A Stepwise Approach to Locating the Antrum During Gastric Ultrasound

Abstract

To the Editor: We read with great interest the excellent work by Sharkey et al.1Sharkey A Mitchell JD Fatima H et al.National Delphi Survey on anesthesiology resident training in perioperative ultrasound.J Cardiothorac Vasc Anesth. 2022; 36: 4022-4031Abstract Full Text Full Text PDF PubMed Scopus (1) Google Scholar on the national Delphi survey of anesthesia resident training in perioperative ultrasonography. We found the outcome of unanimity for gastric ultrasound intriguing. Although the article provided no detailed explanation for why a consensus among experts cannot be reached, it may provide insight into why an objective evaluation with ultrasound is not commonly employed to confirm time-based "empty stomach" information. Most literature focuses on interpreting gastric ultrasound and whether it is a sensitive approach for evaluating stomach contents' status. However, the technical and practical challenge of obtaining a view of the antrum has received little attention. Currently, anesthesiologists are not routinely receiving training in gastric ultrasound, and there is limited information on the learning curve for gastric ultrasound competency. In a cohort study of anesthesiologists who had both prior ultrasound experience and completed a training program, only 50% attained proficiency.2Arzola C Carvalho JCA Cubillos J et al.Anesthesiologists’ learning curves for bedside qualitative ultrasound assessment of gastric content: A cohort study.Can J Anest. 2013; 60: 771-779Crossref PubMed Scopus (74) Google Scholar In another study,3Holtan-Hartwig I Johnsen LR Dahl V et al.Preoperative gastric ultrasound in surgical patients who undergo rapid sequence induction intubation.Trends Anaesth Crit Care. 2021; 38: 30-35Crossref Scopus (1) Google Scholar the investigators, who had completed 50 supervised gastric ultrasound scans, still found that 13% of their examinations were uninterpretable. These studies implied that the field could benefit from gastric ultrasound instruction that makes the skill accessible to novices. Although the antrum is crucial for determining aspiration risk, many trainees need help visualizing it during ultrasonography workshops. Zhou et al.4Zhou L Yang Y Yang L et al.Point-of-care ultrasound defines gastric content in elective surgical patients with type 2 diabetes mellitus: A prospective cohort study.BMC Anesthesiol. 2019; 19: 179Crossref PubMed Scopus (8) Google Scholar found that even the expert anesthesiologists could not visualize the antrum in 6 of 108 adult patients. Patient body mass index, bowel gas, and patient position significantly impact how easy it is to see the antrum. When first learning the technique, it can be challenging, as there is no consistent method for using other anatomic landmarks as a reference point. From our teaching experience, we realize that one of the effective ways to educate trainees on performing gastric scanning for patients is first focusing on locating the antrum using a stepwise approach (Video 1; Figure 1). The key to the “RLSA” (rectus muscles, liver, stomach, antrum) is the stepwise approach. The scanning (Step 1) begins with a curved linear probe placed inferior to the xiphoid process in a transverse view, with the patient in a semi recumbent position. The bilateral rectus muscles and their connecting fascia form a characteristic “bowtie” shape that can establish the patient's midline. (Step 2) Minimizing misperception from the various layers of subcutaneous tissues and fat, the plane of the liver can be quickly identified just below the rectus muscles (ie, depth), and will eventually be seen with continued caudal probe movement down the midline. Continue to move caudally down the liver until a pancake/nugget shape of the stomach is visible. (Step 3) Once the stomach is located, the probe is rotated 90° into the sagittal view to reveal the characteristic image of the cross-section of the antrum at the liver margin (“bullseye” appearance if the patient has an empty stomach). Additionally, we have found that first locating the cross-section antrum with this method and positioning can aid in visualizing the antrum in the right lateral decubitus position. None. eyJraWQiOiI4ZjUxYWNhY2IzYjhiNjNlNzFlYmIzYWFmYTU5NmZmYyIsImFsZyI6IlJTMjU2In0.eyJzdWIiOiI1YTc4OGM5ZWE3NTk0NzJiZjM0MDk0MGNlNjA3ZjJhZiIsImtpZCI6IjhmNTFhY2FjYjNiOGI2M2U3MWViYjNhYWZhNTk2ZmZjIiwiZXhwIjoxNjgwMTM2ODM2fQ.sK5m2TvRoQcDb_D18iYG2Fc1bAJy_d1fqb9DY5QOWT-zMW2SWtF56LGir1IhESVLButMGlDN9DBw3DPeOwuPkyRcNexPHJJBG9ls08SsUtqX9vH7nytPtDoCEwWD8Hg54yjep5_5sDp8pHUnFWSwdcoAB7Eu1HUrvOerzB8rcH_mLMi6zmWVHqrXjqwUGr7xPnL3iQy6KcIV14oSX4KgtM1vZ4QXLZNmfuJf0wykzxioi3kYb9U88n3H9z3yKDDM-QiwQZFhVc30eY49pEPgIWY0x_ZysNv2J93YtJHOY16c4ZIYyDtNT5eiNb3To2ynJufsRkwQ3pi3NDfqQPxuSQ Download .mp4 (5.24 MB) Help with .mp4 files RLSA Stepwise Gastric Ultrasound Approach National Delphi Survey on Anesthesiology Resident Training in Perioperative UltrasoundJournal of Cardiothoracic and Vascular AnesthesiaVol. 36Issue 11PreviewObjective: To establish agreement among nationwide experts through a Delphi process on the key components of perioperative ultrasound and the recommended minimum number of examinations that should be performed by a resident upon graduation.Design: A prospective cross-sectional study.Setting: A survey on multiinstitutional academic medical centers.Participants: Anesthesiology residency program directors and/or experts in perioperative ultrasound.Interventions: A list of components and examinations recommended for anesthesiology resident training in perioperative ultrasound was developed based on guidelines and 2 survey rounds among a steering committee of 10 experts. 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