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.