Shallow-angle needle guide for ultrasound-guided internal jugular venous catheterization: A randomized controlled crossover simulation study (CONSORT)

Background Needle guides for ultrasound-guided internal jugular venous catheterization facilitate successful cannulation. The ability of a needle guide to prevent a posterior vein wall injury which may secondarily induce lethal complications, is unknown. Previous studies showed that a shallow angle of approach may reduce the incidence of posterior wall injuries. We developed a novel needle guide with a shallow angle of approach for ultrasound-guided venous catheterization and examined whether this needle guide reduces the incidence of posterior wall injuries compared to a conventional needle guide and free-hand placement in a simulated vein. Methods This study was a randomized crossover-controlled trial. The primary outcome was the rate of posterior vein wall injuries. Participants had a didactic lecture about three ultrasound-guided techniques using the short-axis out-of-plane approach, including free-hand (P-free), a commercial needle guide (P-com), and a novel needle guide (P-sha). The view inside a simulated vein was recorded during venipuncture. Results Thirty-five residents participated in this study. Posterior vein wall injuries occurred in 66% using P-free, 60% using P-com, and 0% using P-sha (p< 0.01). There was no significant difference in the incidence of posterior vein wall injuries between P-free and P-com. Conclusions Use of a shallow angle of approach needle guide resulted in a lower rate of posterior vein injuries during venipuncture of a simulated vein compared with other techniques using a steeper angle techniques.


Development of a shallow angle needle guide to prevent mechanical complications during central venous catheterization (A simulation study)
Study protocol Background・ Objectives Ultrasound guidance during central venous catheterization is associated with high success rates and low mechanical complication rates and is recognized as the "gold standard" technique. The Japan Medical Safety Research Organization reported "Analysis of deaths related to the complications of Central Venous Catheterization (2017)". In this report, about half of the procedures were performed using ultrasound-guidance. The expert committee commented "Real-time ultrasound-guided technique has a pitfall that could lead to serious complications. The operator should receive simulator training in advance".
Needle guides have been developed to assist operators during ultrasound guided venous catheterization. Commercially available needle guides are still not popular because of difficultly in handling with a fixed needle holder. A previous study of a needle navigation system showed that a shallow angle of approach of the needle may reduce the incidence of posterior vein wall injuries. We postulated that the mechanical complication rate may be related to the needle's angle of approach. In this study we will develop a new needle guide to assure a shallow angle of approach for internal jugular venous catheterization. The final goal is contributing to safe conduct of ultrasound-guided central venous catheterization.
Commercially available needle guides may increase the success rate but a new needle guide should be made to prevent mechanical complications. Until now, it was thought that increasing the success rate will reduce the complication rate. However, even if the success rate increases, complications still occur. This is because there was a lack of consideration of pitfalls associated with the ultrasound guided procedure.

Recruitmen t of Particip an ts ( F ir st-year re side nts at Kyo rin Un iver sity Ho spital)
Ultrasound-guided CVC Seminar Lecture for basic skills and simulation training in ultrasound-guided CVC Test for ultrasound-guided CVC procedure 1. Free-hand short-axis out-of-plane approach 2. A commercial needle guide for out-of-plane approach 3. A novel shallow angle needle guide After simulation training, all participants performed each of the 3 approaches using the simulator Data collection Posterior vein wall injury rate, success rate, number of needle passes till success, time for the procedure, unanticipated arterial injuries. A questionnaire to evaluate comfort with the procedure and the preferred procedure using a 5-point Likert scale.
Demographic data collection from participants Experience with CVC and ultrasound guidance

Background
Ultrasound guidance during central venous catheterization is associated with high success rates and low mechanical complication rates, and has been recognized as the "gold standard" technique. In our hospital, applicants listen to a didactic lecture for patient safety and an ultrasound-guided central venous catheterization hands-on seminar to obtaining permission to perform CVC. Ultrasound guidance has the benefit of observing the internal jugular vein and the common carotid artery while handling the needle. This benefit leads to a low complication rate compared to the anatomical landmark technique (1). However, sufficient training is required to perform safe central venous catheterization using ultrasound guidance. The operator with poor skills for ultrasound guidance may cause serious complications.
Recently, needle guides have been developed to assist operators during ultrasound guided venous catheterization, in which the needle trajectory is set by the guide while advancing toward the target vein. A novel ultrasound device equipped needle navigation technology was developed based on detecting a magnetic field (2). The needle navigation technology was reported to yield a high success rate and reduce the rate of posterior wall injuries (3). However, our previous study showed that the needle navigation technology did not lead to a reduction of all complications (rate of posterior wall injuries). The study showed that the angle of approach may be related to the rate of posterior wall injuries. Use of a shallow angle of approach using the needle navigation technology decreased the rate of posterior wall injuries, but a steep angle of approach did not. The navigation technology can assist operators to perform the shallow angle of approach. However, ultrasound devices equipped with needle navigation technology are not in widespread use and are not sold in Japan.

Objective
We developed a new needle guide to assure a shallow angle of approach for internal jugular venous catheterization. In this study, we evaluate the success rate and rate of posterior vein wall injuries comparing the newly developed needle guide, a conventional commercial needle guide, and the free hand method using a simulated internal jugular vein.

Research participants
Participants will be first-year residents who are training in Kyorin University hospital. We conduct a seminar for ultrasound-guided central venous catheterization seminar every year. The participants will be recruited from the seminar as volunteers. Their demographic data will be collected using questionnaires, including prior experience with CVCs, number of cases, experience with ultrasound-guided CVC, and having a CVC license in the institution. Exclusion criteria is previous experience with CVC using a needle guide (the questionnaire was performed after the seminar) (questionnaire is shown in the appendix).

Methods
The following three methods are compared: 1. Free-hand short-axis out-of-plane approach (method 1) 2. A commercial needle guide for out-of-plane approach (method 2) 3. A novel shallow angle needle guide (method 3) After simulation training, all participants perform each of the three approaches using the simulator, and their performance is evaluated. An endoscopic view inside the simulated vessel cannot be seen by participants but is recorded for later review. The video recordings are sequentially numbered, but this number is later randomized by computer to maintain anonymity. The sequence for each participant performing each technique is randomly decided using a random number table. The blinding and allocations are done by a person who does not participate in the trial. The technique used and individual identification are concealed for the evaluation. Two senior physicians who will not participate in the test, observe the recorded videos and evaluate whether the procedure is performed successfully or not.

Outcome
The primary outcome of this study is the rate of posterior vein wall injuries. Secondary outcomes include success rate, number of needle passes till success, time for the procedure, and unanticipated arterial injuries. A questionnaire is given to participants to evaluate comfort and the preferred procedure using a 5-point Likert scale (5: very comfortable with the procedure, 1: uncomfortable with the procedure) (questionnaire form in appendix).

Number of participants
We plan to include fifty junior residents as participants for the following reason: A previous study showed that incidence of posterior vin wall injuries was 41% using a steep angle of approach and 9 % with a shallow angle (4). The sample size required for 80% power at ɑ = 0.05 was estimated to be thirty-four participants. Fifty participants are included to account for exclusions and being a preliminary study.

Simulator, research environment
The simulated internal jugular vein is connected to a water tank through a tube to maintain pressure at 10 cm H2O, which is monitored by a pressure transducer. The simulated carotid artery is pressurized to 50 cm H20 using the same method. An endoscope is inserted into the simulated internal jugular vein and an interior view of the vessel is recorded during the procedure. After each procedure, the participant waits at least 15 minutes as a washout period before performing the next procedure.
9. Equipment ① Endoscopic video system (owned by the Department of Anesthesiology) ② Commercial needle guide AccuSITE™ (Civco Co., USA) (owned by the department) ③ Novel needle guide with a shallow angle of approach (owned by the department).
The needle guide was created using 3D modeling software, 3D Builder (Microsoft Co., USA), and was made of nylon using a 3D print service (DMM.make Co., Japan) (Figures 1, 2). Posterior wall puncture rate when operators use the novel needle guide with a shallow angle of approach will be significantly lower than when using the two other techniques.
13.Data anonymization: The data will be collected using an identification number instead of participant names and create a correspondence table for managing the data.
14. Ethical considerations: This is not a clinical study, but a simulator study. Participants are recruited as volunteers. Written informed consent will be obtained from all participants. We are disclosing research information (in the announcement form "Call for study participants") and participant rights (being able to stop participating at any time). The advantage to the participants is taking the seminar for