Evaluation of Point-of-Care Ultrasound in a Helicopter Emergency Medical Service Program

Abstract

Objective

Point-of-care ultrasound (POCUS) in the prehospital setting has rapidly expanded, including helicopter emergency medical services (HEMS). A more robust understanding of the use of prehospital POCUS and its impact on patient management is needed. The purpose of this study is to: 1) evaluate the applications of prehospital POCUS examinations, 2) assess physician accuracy in interpretation and the acceptability of the quality of performed exams, and 3) evaluate self-reported alterations in patient management.

Methods

This is a single-center, retrospective, observational cohort study of adult patients aged >18 years transported via HEMS from March 1, 2018 to April 7, 2023, at a single academic medical center. Exclusion criteria were: patients aged <18 years of age and of vulnerable populations (e.g., prisoners, pregnant women), studies with missing data (e.g., medical record numbers), and studies which were not submitted for quality assurance. All flight physicians were trained in prehospital POCUS and required to complete a standardized worksheet following the completion of each examination. Images and worksheets were reviewed weekly and assigned a score for interpretation (e.g., true positive) and whether the exam was acceptable for quality (e.g., yes/no). A second blinded reviewer interpreted all studies. An agreement analysis (Cohen's kappa) was calculated for each variable. McNemar testing was used to assess differences in the distribution of binary measures. Demographic information was obtained for each study participant.

Results

In total, 242 patients received POCUS for a total of 364 examinations by 26 unique users. Focused cardiac (40.4%) and thoracic (32.4%) exams were most commonly performed. Overall accuracy and acceptability for all exams performed were 97.6% and 96.1%, respectively. The accuracy of interpretation between raters demonstrated high agreement (89.2%; K=0.81, 95% CI 0.74-0.88). Acceptability of image quality was also high between raters (95.0%; K=0.38, 95% CI 0.10-0.65) without significant disagreement (p=0.25). Users self-reported alterations in patient management in 75.6% of cases (n=183), most commonly by improving diagnostic certainty (n=131, 71.6%) and altering medical management (n=62, 33.9%).

Conclusion

Focused cardiac and thoracic examinations were the most commonly performed POCUS examinations. Prehospital POCUS can be performed accurately by flight physicians with acceptable image quality. Users frequently reported improved diagnostic accuracy when utilizing prehospital POCUS.