Comparison of gastric emptying time between breast-fed and formula milk-fed infants less than 6 months old, using gastric ultrasound-An observational study

Fasting before elective anesthesia care is a standardized practice worldwide. The aim is to decrease the risk of aspiration leading to pulmonary complications such as aspiration pneumonitis during anesthesia care. There are different guidelines for elective preoperative fasting in children. However, there is insufficient literature measuring gastric emptying time after breast milk or formula milk feeding in infants.

This study used gastric ultrasound to determine the gastric emptying time for breast milk and formula milk in children below 6 months of age. We also compared the calculated gastric volumes among breast-fed and formula milk-fed based on Schmitz's and Spencer's formula.

This prospective observational study was conducted at a tertiary care center in India between November (2017-2019). A total of 52 infants less than 6 months of age were recruited. The study population was divided into two groups (breast-fed and formula milk-fed) of 26 patients each. Ultrasound was used to measure the antral cross-sectional area of the stomach and to calculate the gastric volume using the two classical formulas (Schmitz and Spencer's). Gastric emptying was reported when the bull's eye appearance of the gastric antrum was seen or when the antral cross-sectional area was less than 3.07 cm².

The number of breast-fed children whose antral cross-sectional was greater than 3.07 cm² (cut-off value for aspiration risk) beyond 1 h was 14/26 (53.84%) while none (0) children went beyond 3 h. The number of formula-fed children whose antral cross-sectional was greater than 3.07 cm² beyond 1 h was 17/26 (65.38%) while one child (3.84%) went beyond 3 h. Using Schmitz's formula, mean (SD) gastric emptying times were 0.35 ± 0.68 h (95% CI 0.35 ± 0.185, range 0.165-0.535) for breast-fed patients and 0.35 ± 0.69 h (95% CI 0.35 ± 0.188, range 0.162-0.538) for formula-fed patients, and were thus neither clinically nor statistically different (p = .73) Using Spencer's formula, the mean gastric emptying times were 0.12 ± 0.33 h (95% CI 0.12 ± 0.09, range 0.03-0.21) for breast-fed patients and 0.04 ± 0.20 h (95% CI 0.04 ± 0.05, range -0.01 to 0.09) for formula-fed patients, and were also neither clinically nor statistically different p = .13.

In our series, the gastric emptying times in breast-fed and formula-fed infants less than 6 months old were similar. Our results support the fasting guidelines of the European Society of Anaesthesiology and Intensive Care 2022, that is, 3 h for breastfeeding and 4 h for formula milk feeding. In addition, this shows that the Schmitz's and Spencer's formulae used to calculate the gastric volume based on ultrasound measurement of the antral cross-sectional area are not comparable in infants less than 6 months.