Portable Ultrasound Device Usage and Learning Outcomes Among Internal Medicine Trainees: A Parallel-Group Randomized Trial

Previous guidelines have recommended increased HUD access for learners,^13,24,35,36 but there have been few investigations that have evaluated the impact of such access on learning POCUS. One previous investigation found that hospitalists who carried HUDs were more likely to identify heart failure on bedside examination.³⁷ In contrast, our study found no improvement in interpretative ability when randomizing interns to carry HUDs for patient care. Notably, interns did not perform more POCUS examinations when given HUDs. We offer several explanations for this finding. First, time-motion studies have demonstrated that internal medicine interns spend less than 15% of their time toward direct patient care.³⁸ It is possible that the demands of being an intern impeded their ability to perform more POCUS examinations on their patients, regardless of HUD access. Alternatively, the interns randomized to no personal access may have used the community device more frequently as a result of the lecture series. Given the cost of HUDs, further studies are needed to assess the degree to which HUD access will improve trainee interpretive ability, especially as more training programs consider the creation of ultrasound curricula.^{10,11,24,39,40}

This study was unique because it followed interns over a year-long course that repeated the same material to assess rates of learning with repeated exposure. Learners improved their scores after the first, but not second, block. Furthermore, the median scores were nearly identical between the first postblock assessment and second preblock assessment (0.81 vs 0.78), suggesting that knowledge was retained between blocks. Together, these findings suggest there may be limitations of traditional lectures that use standardized patient models for practice. Supplementary pedagogies, such as in-the-moment feedback with actual patients, may be needed to promote mastery.^14,35

Despite no formal curriculum, the 2016 intern class (historical control) had learned POCUS to some degree based on their higher assessment scores compared with the 2017 intern class during the preintervention period. Such learning may be informal, and yet, trainees may feel confident in making clinical decisions without formalized training, accreditation, or oversight. As suggested by this study, adding regular didactics or giving trainees HUDs may not immediately solve this issue. For assessment items in which the 2017 interns did not significantly differ from the controls, they nonetheless reported higher confidence in their abilities. Similarly, interns randomized to HUDs less frequently cited a lack of confidence in their abilities, despite similar scores to the no-HUD group. Such confidence may be incongruent with their actual knowledge or ability to safely use POCUS. This phenomenon of misplaced confidence is known as the Dunning–Kruger effect, and it may be common with ultrasound learning.⁴¹ While confidence can be part of a holistic definition of competency,¹⁴ these results raise the concern that trainees may have difficulty assessing their own competency level with POCUS.³⁵

There are several limitations to this study. It was performed at a single institution with limited sample size. It examined only intern physicians because of funding constraints, which limits the generalizability of these findings among medical trainees. Technical ability assessments (including obtaining and interpreting images) were not included. We were unable to track the timing or location of the devices’ usage, and the interns’ self-reported usage rates may be subject to recall bias. To our knowledge, there were no significant lapses in device availability/functionality. Intern physicians in the HUD arm did not receive formal feedback on personally acquired patient images, which may have limited the intervention’s impact.

In conclusion, internal medicine interns who received personal HUDs were not better at recognizing normal/abnormal findings on image assessments, and they did not report performing more POCUS examinations. Since the minority of a trainee’s time is spent toward direct patient care, offering trainees HUDs without substantial guidance may not be enough to promote mastery. Notably, trainees who received HUDs felt more confident in their abilities, despite no objective increase in their actual skill. Finally, interns who received POCUS-related lectures experienced significant benefit upon first exposure to the material, while repeated exposures did not improve performance. Future investigations should stringently track trainee POCUS usage rates with HUDs and assess whether image acquisition ability improves as a result of personal access.