Ultrasound Identification of Diaphragm by Novices Using ABCDE Technique

Background and Objectives In this study, we examined the consistency, rapidity, and reproducibility of the ABCDE technique for diaphragm identification. Operators using this method place the probe at the Anterior axillary line, watch for Breathing (lung sliding), and then move the probe Caudally to identify the Diaphragm for Examination. Methods A convenience sample of 100 patients was recruited from the preadmission clinic. Two novice operators each scanned the diaphragm using a linear ultrasound transducer in B-mode. Both operators completed the examination on all participants using the ABCDE technique, their times were averaged, and clinical success was defined as identification of the diaphragm in less than 2 minutes. Results An average of 33.7 seconds was taken to scan and identify the right hemidiaphragm (RD) (median, 25 seconds; 95% confidence interval, 28.8–38.5 seconds) with a 98% clinical success ratio, and an average of 46.9 seconds was taken to identify the left hemidiaphragm (LD) (median, 39.5 seconds; 95% confidence interval, 40.2–53.6 seconds) with a 97% clinical success ratio. In patients with a body mass index (BMI) of less than 30 kg/m2, a 100% success ratio was seen when scanning the RD and 97% when scanning the LD. For those with a BMI of 30 kg/m2 or greater, a 94% success rate was seen when scanning the RD and 97% when scanning the LD. No clinically significant differences were found between the times required for scanning either side of the diaphragm, regardless of the BMI. Conclusions The ABCDE technique demonstrates a fast, reliable, and simple method in which ultrasound can be used to visualize the diaphragm. Accepted for publication September 2, 2017. Address correspondence to: Ban C.H. Tsui, MD, Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, 300 Pasteur Dr, H3582, Stanford, CA 94305 (e-mail: bantsui@stanford.edu). This work was attributable to the Department of Anesthesiology and Pain Medicine, University of Alberta, Edmonton, Alberta, Canada. B.C.H.T. is supported by a Clinical Scholar Award from the Alberta Heritage Foundation for Medical Research, Alberta, Canada; and J.K. is supported in part by an Alberta Health Services Surgery Strategic Clinical Network Summer Surgical Research Studentship Award, Alberta, Canada. The authors declare no conflict of interest. Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal's Web site (www.rapm.org). Copyright © 2018 by American Society of Regional Anesthesia and Pain Medicine.

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