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Three Part Question

Can[patients considered for procedural sedation in the emergency department]who have [chewed chewing gum in the preceding six hours] be [deemed fasted]?

Clinical Scenario

A 37 year old male presents with an anterior shoulder dislocation following a rugby match. He states he has not ingested solids for 6 hours or fluids for 2 hours. As you are consenting him for procedural sedation you notice he is chewing gum. Should this patient be regarded as fasted or should an alternate method of facilitating reduction be used due to an increased risk of aspiration?

Search Strategy

Using Medline database 1966 to week 3 May 2013 via OVID.
[chewing gum] AND [anaesthesia] LIMIT to human, English, abstracts

Search Outcome

29 papers of which 8 included data on patients relevant to the clinical question, 2 were unobtainable.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Poulton TJ 2012 USA	Not applicable	Literature review	Does chewing gum increase the volume or acidity of gastric juice?	No risk theoretically	Not a patient study
Schoenfelder RC et al 2006 USA	Children (5-17 yr old)	Clinical trial	Does chewing gum increase gastric fluid volume and changes gastric	Chewing gum in children have significantly larger gastric fluid volumeand higher pH.	Limited to children
Smith I et al 2011 Europe	Not stated	Meta-analyses, systematic reviews, or RCTs with a high risk of bias	Should an operation be delayed?	No risk theoretically	Not a patient study
Søreide E et al 1995 Norway	Adult females	Clinical trial	Effect on gastric fluid volume	Increased gastric fluid volume	No men in study
Dubin SA et al 1994 Augusta	Adults undergoing surgery	Clinical trial	Volume and pH of gastric content	There was no difference between groups in terms of gastric volume or pH	Non detected
Kradel et al 1992 USA	Based on one patient	Observational/Letter	Not applicable	Patient underwent anaesthesia while chewing gum, later found attached to nasogastric tube, highlights patient education issues	Only based on one patient

Comment(s)

The evidence about the risks of patients who have used chewing gum varies. Some studies conclude that chewing gum increases the volume of gastric contents while others do not. Whether this increases the risk of aspiration is unclear. All studies include patients who are undergoing anaesthesia and not sedation. Studies do not include injured patients who are the cohort of patients who are likely to present to the emergency department needing sedation.

Clinical Bottom Line

Patients who have chewed gum in the past 6 h may theoretically be at increased risk of aspiration. This should be considered when making a balanced decision about the use of procedural sedation.

References

1. Poulton TJ. Gum chewing during pre-anesthetic fasting. Paediatr Anaesth. 2012;22:288–96.
2. Schoenfelder RC, Ponnamma CM, Freyle D et al. Residual gastric fluid volume and chewing gum before surgery. Anesth Analg. 2006;102:415–17.
3. Smith I, Kranke P, Murat I et al. Perioperative fasting in adults and children: guidelines from the European Society of Anaesthesiology. Eur J Anaesthesiol 2011;28:556–569.
4. Søreide E, Holst-Larsen H, Veel T et al The effects of chewing gum on gastric content prior to induction of general anesthesia. Anesth Analg. 1995;80:985–9.
5. Dubin SA, Jense HG, McCranie JM et al. Sugarless gum chewing before surgery does not increase gastric fluid volume or acidity. Can J Anaesth 1994; 41;pp 603-6 .
6. Kradel B, Hackett A, Johnstone R. NPO includes chewing gum Anesth Analg. 1992;74:621.