Gastric Point of Care Ultrasound in Adults: Image Acquisition and Interpretation

Summary

This protocol introduces two methods for image acquisition in gastric ultrasonography. Additionally, tips are provided for interpreting this information to assist in medical decision-making.

Abstract

Over the past two decades, diagnostic point-of-care ultrasound (POCUS) has emerged as a rapid and non-invasive bedside tool for addressing clinical inquiries related to gastric content. One emerging concern pertains to patients about to undergo sedation and/or endotracheal intubation: the elevated risk of aspiration from the patient's stomach contents. Aspiration of gastric contents into the lungs poses a serious and potentially life-threatening complication. This occurs more frequently when the stomach is considered "full" and can be affected by the techniques employed for airway management, making it potentially preventable. To mitigate the risk of peri-procedural aspiration, two distinct medical specialties (anesthesiology and critical care medicine) have independently developed techniques to utilize ultrasonography for identifying patients requiring "full stomach" precautions. Due to these separate specialties, the work of each group remains relatively unfamiliar outside its respective field. This article presents descriptions of both techniques for gastric ultrasound. Furthermore, it explains how these approaches can complement each other when one of them falls short. Regarding image acquisition, the article covers the following topics: indications and contraindications, selection of the appropriate probe, patient positioning, and troubleshooting. The article also delves into image interpretation, complete with example images. Additionally, it demonstrates how one of the two techniques can be employed to estimate gastric fluid volume. Lastly, the article briefly discusses medical decision-making based on the findings of this examination.

Introduction

Pulmonary aspiration of gastric contents can cause pneumonitis, pneumonia, and even death¹. Higher volume, the presence of particulate matter, and higher acidity of aspirate have been shown to increase the severity of this scenario. Numerous factors help guide a clinician in assessing the risk of aspiration, including comorbid diseases that may slow gastric emptying times, mechanical gastrointestinal obstruction, and timing of the last oral intake. Historically, the latter relies solely on an assessment of the patient's history, which can be unreliable and inaccurate. In addition, clinician judgment has been shown to be poor to fair at diag....

Protocol

All procedures performed in this study involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. The exams can be performed using either a sector array (sometimes colloquially referred to as a "phased array") or a low-frequency curvilinear transducer based on the sonographers' preference. For the figures and scans, a curvilinear probe was use.......

Discussion

As stated previously, the primary purpose of gastric ultrasound is to evaluate gastric contents and assess risk before airway management or procedural sedation. The provided protocol outlines two main methods to capture images of the gastric antrum and body, aiding in this risk assessment. Additionally, reviewing the representative results section assists gastric sonographers in developing image interpretation skills. While a comprehensive discussion of medical decision-making is beyond this protocol's scope, this manusc.......

Materials

Name	Company	Catalog Number	Comments
High Frequency Ultrasound Probe (HFL38xp)	SonoSite (FujiFilm)	P16038
Low Frequency Ultrasound Probe (C35xp)	SonoSite (FujiFilm)	P19617
SonoSite X-porte Ultrasound	SonoSite (FujiFilm)	P19220
Ultrasound Gel	AquaSonic	PLI 01-08