Written by Clay Smith
Being NPO is not synonymous with having an empty stomach. Even with a median NPO time of almost 6 hours, 69% still had a full stomach on bedside ultrasound.
Why does this matter?
We know from the anesthesia literature that, “NPO status for liquids and solids is not an independent predictor of major complications or aspiration.” So, let’s say we follow the hospital policy and keep them NPO for 6 hours. This should guarantee an empty stomach, right?
NPO doesn’t mean empty stomach
This was a prospective study of children with pending sedation and varying NPO times who underwent bedside gastric ultrasound to determine if any solid material was present or liquid >1.2mL/kg (defined as “full stomach”). Of the 107 children with good images, 69% of fasting children, median fasting time 5.8 hours, were still found to have a full stomach, based on the study definition. As fasting time increased, odds of a full stomach was less. They were unable to predict whether the stomach would be empty based on time of fasting. A strength of the study was the local pediatric POCUS director confirmed the ultrasound findings, being blinded to their bedside interpretation and all clinical information, with good inter-rater agreement (kappa, 0.74). Assuming we can trust this single-center, single sonographer study, this means fasting time is not a great measure of whether the stomach will be empty. Even if we wait the recommended 6 hours (not that it makes a difference anyway), it doesn’t guarantee the stomach will be empty.
“Full Stomach” Despite the Wait: Point-of-Care Gastric Ultrasound at the Time of Procedural Sedation in the Pediatric Emergency Department. Acad Emerg Med. 2018 Oct 29. doi: 10.1111/acem.13651. [Epub ahead of print]
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