Does age delay gastric emptying? Ultrasound reveals altered dynamics in the aged population

Background The current preoperative fasting guideline of American Society of Anesthesiologists for adults, including younger and older adults, is 8 h of fasting. However, differences in gastric emptying between younger and older adults remain unclear. To determine fluid emptying time and 4 h gastric emptying rate (4HGER) in younger and older adults by evaluating the gastric antrum using ultrasound after ingestion of a rice-based meal. Methods A total of 60 participants were enrolled, including 30 older adults (aged 65–80 years; median age 71.5 years) and 30 younger adults (aged 18–64 years; median age 41.5 years) with BMI ranging from 18 to 30 kg/m 2 . Participants underwent gastric ultrasound measurements every 15 min during a 120 min period after drinking 300 mL of water and at seven time points during a 240 min period after ingesting a 550 kcal rice-based meal. Gastric antral cross-sectional area (CSA) was measured, gastric volume (GV) was calculated, and 4HGER was determined based on CSA changes. Additional measurements included blood glucose levels and hunger scores using a numeric rating scale (NRS). Results No significant difference was observed in fluid emptying time between younger and older adults (median 45 min; P = 0.737). However, the mean 4HGER was significantly lower in older adults (35% ± 9%) compared to younger adults (51% ± 12%; P 0.05). Age and BMI were significant predictors of gastric emptying, with older age and higher BMI associated with delayed solid gastric emptying. Blood glucose levels were higher in older adults postprandially, but hunger scores did not significantly differ between groups. Conclusion Gastric emptying of solid food, as assessed by ultrasound, is significantly delayed in older adults compared to younger adults, while liquid emptying time remains unaffected. These findings highlight the need to reconsider current fasting guidelines for older adults to minimize perioperative complications such as aspiration and hypoglycemia. The results have important clinical relevance for optimizing preoperative fasting protocols in elderly patients undergoing anesthesia. Clinical Trial Registration Clinicaltrials.gov identifier ChiCTR2100045201 (date of registration: 8th April, 2021).