The role of gastric ultrasound in anaesthesia for emergency surgery

The timing and technique of anaesthesia are challenging in patients with a history of recent food intake. The presence of gastric contents increases the risk of aspiration, potentially resulting in acute lung injury, pneumonia, or death. Delayed gastric emptying complicates the estimation of aspiration risk. Surprisingly, there are no fasting guidelines for emergency surgery. Point-of-care gastric ultrasound is a time-efficient, cost-efficient and accurate bedside tool with which to estimate residual gastric content and to guide decision-making in airway management and timing of general anaesthesia. This review summarises the prevailing concepts of ultrasound-guided gastric content assessment for emergency surgery. Medline and Embase databases were searched for studies using ultrasound for the evaluation of gastric content in adults scheduled for emergency surgery. Five prospective observational studies representing 793 emergency surgery patients showed that the incidence of ‘full stomach’ was between 18 and 56% at the time of induction. Risk factors for a full stomach before emergency surgery were abdominal or gynaecological/obstetric surgery, high body mass index and morphine consumption. No correlation between preoperative fasting time and the presence of a full/empty stomach was found. No deaths due to aspiration were reported. The preoperative presence of gastric content before emergency surgery is high and the estimates used for clinical management are unreliable. This review demonstrates that gastric ultrasound is a valuable tool for evaluating gastric content. A flow chart for medical decision-making using gastric ultrasound before emergency surgery was developed to assist in clinical decision-making. The validity and practical applicability should be assessed in future studies.