Effect of Gum Chewing on the Volume and pH of Gastric Contents: A Prospective Randomized Study

2023 American Society of Anesthesiologists Practice Guidelines for Preoperative Fasting: Carbohydrate-containing Clear Liquids with or without Protein, Chewing Gum, and Pediatric Fasting Duration-A Modular Update of the 2017 American Society of Anesthesiologists Practice Guidelines for Preoperative Fasting

These practice guidelines are a modular update of the "Practice guidelines for preoperative fasting and the use of pharmacologic agents to reduce the risk of pulmonary aspiration: Application to healthy patients undergoing elective procedures." The guidance focuses on topics not addressed in the previous guideline: ingestion of carbohydrate-containing clear liquids with or without protein, chewing gum, and pediatric fasting duration.

Hard-Candy Consumption Does Not Have an Effect on Volume and pH of Gastric Content in Patients Undergoing Elective Gastrointestinal Endoscopic Procedures: A Randomized Controlled Trial

Purpose

This study aimed to determine the effect of hard candies on gastric content volume and pH in patients undergoing elective esophagogastroduodenoscopy and colonoscopy. Additionally, the study evaluated the difficulty of the procedure, complications, and satisfaction levels of the endoscopist and patient.

Patients and Methods

A randomized controlled study equally recruited 108 outpatients to candy and control groups. The patients in the candy group could consume sugar-free candies within 2 hours before anesthesia, while the controls remained fasted. The endoscopic procedure began under topical pharyngeal anesthesia and intravenous sedation. A blinded endoscopist suctioned the gastric volume through an endoscope. A blinded anesthesia provider tested the gastric pH with a pH meter. The primary outcome variables were gastric volume and pH. The secondary outcome variables were complications, the difficulty of the procedure, and endoscopist and patient satisfaction.

Results

The characteristics of both patient groups were comparable. The mean gastric volume of the candy group (0.43 [0.27-0.67] mL/kg) was not significantly different from that of the control group (0.32 [0.19-0.55] mL/kg). The gastric pH of both groups was similar: 1.40 (1.10-1.70) for the candy group and 1.40 (1.20-1.90) for the control group. The procedure-difficulty score of the candy group was higher than that of the control group. The satisfaction scores rated by the endoscopist and the patients in both groups were comparable. In addition, most endoscopists and patients in the candy and control groups reported being "very satisfied". No complications were observed in either group.

Conclusion

Hard candies did not affect gastric volume or pH. Elective gastrointestinal endoscopic procedures in adult patients who preoperatively consume candies could proceed to prevent delays and disruption of workflows.

Assessing the effect of sugar-free chewing gum use on the residual gastric volume of patients fasting for gastroscopy: A randomised controlled trial

There is no clear consensus in the current guidelines published by major international anaesthetic associations on what is the most appropriate time for a patient to stop chewing gum. This open-label balanced-group randomised controlled trial aimed to evaluate whether the chewing of sugar-free gum caused an increased volume or reduced pH of residual gastric fluid in fasting patients. For this study 212 patients undergoing elective gastroscopy were randomised into a control group who followed routine fasting instructions and an intervention group who were asked to chew gum while fasting. Residual gastric fluid was aspirated under direct vision via a gastroscope under anaesthesia. The primary outcome was the incidence of a gastric residual volume >50 ml in participants who chewed gum compared with a control group. Secondary outcomes were variability in the overall gastric volume distribution and gastric pH distribution between the two groups. Nine out of 110 (8.2%) in the chewing gum group and six out of 102 (5.9%) in the control group had a residual gastric fluid volume >50 ml: incidence rate ratio 1.39 (95% confidence intervals (CI) 0.51–3.77; P = 0.60). However, only one patient (in the control group) had a residual gastric volume >73 ml. There was no statistically significant difference in gastric volume distribution between groups, odds ratio 1.60 (95% CI 0.99–2.58; P = 0.054) or in the distribution of gastric pH measurement, odds ratio 0.90 (95% CI 0.57–1.44; P = 0.67). These results indicate that if there is an increase in the incidence of residual gastric volume >50 ml in patients who chew gum preoperatively, it is likely to be small. Moreover, the absence of any patients in our chewing gum group with a residual gastric volume >73 ml is reassuring.

Critical Analysis of Guidelines for Providing Sedation to Patients Undergoing Gastrointestinal Endoscopy Procedures

In spite of growing numbers of gastrointestinal endoscopic procedures performed under deep sedation, guidelines are lacking. Hypoxemia and aspiration continue to be the main source of morbidity. Anesthesia providers have tried to address these concerns by modifying their technique and employing newer or improvised devices. In addition, preprocedural evaluation poses many challenges. In many centers, workload pressures determine the time available to perform such an evaluation. A comprehensive history and examination similar to a major surgical procedure is often not possible. As a result, a focused history and examination is essential. This should be followed by an appropriate explanation of risks before obtaining consent. A plan should be in place to manage complications such as aspiration. This paper provides a succinct review of the above aspects.

Chewing Gum in the Preoperative Fasting Period: An Analysis of De-Identified Incidents Reported to Webairs

The role of preoperative fasting is well established in current anaesthetic practice with different guidelines for clear fluids and food. However, chewing gum may not be categorised as either food or drink by some patients, and may not always be specified in instructions given to patients about preoperative fasting. The aim of this paper was to review anaesthesia incidents involving gum chewing reported to webAIRS to obtain information on the risks, if any, of gum chewing during the preoperative fasting period. There were nine incidents involving chewing gum reported between late 2009 and early 2015. There were no adverse outcomes from the nine incidents other than postponement of surgery in three cases and cancellation in one. In particular, there were no reports of aspiration or airway obstruction. Nevertheless, there were five cases in which the gum was not detected preoperatively and was found in the patient's mouth either intraoperatively or postoperatively. These cases of undetected gum occurred despite patient and staff compliance with their current preoperative checklists. While the risk of increased gastric secretions related to chewing gum preoperatively are not known, the potential for airway obstruction if the gum is not detected and removed preoperatively is very real. We recommend that patients should be specifically advised to avoid gum chewing once fasting from clear fluids is commenced, and that a specific question regarding the presence of chewing gum should be added to all preoperative checklists.

EFFECT OF GUM CHEWING ON AIR SWALLOWING, SALIVA SWALLOWING AND BELCHING

BACKGROUND

Eructation is a physiologic event which allows gastric venting of swallowed air and most of the time is not perceived as a symptom. This is called gastric belching. Supragastric belching occurs when swallowed air does not reach the stomach and returns by mouth a short time after swallowing. This situation may cause discomfort, life limitations and problems in daily life.

OBJECTIVE

Our objective in this investigation was to evaluate if gum chewing increases the frequency of gastric and/or supragastric belches.

METHODS

Esophageal transit of liquid and gas was evaluated by impedance measurement in 16 patients with complaint of troublesome belching and in 15 controls. The Rome III criteria were used in the diagnosis of troublesome belching. The esophageal transit of liquid and gas was measured at 5 cm, 10 cm, 15 cm and 20 cm from the lower esophageal sphincter. The subjects were evaluated for 1 hour which was divided into three 20-minute periods: (1) while sitting for a 20-minute base period; (2) after the ingestion of yogurt (200 mL, 190 kcal), in which the subjects were evaluated while chewing or not chewing gum; (3) final 20-minute period in which the subjects then inverted the task of chewing or not chewing gum. In gastric belch, the air flowed from the stomach through the esophagus in oral direction and in supragastric belch the air entered the esophagus rapidly from proximal and was expulsed almost immediately in oral direction. Air swallows were characterized by an increase of at least 50% of basal impedance and saliva swallow by a decrease of at least 50% of basal impedance, that progress from proximal to distal esophagus.

RESULTS

In base period, air swallowing was more frequent in patients than in controls and saliva swallowing was more frequent in controls than in patients. There was no difference between the medians of controls and patients in the number of gastric belches and supragastric belches. In six patients, supragastric belches were seen at least once during the 20-minute base period. None of the controls had supragastric belches. In the control group, the ingestion of yogurt caused no significant alteration in the number of air swallows, saliva swallows, gastric belches and supragastric belches. In the patient group, there was an increase in the number of air swallows. If the subjects were chewing gum during this 20-minute period, there was an increase in the number of saliva swallows in both groups, without alterations of the number of air swallow, gastric belches and supragastric belches. There was no alteration in the number of the saliva swallows, air swallows, gastric belches and supragastric belches in both groups for subjects who did not chew gum in the 20-40 minute period after yogurt ingestion. When the subjects were chewing the gum, there was an increase in saliva swallows in the control and patients groups and in air swallows in the patients group.

CONCLUSION

Gum chewing causes an increase in saliva swallowing in both patients with excessive belching and in controls, and an increase in air swallowing in patients with excessive belching 20 minutes after yogurt ingestion. Gum chewing did not increase or decrease the frequency of gastric or supragastric belches.