Ultrasound assessment of gastric volume in older adults after drinking carbohydrate-containing fluids: a prospective, nonrandomized, and noninferiority comparative study.

Purpose: The aim of this study was to evaluate the safety of drinking carbohydrate-containing fluids two hours prior to surgery in older adults using ultrasonography.

Methods: We conducted a nonrandomized and noninferiority comparative study in 60 patients aged over 65 yr who were scheduled for total knee arthroplasty. Patients who were fasted from midnight (fasting group) or who drank 400 mL of a carbohydrate-containing fluid (carbohydrate ingestion group) two hours prior to surgery were matched for age, sex, and body mass index. We measured the cross-sectional area (CSA) of gastric antrum using ultrasound and estimated the gastric fluid volume as the study's primary outcome measure. The noninferiority margin (δ) for the mean difference was predefined as 50 mL. The secondary outcome measures included CSA of the antrum and qualitative gastric volume.

Results: The mean (standard deviation) gastric volume was not significantly different between the fasting group and the carbohydrate ingestion group (30.2 [25.4] mL vs 28.4 [35.8] mL; each group, n = 30; P = 0.81). The mean difference in gastric volume was -1.9 mL (95% confidence interval [CI], -17.9 to 14.2), and the upper limit of the 95% CI was lower than the prespecified noninferiority limit (δ = 50 mL). Secondary outcomes were not significantly different between the two groups.

Conclusion: Drinking of carbohydrate-containing fluid two hours prior to surgery was noninferior to overnight fasting with respect to residual gastric volume at induction of anesthesia in healthy older adults who undergoing total knee arthroplasty.

Study registration: ClinicalTrials.gov (NCT04514380); registered 14 August 2020.