An observational study of gastric contents in pediatric patients with long bone fracture using gastric ultrasound.

Background: The retention of gastric contents at surgery presentation is a risk factor for perioperative aspiration. A preoperative fasting (nil per os; NPO) interval is widely used to reduce this risk, but this approach is based on assumptions about the prevalence of typical gastric emptying rates. We assessed NPO guidelines' reliability with ultrasound (US) imaging and suction in pediatric patients presenting for single long-bone fracture repair after appropriate NPO intervals, when nearly all should have had empty stomachs.

Aims and methods: This prospective cross-sectional observational study comprised 200 pediatric surgical patients. As their NPO times varied by food/drink type, we defined "weighted NPO units" as the lowest multiple of elapsed recommended NPO times between consumption and surgery for each type of food or drink. We used US to image the stomach and its contents before anesthesia induction, followed by gastric suction. We evaluated the relationships between weighted NPO units, US gastric contents grade, opioid analgesic dosage and timing, and suctioned volume.

Results: Despite meeting typical NPO standards (median 14 h fasting), many patients retained nontrivial quantities of gastric contents at surgery. Weighted NPO units did not exhibit statistically-significant relationships with either suctioned volume or US grade. However, suctioned volume did correspond well to US grade.

Conclusion: NPO status may be a less reliable predictor of gastric contents at anesthesia induction in this patient population than has been assumed. Bedside US screening appears to provide more useful information for the planning of airway management.