 24 healthy adults. Sellick's maneuver is performed by pressing down on the anesthetized patient's neck, right below the thyroid cartilage ("Adam's apple"). This is thought to compress the esophagus--closing the upper end and keeping the stomach contents where they belong. The pressure is released once a tube is placed to protect the patient's airway during surgery.
However, using MRI scans, the researchers found that that's not exactly how it works. "It turns out that the esophagus starts lower than the location in the neck where the Sellick's maneuver is applied," explained Dr. Steven L. Shafer of Columbia University, Editor-in-Chief of Anesthesia & Analgesia. "When the neck is compressed, it is the lower throat, and not the esophagus, that is compressed." The MRI scans showed about a one-third reduction in the diameter of the lower throat during the Sellick's maneuver.
When patients are anesthetized, the contents of the stomach can easily rise up through the esophagus and into the mouth. If even a small amount of acid, bile, or stomach contents enters the lungs, it can cause serious problems like pneumonia and respiratory distress syndrome. "This is the reason anesthesiologists always instruct patients to refrain from eating anything for many hours before surgery," Shafer said.
The new research suggests that compression of the lower throat by the Sellick's maneuver is probably enough to block food from welling up from the stomach. But is it effective or necessary to prevent aspiration? In dueling editorials, two noted experts--Dr. Andranik Ovassapian from The University of Chicago and Dr. Jerrold Lerman from Strong Memorial Hospital, Rochester, N.Y.--reach opposing conclusions. Ovassapian believes that the new study provides "strong support to the efficacy of Sellick's maneuver in occluding the alimentary tract posterior to the cricoid cartilage." However, Lerman writes, "Currently, there is insufficient evidence to advocate or abandon the use of cricoid pressure to prevent passive regurgitation in at-risk anesthetized patients."
Thus even expert anesthesiologists aren't in agreement as to whether the Sellick's maneuver is effective in preventing the stomach contents from reaching the lungs. The message for patients, according to Shafer, is to follow the anesthesiologist's instructions about not eating before surgery: "The safest way to keep food, acid, and bile out of the lungs during general anesthesia is to start with an empty stomach."
Read the full study, click here.