SENSITIVITY AND SPECIFICITY AT DETECTING FREE INTRA-ABDOMINAL FLUID BY MEDICAL STUDENTS AFTER AN ABBREVIATED FOCUSSED ASSESSMENT WITH SONOGRAPHY (FAST) COURSE. A NOVEL STUDY USING DIAGNOSTIC PERITONEAL LAVAGE (DPL) TO QUANTIFY AND EVALUATE THE PERFORMANCE OF THE NOVICE ULTRASONOGRAPHER.
Matt J. Kaminsky MD, Elizabeth Gwinn MD, Kim Joseph* MD, Dorion Wiley MD, Andy Dennis DO, Starr Fred MD, Faran Bokhari* MD, Kim Nagy* MD, Cook County Hospital
Introduction: Non-radiologist certification in focussed assessment with sonography in trauma (FAST) and point of care ultrasound has evolved overtime. In general, there has been a trend to fewer minimum certification cases and for formal ultrasound courses being increasingly available to more junior house staff and medical students. Many studies have documented good knowledge acquisition and retention before and after ultrasound courses, however, the performance curve of the novice ultrasonographer in practice can further be explored. We hypothesize that medical students, with directed ultrasound training, would be able to generate proper images of the hepato-renal and spleno-renal fossa components of FAST, as well as the ability to detect a well defined and clinically relevant volume of free intra-abdominal fluid.
Methods: A prospective blinded study was performed at a high volume urban trauma center investigating the performance of 3rd and 4th year medical students with an abbreviated 1 hour video and 1 hour hands on ultrasound course. Novel to this study is the use of patients requiring a diagnostic peritoneal lavage (DPL), for the work up of traumatic injuries, in order to quantify the intra-abdominal volume of fluid. At the time of the DPL procedure, students were assessed for image acquisition of the hepato-renal and spleno-renal, as well as the ability to detect 0, 200, 400, 600, 800 and 1000cc of DPL fluid. Image interpretation was evaluated by an individual certified in FAST to establish the sensitivity and specificity of novice performed FAST.
Results: Between June 2013 and August 2014 over 90 medical students rotating in the trauma department underwent the directed training course. 20 patients requiring DPL were paired with a medical student for assessment of ultrasound skill acquisition. Students evaluated were able to generate an adequate image of the hepato-renal fossa at a rate of 90% with performance rate dropping to 67% for the spleno-renal fossa. The mean volume of DPL fluid to correctly generate an initial positive interpretation by the medical student was 625cc (SD 205cc) for the hepato-renal fossa and a mean volume of 833cc (SD 197cc) for the spleno-renal fossa. A sensitivity of 86.5% (CI 74.2% to 94.4%) and specificity of 93.1% (CI 83.3% to 98.1%) was determined for the hepato-renal fossa. For the spleno-renal fossa the students achieved a sensitivity of 61.1% (CI 35.8% to 82.6%) and specificity of 91.9% (CI 82.2% to 97.3%).
Conclusion: After a limited but directed FAST ultrasound training course, students were able to generate adequate images of the hepato-renal and spleno-renal fossa, with good sensitivity and specificity at detecting free fluid, particularly for the hepato-renal fossa. Short directed training courses in ultrasound are feasible, practical and well received by students with clinically relevant performance achievable. Selective training of the hepato-renal view of FAST should further be investigated for practitioners in forward triage scenarios.
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