The findings appeared in the journal Digestive Diseases and Sciences.
Patients who are fasting before upper endoscopy can safely chew gum up until the time of the procedure, researchers have found.
Guidelines on preoperative fasting from the American Society of Anesthesiologists do not explicitly address gum chewing. However, many anesthesia departments prohibit sedation in such patients because gum chewing is considered the ingestion of a clear liquid. As a result, many patients end up having procedures delayed or cancelled when they report having chewed gum—unnecessarily, the new data suggest.
“The effect of chewing gum on fasting has been a subject of debate. We found that although chewing gum does increase the production of saliva and thus the residual gastric volume, it does not increase pH,” said Basavana Goudra, MD, assistant professor of anesthesiology and critical care medicine at the Hospital of the University of Pennsylvania, in Philadelphia, who led the study. “We think that gum chewing before a procedure may help to allay anxiety in patients and increase their comfort and satisfaction. Patients who have chewed gum inadvertently should not face delays or cancellations.”
The prospective randomized controlled study evaluated the effect of gum chewing on volume and pH of gastric contents in 67 patients scheduled to receive IV conscious sedation for upper endoscopy. The night before the procedure, patients were randomly assigned to chew gum until the start of sedation—using fentanyl, midazolam and occasionally diphenhydramine—or to not chew gum, with no limit on the number of pieces or how long they could chew.
“The aim was to reflect real-life gum-chewing habits,” Mr. Carlin said.
After insertion of the endoscope, stomach contents were suctioned completely under direct vision and the volume and pH of stomach contents were measured.
“We found a significant difference in gastric volume,” Mr. Carlin reported. “However, the increase in residual volume was smaller than what we expected and therefore it failed to achieve clinical significance that would alter practice.”
The median volume suctioned from the gum chewers was 13 mL, compared with 6 mL for non–gum chewers. Similarly, gastric fluid also was greater for gum chewers—0.35 versus 0.11 mL/kg for patients who did not chew gum. “The 0.35 mL/kg is still under 0.4 mL/kg, which is where the risk for aspiration comes into effect,” he noted.
The mean pH value was 2.84 for gum chewers and 3.79 for non–gum chewers, a difference that did not reach statistical significance (P=0.141). “There was little to no change, and therefore no increased risk [for aspiration],” Mr. Carlin said.
Anthony Absalom, MD, professor of anesthesia at University Medical Center Groningen, in the Netherlands, said concerns about gum chewing are based on fears that the regurgitation of gastric contents into an unprotected airway will damage the lungs, and the degree of potential damage is related to the volume, nature and pH of the contents. Lower pH equates to more acid and potentially more damage, he said.
“Although the study found that gum chewing causes a slight increase in gastric volume, this was clinically insignificant and insufficient for causing lung injury if aspirated into the lungs. The pH also did not change,” Dr. Absalom noted.
“All said, the study showed no evidence that gum chewing during fasting is bad; and on this basis, I personally would not delay anesthesia because a patient chewed gum while fasting.”