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. 2018 Jun;21(2):137-144.
doi: 10.1007/s40477-018-0292-7. Epub 2018 Mar 21.

The learning curve of sonographic inferior vena cava evaluation by novice medical students: the Pavia experience

Santi Di Pietro  1 , Francesco Falaschi  2 , Alice Bruno  3 , Tiziano Perrone  4 , Valeria Musella  5 , Stefano Perlini  3
Affiliations

The learning curve of sonographic inferior vena cava evaluation by novice medical students: the Pavia experience

Santi Di Pietro et al. J Ultrasound. 2018 Jun.

Abstract
in English, Italian

Purpose: The sonographic evaluation of inferior vena cava diameters and its collapsibility-that is also defined as the caval index-has become a popular way to easily obtain a noninvasive estimate of central venous pressure. This is generally considered an easy sonographic task to perform, and according to the American College of Emergency Physicians (ACEP) Guidelines 25 repetitions of this procedure should be sufficient to reach proficiency. However, little is known about the learning process for this sonographic technique. Therefore, we designed this study to investigate the learning curve of inferior vena cava evaluation.

Methods: We enrolled a sample of ten ultrasound-naïve medical students who received a preliminary training provided by two Junior Emergency Medicine Residents. Following training, each student performed the sonographic task on 25 different patients who were hospitalized in the internal medicine ward. The students' performance was compared with the results obtained by a consultant in internal medicine with extensive experience in point-of-care ultrasound, who repeated the procedure on the same patients (gold standard). In detail, we evaluated the time to complete the task, the quality of the obtained images, and the ability to visually estimate and measure the caval index.

Results: Although most students (9/10) reached the pre-defined level of competence, their overall performance was inferior to the one achieved by the gold standard, with little improvement over time. However, repetition was associated with progressive shortening of the time needed to achieve readable images.

Conclusions: Overall, these findings suggest that, although allowing to obtain a pre-defined competence, 25 repetitions are not enough to reach a good level of proficiency for this technique, that needs a longer training to be achieved.

Scopo: Lo studio ecografico della vena cava inferiore con la misurazione dei diametri e la valutazione della sua collassabilità agli atti respiratori, noto come caval index, si è diffuso come un semplice metodo per stimare in modo non invasivo la pressione venosa centrale. Generalmente questo task ecografico è considerato di semplice esecuzione, e, secondo linee guida dell’American College of Emergency Physicians (ACEP) 25 ripetizioni di questa procedura sarebbero sufficienti a raggiungere la proficiency. Tuttavia, la curva di apprendimento per questa tecnica è stata scarsamente studiata. Per questo abbiamo realizzato questo studio, al fine di analizzare il processo di apprendimento per lo studio ecografico della vena cava inferiore.

Metodi: Abbiamo arruolato un campione di 10 studenti di Medicina senza precedenti esperienze in ecografia. Gli studenti hanno dapprima ricevuto un training preliminare da parte di Specializzandi di Medicina d’Emergenza-Urgenza, e, successivamente, hanno eseguito il task ecografico su 25 pazienti ricoverati presso il reparto di Medicina Interna. Le performance degli studenti sono state confrontate con quelle di un medico strutturato di Medicina Interna con lunga esperienza in ecografia point-of-care, che ha ripetuto la procedura sugli stessi pazienti, fungendo quindi da gold-standard. I parametri analizzati sono stati il tempo per completare la procedura, la qualità delle immagini ottenute e la capacità di stimare visivamente e misurare il caval index.

Risultati: Anche se la maggior parte degli studenti (9/10) hanno raggiunto il livello predefinito di competenza, le loro performance sono state sommariamente inferiori rispetto a quelle del gold-standard, registrando un piccolo trend di miglioramento nei tempi medi per l’esecuzione del task ecografico.

Conclusioni: Questi risultati suggeriscono che, sebbene 25 ripetizioni consentano ad un soggetto inesperto di ottenere un livello pre-definito di competenza, non sembrano però essere sufficienti a raggiungere la proficiency necessaria per questa tecnica, che necessita di un training più lungo.

Keywords: Caval index; Inferior vena cava; Learning curve; Point of care ultrasound; Ultrasound for undergraduates.

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Conflict of interest statement

Conflict of interest

We declare no conflict of interest or financial support for this article.

Ethical approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.

Informed consent

Informed consent was obtained from all individual participants included in the study.

Figures

Fig. 1
Fig. 1
Graphic representation of student’s correct answers to questionnaire before and after the preliminary training Students were overall able to obtain an image in 187 out of 250 cases (75%, P < 0.001 when compared with the gold standard). Image quality was deemed as sufficient (ACEP ≥ 3) in 116/250 cases (46.4%)
Fig. 2
Fig. 2
Gradual attainment of the level of competency over the 25 repetitions. Within the first 5 iterations none of the students reached the pre-set level competency, which was, however, accomplished by 90% of students by the end of the study
Fig. 3
Fig. 3
Median time needed by students to complete the task during the first 13 and the last 12 iterations
See this image and copyright information in PMC

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