Perioperative pulmonary aspiration of gastric contents is a serious complication of anaesthesia and is associated with high morbidity and mortality. It can result in severe pneumonia requiring mechanical ventilator support in up to one-third of patients with a mortality of 5%, representing up to 9% of all anaesthesia-related deaths. The severity of the resulting respiratory compromise is thought to be related to both the volume and nature of the aspirate, with particulate matter carrying the highest risk. Preoperative fasting guidelines help limit the risk in elective patients with minimal co-morbidities. However, fasting intervals are not applicable or reliable in urgent or emergency surgeries or for patients with certain medical conditions. One of the main risk factors for aspiration is the presence of gastric content. The critical volume threshold of gastric fluid that by itself increases aspiration risk is controversial, but healthy, fasted patients frequently have residual gastric volumes (GVs) of up to 1.5 ml/kg without significant aspiration risk.

In anaesthesiology and acute care medicine, there is a growing interest in bedside evaluation of gastric ‘fullness’ to assess pulmonary aspiration risk. With the advent of portable ultrasound machines, performing point-of-care ultrasound has become relatively easy and feasible. Gastric ultrasound examination is finding a place as a point-of-care tool for aspiration risk assessment. It can identify the nature of the gastric content, i.e. empty, clear fluid and solid and when clear fluid is present, its volume can be quantified.

The objective is to determine the correlation between fasting times and gastric content and estimated gastric volume in patients presenting for elective surgery and also to see if the gastric contents and gastric volume are any different in patients with conditions which supposedly predispose them to delayed gastric emptying like diabetes, chronic kidney disease and obesity compared to those without such conditions.