Interpretation Accuracy and Theoretical Decision Impact of Prehospital Ultrasound for Paramedics - Analysis of a...

Focused, limited-scope prehospital ultrasound (PHUS) has become increasingly feasible for paramedics to learn and implement. However, the impact of ultrasound findings on paramedic clinical decisions has not been well examined. In this pilot program, we investigated the accuracy of paramedic interpretation and theoretical impact of ultrasound findings on clinical decisions in a small rural pilot program of PHUS in the state of New Hampshire.

In this prospective observational cohort study, five experienced paramedics performed 47 total exams during patient care, including focused assessment with sonography in trauma (eFAST) (n = 15), focused pulmonary (n = 20), and cardiac arrest echocardiography (n = 12). Paramedics were instructed to follow existing protocols and not use PHUS findings to change decisions. Paramedics completed online forms post-call, which included their diagnostic exam interpretation and perceived impact of PHUS on treatment, transport, and receiving facility decision if PHUS was integrated into care. The program medical director performed an independent review of the associated PHUS exam image clips and made a "gold standard" interpretation. Then, paramedic interpretations were compared as accurate, indeterminate due to poor window quality, or inaccurate. Statistical differences between the three different exam types were examined using contingency tables.

Among all exam types, 39 (83%) were accurately interpreted with adequate windows, 7 (15%) were indeterminate from incomplete windows, and only one (2%) was truly inaccurate. Paramedics reported that 10 (8%) exams would have impacted their decisions if integrated into care, 55 (46%) would have supported the decision that they made without PHUS, and 54 (45%) would not have impacted their decision. Overall, 32 (63%) pulmonary, 23 (64%) eFAST, and 10 (31%) cardiac exams would support or impact their decisions (p = 0.04).

Trained, experienced paramedics can acquire and accurately interpret focused PHUS exams in the field. Incomplete windows were the most frequent source of interpretation error. Paramedics reported that PHUS findings would support or impact their clinical decisions in the majority of uses, with pulmonary and eFAST providing the most decision support of exams studied. These results support growing evidence that PHUS may support prehospital decisions and patient care in focused, protocolized use cases in rural settings.