Ultrasound evaluation of soft-tissue foreign bodies by US army medics

Abstract

Objective: The study's primary objective was to determine army medics' accuracy performing bedside ultrasound (US) to detect radiolucent foreign bodies (FBs) in a soft-tissue hand model. Secondary objectives included the assessment of US stand-off pad effects on soft-tissue FB detection rates and assess established FB detectable lower limit size of 2 mm. Methods: Prospective, single blinded, observational study of US-naïve Army medics' abilities utilizing bedside US to detect wooden FBs in a chicken thigh model with or without an US stand-off pad. After a 2 h training period, medics' abilities to detect 1–3 mm FB utilizing a SonoSite®M-Turbo US and 13–6 MHz linear probe were assessed. Results: After a 2 h training period, 28 medics had a sensitivity and specificity of 73% and 78% detecting 1–3 mm FBs utilizing standard US equipment. The medics' sensitivity and specificity were both 78% in detecting radiolucent FBs 2 mm and larger without a stand-off pad. The sensitivity and specificity decreased to 48%, 62%, and 67% when utilizing a stand-off pad to detect 1, 2, and 3 mm soft-tissue FBs. Sub 2 mm detection rates decreased from 82% for 2 mm FB to 64% for 1 mm FBs without utilizing a stand-off pad. Conclusion: Army medics with minimal US experience successfully identified FBs embedded in hand models with accuracies similar to radiologists and emergency medicine physicians. However, radiolucent FB detection sensitivity and specificity decreased in US-naïve Army medics utilizing stand-off pads. In addition, this study reconfirmed the lower limit of FB detection rates at 2 mm. These results support Army medics' utilization of US to evaluate for superficial radiolucent FBs of the hand.

Keywords

• Army medics
• chicken model
• foreign bodies
• stand-off pad
• ultrasound