Ultrasound Evaluation of Gastric Emptying Time in Healthy Term Neonates after Formula Feeding

Abstract

Background: The current American Society of Anesthesiologists fasting guideline for formula-fed infants in the periprocedural setting is 6 h. Prolonged fasting in very young infants is associated with an increased risk for hypoglycemia and dehydration as well as patient discomfort and patient/parental dissatisfaction. This study aimed to determine the time to gastric emptying in healthy neonates after formula feeding by serially evaluating the gastric antrum with ultrasound. The authors hypothesized that gastric emptying times in formula-fed neonates are significantly shorter than the current 6 h fasting recommendation. Methods: After institutional review board approval and written informed parental consent, ultrasound examination was performed in healthy full-term neonates before and after formula feeding at 15-min intervals until return to baseline. Ultrasound images of the gastric antrum were measured to obtain cross-sectional areas, which were then used to estimate gastric antral volumes. Results: Forty-six of 48 recruited neonates were included in the final analysis. Gastric emptying times ranged from 45 to 150 min and averaged 92.9 min (95% CI, 80.2 to 105.7 min; 99% CI, 76.0 to 109.8 min) in the overall study group. No significant differences were found in times to gastric emptying between male and female neonates (male: mean, 93.3 [95% CI, 82.4 to 104.2 min]; female: mean, 92.6 [95% CI, 82.0 to 103.2 min]; P = 0.930) or those delivered by vaginal versus cesarean routes (vaginal: mean, 93.9 [95% CI, 81.7 to 106.1 min]; cesarean: mean, 92.2 [95% CI, 82.5 to 101.9 min]; P = 0.819). Conclusions: These results demonstrate that gastric emptying times are substantially less than the current fasting guideline of 6 h for formula-fed, healthy term neonates. Serial ultrasound imaging of the gastric antrum in healthy term neonates after formula feeding reveals gastric emptying times ranging from 45 to 150 min. These observations suggest that preanesthesia fasting of healthy term neonates could be substantially shorter than is currently recommended.