Point-of-care ultrasound evaluation and puncture simulation of the internal jugular vein by medical students

Central venous access is the cannulation of a central vein via percutaneous puncture [1]. It is indicated in certain medical situations such as the hemodynamic monitoring of critical ill patients and the infusion of medications, parenteral nutrition, or hemodialysis [2].

Central puncture is typically performed at the jugular, subclavian, or femoral vein [3]. In practice, the internal jugular vein (IJV) is a common site, but recent data show that subclavian puncture is associated with lower rates of infection and thrombosis [4].

Traditionally, puncture of a central vein is performed as the “blind” insertion of a needle following anatomical landmarks [5]. Puncture of the IJV for central venous access was first described in 1969 [6]. Since then, various other approaches have been proposed: anterior, central, and posterior approaches [7, 8].

While these traditional techniques (TTs) based on anatomical markers have been validated, they are associated with failure rates ranging from 5 to 40% [3] and complications such as pneumothorax, hematoma, hemothorax, lesions of nerves, and others. These occur at rates between 5 and 19% [9].

For these reasons, ultrasound (US) has been recommended since the 1980s to guide the procedure, optimizing successful cannulation and minimizing complications [10].

Over the last two decades, US equipment has become progressively more compact and accessible, facilitating its use at the point of care. Point-of-care ultrasound (POCUS) is performed and interpreted by the physician in charge wherever the patient is located [11]. Therefore, US is actually an extension of the physical examination, offering the physician a valuable complement to the patient’s propedeutic and monitoring in addition to guiding procedures, thus increasing their safety and efficacy [12, 13].

The use of US for central venous access can considerably reduce its risks and complications [5, 14].

Ultrasound-guided techniques (USGTs) can be quickly assimilated by professionals who have no previous experience. Moureau et al. suggested that supervised training ideally spans 16 to 18 h, although the technique has been mastered in less time [15, 16].

In this study, we aimed to show that medical students can evaluate the IJV and its anatomical variations after rapid and focused training. We also aimed to evaluate the success rate of IJV puncture in simulation following TTs and monitored via US.

Of 105 patients ranging in age from 18 to 89 years, 82 were women.

Five were excluded because of poor image quality, leaving 100 patients included in the analysis.

On the left side, it was most commonly found in the anterior position (36%) and was also found in the anterolateral (31%), anteromedial (31%), lateral (1%), and medial (1%) positions (Table 1). On both sides, the posterior position and its variables were not found.

These data show that medical students can be trained to recognize the anatomy of large vessels in the neck using US after rapid and focused training. Adequate images were obtained from 95% of the patients chosen for evaluation, reinforcing the simplicity and feasibility of the method.

Puncture of the IJV is a procedure often performed in hospitals, emergency departments, and during pre-hospital care for a wide range of indications. Although several studies have shown that USGTs are cost-effective, not only for reducing mechanical complications and infections, but primarily for increasing the success rate and reducing procedure time, it is not used routinely, especially in developing countries [14, 19], given the lack of equipment availability, lack of trained professionals, and other reasons [16].

As found by several others [20–23], great anatomical variability is found between the IJV and the CCA. Variability is also seen between the left and right sides of the same individual (Fig. 4). The IJV is in an anatomical position 48% of the time on the right side and 32% of the time on the left side. Use of TTs assumes that the IJV is in an anatomical position on both sides, but this was observed in fewer than 50% of our patients, combining anterolateral and lateral positions.

Additionally, great variability was found in the caliber of the IJV in our sample, and this is also supported by the literature [17, 21]. In our sample, the IJV was completely collapsed on the right and left sides 20% and 18% of the time, respectively (Fig. 5). Puncturing a collapsed vein is nearly impossible, even if the needle is directed correctly. Another complicating factor is that, in our sample, the IJV was anterior to the CCA 68% of the time. Attempting puncture in this condition can have disastrous consequences because of the risk of reaching the CCA, given that vein collapse amplifies this risk.

We emphasize that in our patients, examination was conducted in a supine position with 0° slope despite the recommendation to position the patient in a Trendelenburg, a suggestion that is not always feasible for a variety of reasons. In this study, contralateral rotation of the neck was used because this position is most frequently recommended in IJV puncture by TTs. However, it has been shown that neck rotation does not interfere with the rate of success and/or reduction of complications when using USGTs [24].

In this study, puncture of the IJV was simulated at the demarcated point, where a TT was theoretically performed (Fig. 1). The success rate using US was determined as well (Fig. 3). Our data show that puncture could reach the IJV 62.5% of the time. Therefore, in 37.5% of the patients (75 of 200 simulations), more than one puncture attempt would be performed, increasing the possibility of complications [25]. The IJV was collapsed in 15 of 125 simulations in which the needle was supposed to reach that vein. Because it is unlikely that puncture is successful with a collapsed vein, we can conclude that the success rate would be 55% for the first attempt, confirming results from studies comparing TTs to USGTs [14, 19].

As suggested by Dinh et al. [26], incorporating training in USGTs in the curriculum for undergraduate medical students is highly desirable and feasible, and this is confirmed by our data. Implementing this and other applications of POCUS in medical schools would ensure that new generations of physicians are naturally empowered, increasing the resoluteness and safety of patient care.

This study is limited by the simulated nature of our procedures; however, actual puncture is not possible for ethical reasons. Also, students performed these procedures after training and without direct supervision, but our objective was to precisely verify the feasibility and simplicity of ultrasonographic visualization of the vessels of the neck after a short period of training. To avoid misinterpretation of the images, all were recorded and reviewed by physicians experienced in POCUS.

These data suggest that training medical students to recognize large neck vessels is a simple, quick, and feasible task and that can be integrated into the undergraduate medical curriculum.