Does Age Delay Gastric Emptying? Ultrasound Reveals Altered Dynamics in the Aged Population

Kai Yang¹Tao Huang²Lina Yu³Yiyang Tang³Bijing Li³Gaofeng Zhao^3,4Wenfei Long^5*

• ¹The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, Guangdong Province, China
• ²Fengshun County Traditional Chinese Medicine Hospital of Guangdong Province, Meizhou, Guangdong Province, China
• ³The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
• ⁴State Key Laboratory of Traditional Chinese Medicine Syndrome, Guangzhou, Guangdong Province, China
• ⁵Second Clinical Medical College, Guangzhou University of Traditional Chinese Medicine, Guangzhou, China

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/m². Participants underwent gastric ultrasound measurements every 15 minutes during a 120-minute period after drinking 300 mL of water and at seven time points during a 240-minute 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 minutes; 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.