The role of perioperative chewing gum on gastric fluid volume and gastric pH: a meta-analysis

A review of pediatric fasting guidelines and strategies to help children manage preoperative fasting

Fasting for surgery is a routine step in the preoperative preparation for surgery. There have however been increasing concerns with regard to the high incidence of prolonged fasting in children, and the subsequent psycho-social distress and physiological consequences that this poses. Additionally, the past few years have yielded new research that has shown significant inter-individual variation in gastric emptying regardless of the length of the fast, with some patients still having residual gastric contents even after prolonged fasts. Additionally, multiple large-scale studies have shown no long-term sequalae from clear fluid aspiration, although two deaths from aspiration have been reported within the large Wake Up Safe cohort. This has led to a change in the recommended clear fluid fasting times in multiple international pediatric societies; similarly, many societies continue to recommend traditional fasting times. Multiple fasting strategies exist in the literature, though these have mostly been studied and implemented in the adult population. This review hopes to summarize the recent updates in fasting guidelines, discuss the issues surrounding prolonged fasting, and explore potential tolerance strategies for children.

Efficacy and safety of preoperative chewing gum for undergoing elective surgery: A meta-analysis of randomised controlled trials

AIMS AND OBJECTIVES

This meta-analysis aimed to investigate the safety and feasibility of preoperative chewing gum in adult patients undergoing elective surgery.

BACKGROUND

Postoperative chewing gum has been shown to be safe and effective for most surgeries, while the safety and efficacy of preoperative chewing gum are still controversial.

DESIGN

A meta-analysis of randomised controlled trials was performed.

NO PATIENT OR PUBLIC CONTRIBUTION

This was a meta-analysis involving no people or animals.

METHODS

The literature search was performed in 9 databases from inception to July 2022. Randomised controlled trials that compared the safety and efficacy of preoperative chewing gum and preoperative chewing no gum in adult patients undergoing elective surgery were included. The study was reported in compliance with PRISMA statement.

TRIAL REGISTRATION

PROSPERO CRD42022330223.

RESULTS

Fourteen trials involving 1433 adult patients who undergo elective surgery were pooled in this meta-analysis. The results showed that preoperative chewing gum group resulted in no significant difference in gastric pH (p = .13) and gastric fluid volume (p = .25) compared with non-gum-chewing group. In comparison with the non-gum-chewing group, the gum-chewing group was associated with shorter preoperative thirst score (p = .02), lower incidence of postoperative nausea (p = .0004), lower incidence of postoperative sore throat, lower incidence of postoperative hoarseness, lower postoperative pain score, shorter first postoperative anal exhaust time (p < .00001), shorter first postoperative defecation time (p < .00001) and shorter hospital days (p = .02).

CONCLUSIONS

Preoperative chewing gum was associated with lower discomforts and complication rates, without increasing gastric pH and gastric fluid volume. This strategy may be an innovative, feasible and safe choice for elective surgery in adults.

RELEVANCE TO CLINICAL PRACTICE

This study's results could be used as an evidence for the implementation of preoperative chewing gum in perioperative care for adult patients undergoing elective surgery.

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.

Effect of a carbohydrṇate lollipop on the gastric volume of fasted pediatric patients

BACKGROUND

Preoperative fasting is part of routine practice. Children subjected to prolonged preoperative fasting often suffer adverse effects. Consuming a preoperative lollipop may lessen their anxiety and have clinical benefits.

AIMS

To assess the effect of consuming a lollipop on gastric volume and the feasibility of administering a lollipop to a child preoperatively.

METHODS

In this prospective, repeated measures interventional study, we measured gastric antrum volume using ultrasound in children aged 2-18 years. We measured antrum volumes after participants had fasted for a minimum of 6 h for solids and 2 h for clear fluids. They then consumed a standard carbohydrate lollipop, and we repeated the antrum volume measurements after 1 h.

RESULTS

Of the 38 patients enrolled, 32 completed the study; four had ingested additional food or liquid, and two were diagnosed with systemic disease the day after data collection. The gastric volume data were normally distributed. The mean volume change was 0.01 ml kg^-1 (95% CI -0.02 to 0.05; p = .460). The mean postlollipop volume was 0.51 ml kg^-1 (95% CI 0.43 to 0.58).

CONCLUSIONS

Consuming a standard lollipop did not affect the gastric volume of fasted pediatric patients.

Anxiolytic effects of chewing gum during preoperative fasting and patient-centered outcome in female patients undergoing elective gynecologic surgery: randomized controlled study

Although previous studies reported that chewing gum during the preoperative fasting has the benefits of alleviating anxiety and dry mouth, preoperative chewing gum has yet to be accepted as a standard practice due to conventional anesthetic custom. Our study aimed to prospectively evaluate the effects of gum chewing on preoperative anxiety and patient's discomfort in female patients undergoing gynecologic surgery. Ninety-four patients were enrolled and randomized either into conventional fasting group (control group) or chewing gum with fasting group (gum group). The control group was instructed to fast from 3 p.m. on the day before surgery. The gum group performed preoperative fasting in the same manner, but was encouraged to chew gum freely during the fasting period. The primary endpoint was the degree of preoperative anxiety. For the evaluation of preoperative anxiety, Amsterdam preoperative anxiety and information scale (APAIS) was used. Preoperative gastric fluid volume and acidity were also measured as the secondary outcomes. Preoperative anxiety using APAIS was significantly lower in the gum group compared to the control group (control group vs. gum group: 20.9 vs. 17.8, p = 0.009). However, there was no significant difference in the gastric fluid analysis between the groups. In the female patients for elective gynecologic surgery, chewing gum during the preoperative fasting period helped to alleviate preoperative anxiety without additional increase of pulmonary aspiration risks.Trial registration: KCT0004422 (05/11/2019, https://cris.nih.go.kr ; registration number).

Multicenter Survey on Staff Understanding of Preoperative Fasting Guidelines

PURPOSE

To assess the knowledge of nursing staff regarding pediatric preoperative fasting in a tertiary pediatric center and a general hospital.

DESIGN

Anonymous electronic survey with nine questions modified to each institution.

METHODS

This was a prospective quantitative study. Nursing staff at a tertiary pediatric center and pediatric nursing staff at a general hospital with pediatric services were eligible for participation. An anonymous electronic survey with nine questions via Survey Monkey was used over a 2-month period.

FINDINGS

There were 295 participants from the tertiary pediatric center and 24 from the general hospital which represented 10% of overall nursing staff at the tertiary pediatric center and approximately 50% of pediatric nursing staff at the general hospital. At both the tertiary pediatric center and the general hospital, 50 to 80% of participants correctly answered most questions. More participants were correct for the fasting times for infants less than 6 month of age than for those over 6 months old. For clear fluids, 61 (20.7%) and 13 (4.4%) considered jelly and breast milk as clear fluids respectively at the tertiary pediatric center.

CONCLUSIONS

Preoperative fasting continues to be a core area of pediatric care that is not completely understood. Our survey showed that although the majority of staff claim to be able to access the hospital guidelines, knowledge of these guidelines can be improved. In light of ongoing changing evidence, it is clear that education is a key factor in reducing morbidity and improving patient experience related to preoperative fasting.

Pre-operative fasting in children: A guideline from the European Society of Anaesthesiology and Intensive Care

Current paediatric anaesthetic fasting guidelines have recommended conservative fasting regimes for many years and have not altered much in the last decades. Recent publications have employed more liberal fasting regimes with no evidence of increased aspiration or regurgitation rates. In this first solely paediatric European Society of Anaesthesiology and Intensive Care (ESAIC) pre-operative fasting guideline, we aim to present aggregated and evidence-based summary recommendations to assist clinicians, healthcare providers, patients and parents. We identified six main topics for the literature search: studies comparing liberal with conservative regimens; impact of food composition; impact of comorbidity; the use of gastric ultrasound as a clinical tool; validation of gastric ultrasound for gastric content and gastric emptying studies; and early postoperative feeding. The literature search was performed by a professional librarian in collaboration with the ESAIC task force. Recommendations for reducing clear fluid fasting to 1 h, reducing breast milk fasting to 3 h, and allowing early postoperative feeding were the main results, with GRADE 1C or 1B evidence. The available evidence suggests that gastric ultrasound may be useful for clinical decision-making, and that allowing a 'light breakfast' may be well tolerated if the intake is well controlled. More research is needed in these areas as well as evaluation of how specific patient or treatment-related factors influence gastric emptying.

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.

Menthol chewing gum on preoperative thirst management: randomized clinical trial

Objective

to evaluate the effectiveness of menthol chewing gum, in the relief of the intensity and discomfort of the surgical patient’s thirst in the preoperative period.

Method

a randomized controlled trial, with 102 patients in the preoperative period, randomized in a control group, with usual care, and an experimental group, which received menthol gum, which was the study treatment variable. The primary clinical outcome was the variation in thirst intensity, evaluated by the Numeral Verbal Scale, and the secondary, the variation of the discomfort of thirst, evaluated by the Perioperative Thirst Discomfort Scale. Mann-Whitney test was used to compare measures between groups. The significance level adopted was of 0.05.

Results

menthol chewing gum significantly reduced the intensity (p <0.001), with Cohen’s medium-effect d, and thirst discomfort (p <0.001), with a large-effect Cohen’s d.

Conclusion

menthol chewing gum was effective in reducing the intensity and discomfort of preoperative thirst. The strategy proved to be an innovative, feasible and safe option in the use for the surgical patient, in the management of the preoperative thirst, in elective surgeries. NCT: 03200197.

Effect of chewing gum on thirst: an integrative review

OBJECTIVE

To identify and analyze the evidence on the effect of chewing gum on thirst in adults.

METHOD

Integrative review, guided by the question: "What is the scientific evidence about the effects of chewing gum on adult's thirst?" LILACS, PubMed, Scopus and Web of Science were the databases consulted.

RESULTS

Of a total of 2,414 articles found, 12 papers were selected whose publications varied between 1991 and 2016. The use of chewing gum resulted in increased salivary volume (five studies), xerostomia relief (seven studies), and thirst reduction (four studies). It was not possible to establish the number of chewing gums per day, being frequent the recommendation to use as desired. There was a predominance of studies with patients under dialysis and with cancer.

CONCLUSION

Chewing gum is an effective strategy to reduce thirst discomfort in adults.

Chewing gum for 1 h does not change gastric volume in healthy fasting subjects. A prospective observational study

STUDY OBJECTIVE

Perioperative fasting guidelines differ in their approaches to chewing gum in the preoperative period. Current recommendations range from canceling the surgery to proceeding with it. Given this lack of consensus, we performed gastric ultrasound assessments in healthy volunteers before and after a standardized period of chewing gum. The objective of our study was to determine if chewing gum for 1 h change the gastric volume.

DESIGN

Observational prospective analytical study.

SETTING

Bedside gastric ultrasound.

PATIENTS

Following institutional Review Board approval, 55 healthy (American Society of Anesthesiologists class I to II) fasted (non-surgical research) volunteers provided written informed consent to participate in the study. Morbid obesity, renal failure, diabetes mellitus, pregnancy and previous upper abdominal surgery were exclusion criteria.

INTERVENTIONS

Volunteers chewed gum for 1 h between the first and second assessment.

MEASUREMENTS

Four gastric ultrasound assessments were performed, the first one at baseline and then hourly thereafter.

MAIN RESULTS

Fifty-five healthy volunteers were studied. The proportion of subjects who presented a completely empty stomach (Grade 0 antrum) was similar at baseline and after 1 h of gum-chewing [81% vs. 84%, p = 0.19, CI 95% (-12%, 16%)]. Among those subjects who had visible fluid at baseline, the volume remained unchanged throughout the study period.

CONCLUSIONS

One hour of gum-chewing had no significant effect on the gastric fluid volume of healthy volunteers, suggesting that it may be safe for healthy subjects to chew gum prior to elective surgery.

Operative fasting guidelines and postoperative feeding in paediatric anaesthesia-current concepts

Preoperative fasting period is the prescribed time prior to any procedure done either under general anaesthesia, regional anaesthesia or sedation, when oral intake of liquids or solids are not allowed. This mandatory fasting is a safety precaution that helps to protect from pulmonary aspiration of gastric contents which may occur any time during anaesthesia. We searched PUBMED for English language articles using keywords including child, paediatric, anaesthesia, fasting, preoperative, gastric emptying. We also hand searched references from relevant review articles and major society guidelines. Association of Paediatric Anaesthesiologists of Great Britain and Ireland (APAGBI), the French Language Society of Paediatric Anaesthesiologists and the European Society of Paediatric Anesthetists recommends clear fluid intake upto one hour prior to elective surgery unless specific contraindications exists. Current guidelines recommend fasting duration of 4 hours for breastmilk, 6 hours for milk and light meals and 8 hours for fatty meals. The European Society for Clinical Nutrition and Metabolism (ESPEN) guidelines recommend that oral intake can be initiated within hours of surgery in most patients. While fluids can be started almost immediately, the introduction of solids should be done more cautiously.

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.