Shortening fasting times in young children undergoing general anesthesia aims to avoid the detrimental effects of prolonged fasting. However, the quantities of acidified milk that might be expected in the stomach following a shortened fast have not yet been fully investigated. The role of gastric ultrasound in quantifying particulate gastric content is not fully understood.

Prolonged fasting prior to general anaesthesia (GA) is common in children. It is associated with dehydration, hypoglycemia, and ketoacidosis in up to 28 % of children under 3 years, as well as distress in children and their families.

The purpose of pre-operative fasting is to reduce the volume, acidity, and particulate nature of any gastric contents; therefore, if an aspiration event occurs, lung damage will be minimal. Although pulmonary aspiration events are rare in children, data from animal models suggest that the volume, and presence of particulate matter, such as that seen in acidified breast or formula milk, can affect the patterns of lung damage. Aspiration of volumes greater than 0.8 ml.kg-1 appear to be the most harmful in animal models, regardless of pH.

In humans, gastric emptying of breast and formula milk preparations has been extensively studied in the neonatal setting in preterm and low-birth-weight infants. The majority used serial measurements of antral cross-sectional area (ACSA) with gastric ultrasound (US) and reported the return of ACSA values to baseline within 3 h for breast milk and 4 h for formula milk.

The European Society of Anesthesia and Intensive Care published guidance in 2022, advocating a 3-hour breast milk fast, and a 4-hour formula milk fast in children under 1 year undergoing elective GA. This guidance has been adopted in some tertiary centers in the UK despite the paucity of prospective studies investigating the impact of a shortened fast on gastric residual volume (GRV) measured directly (for example, by gastric aspiration).

In 2011, using data from adult elective surgical patients, Perlas et al. devised a qualitative assessment grading system to assess the gastric antrum prior to induction [15], with a view to guiding decision making regarding the induction method. various formulae that incorporate antrum grade and antrum cross sectional area have subsequently been devised and validated in adults and children over 1 year of age.

A formula devised by Kim et al. demonstrated good correlation with suctioned gastric volumes in anesthetized children under 1 year of age. It is not known whether a formula derived from data in a cohort of children with clear fluid gastric content resulting from a prolonged overnight fast will perform as well in a cohort of young children who have recently been fed, where, if present, gastric content may be semi-solid or particulate.

The primary aims of this study were to measure GRV of gastric contents measured by naso-gastric aspiration in infants who were breast fed 3 hours prior to general anesthesia. The secondary aim is to correlate predicted GRV using a mathematical formula proposed by Kim et al, to measure GRV by NG aspiration.

Inclusion Criteria:

• Babies born at or after 37 weeks post menstrual age
• Babies born prior to 37 weeks who are now more than 37 weeks corrected post menstrual age (PMA)
• Elective surgery
• Breast fed including expressed breast milk, in isolation or combination with solids or formula.

Exclusion Criteria:

• Babies who are less than 37 weeks PMA,
• Ex-premature babies who are now greater than 37 weeks PMA but who have significant lung, heart, kidney or liver disease.
• Known delayed gastric emptying

Breast fed children under 18 months of age, presenting for elective procedures under general anaesthesia

On reasonable request data can be supplied