Rigorous, peer-reviewed guidelines exist from ASA toward the preoperative fasting period.1 While these guidelines are exhaustive, they fail to directly address chewing gum, an issue of controversy within the literature.
The effect of chewing gum toward raising intragastric volume has been proven in several small trials. A randomized trial of 21 patients found a statistically significant increase in intragastric volume, but the same trial did not find a significant difference in gastric pH.2 Similar results were found in a study looking for prevention of preoperative mouth dryness – and chewing gum failed to provide a suitable intervention.3 Nicotine chewing gum was assessed, to no avail, in a randomized clinical trial to ease the perioperative fasting period in smokers.4 The same results may be exaggerated by coexisting disease. A morbidly obese man undergoing obesity surgery admitted to chewing gum two hours prior to surgery and reported throwing out the gum. Upon direct laryngoscopy, the patient regurgitated 90 ml of saliva, complicating intubation efforts.5
Mechanical obstruction of esophageal probes and endotracheal adjuncts are also reported. Physicians were unable to pass an esophageal gastric tube in a patient who had admitted to chewing gum and “losing it in the mouth.”6 Disturbingly, there are numerous reports of chewing gum on laryngeal mask airways,7,8 obstructing the function of the cuff of an endotracheal tube,9 and causing disturbing sounds in the airway.10 Fortunately, only one case exists in the literature of a mortality, albeit a distant one.11 And even though this mortality was associated with chewing tobacco, rather than chewing gum, it remains as a cautionary tale.11
Internationally, the issue of chewing gum during the preoperative fasting period is directly addressed. The U.K. National Health Service provides guidelines that include chewing gum as part of the solid food section of the preoperative fasting guideline and states that it should be abstained from during the six hours preceding surgery.12 This is in conjunction with the guidelines set forth by the Association of Anesthetists of Great Britain and Ireland and the Royal College of Anesthetists.13 The European Society of Anaesthesiology, however, advocates not canceling cases if a patient is found to be chewing gum, although it provides no direct evidence of the safety of this position.14
In our opinion, chewing gum provides the added risk of aspiration and catastrophe during anesthesia and has no therapeutic benefit. The current NPO guidelines should be amended to include chewing gum as part of the solid foods section, and patients should be expressly consulted to avoid chewing gum during the NPO period.
For a complete list of references, please refer to the back of the online version of the ASA NEWSLETTER at asahq.org or email j.reid@asahq.org.
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