Perform CVC successfully in a safe and sterile way for patients is our goal to teach medical students. However, either our teachers or students do not consider our success rate of 67.3% satisfactory, thus we should investigate the performance of students and make improvements. There are two ways to solve this problem. First, increase actual practice in clinical setting. According to the extrapolation of our learning curve shown in Figure 1, in order to increase the success rate of the skill to 80% or higher, students probably would have to perform more than 15 CVCs. This would be a difficult task to achieve. Medical students face limited opportunities to perform CVCs on patients. In the operating theater, patients considered at risk of developing complications are not eligible for students to perform the procedure upon, such as small children, patients with ASA physical status IVE, patients with coagulopathy and those with poor anatomic landmarks. Many patients receive peripheral large bore intravenous lines instead of central catheters for temporary use. As such, the number of CVC opportunities suitable for medical students is limited.
Increase clinical experience in the operating room is difficult, so the alternate solution is to spend more time on simulation training. Despite the major drawback of practicing on manikins is the lack of variations that is different from real patients, students can still improve their dexterity through simulation training. Previous studies showed that simulation-based training improved the central venous catheter insertion and advanced cardiac life support skills of internal medicine residents and medical students [4, 7]. Some students felt awkward using one hand for advancing the needle into the vein. On manikins, they can learn how to hold a puncture needle single-handed to advance the needle into a central vein. Once they have learned it, when they perform CVC on patients, one of the hands advancing needle, another hand either palpating the artery or holding an ultrasound probe to guide the needle into the central vein. This may increase the success rate. After students have placed the puncture needle in the vein, they have to learn how to keep the needle in the vessel steadily. Students should not advance the guidewire with force, since this could easily cause the guidewire kinked. Students should learn how to cut and dilate skin and soft tissues properly, and then they can place the catheter over the guidewire smoothly. We need to focus on the common reasons why previous students failed the procedure and let future students deliberately practice these steps in the simulation center. CVC skills may be acquired more rapidly if students learn sequentially in smaller steps and then combine them into one, seamless performance.
In this study, the complications rate was 7.8%, which was similar to the published rates of iatrogenic mechanical complications associated with the catheterisation of the internal jugular vein (6.3% to 11.8%) and femoral vein (12.8% to 19.4%) [8–11]. Several studies demonstrated that ultrasound-guided CVCs had a significantly higher success rate and lower complications rate than procedures where ultrasound is not used [12–15]. We will incorporate ultrasound-guided CVC teaching into the medical student training.
As this is a retrospective study, it has certain limitations. Firstly, the logbook is a tool for recording student actual clinical performance. Because students recorded the data themselves, it was difficult for students to time the procedure, to count the number of sticks they had done. Therefore, some detailed data were not available in this study. Secondly, the attitude of students was not included. From the logbooks of two medical students, they performed only three CVCs in operating theater. We do not know the reason why. It might be they had low motivation to perform the procedure, they did not have the chance to do it, or the students just did not record the procedure they did in the logbooks. Thirdly, some of the students had a chance to perform multiple needle sticks to find the central vein, whereas this possibility was denied to others. Some supervisors were very cautious about patient safety, because according to Mansfield et al., the complication rate of catheterization increased markedly when a physician attempted more than two needle passes . The presence of different supervisor-student interactions may be a potential explanation for such variability, this is not available either.
In the future, new teaching program will incorporate teaching medical students to use ultrasound for CVC and we will evaluate the skill acquisition on that. Logbooks have been used as tools for assessment of procedural skills . With proper design, both subjective and objective data can be included. We will ask supervisors to record students’ performance at the end of the procedure on the logbooks after communicating with students. This will make the data in the logbooks more complete and accurate. Meantime, students should make a better use of simulation and accelerate the learning curve for skill acquisition. Once their success rate improves, students’ self-reported satisfaction and confidence will improve in return.