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/m, a 100% success ratio was seen when scanning the RD and 97% when scanning the LD. For those with a BMI of 30 kg/m 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.