Central venous catheterization using a perfused human cadaveric model: application to surgical education

Simulation-based learning in nephrology

Simulation is a technique to replace and amplify real experiences with guided ones that evoke or replicate substantial aspects of the real world in a fully interactive fashion. In nephrology (a particularly complex specialty), simulation can be used by patients, nurses, residents, and attending physicians alike. It allows one to learn techniques outside the stressful environment of care such as central venous catheter placement, arteriovenous fistula management, learning about peritoneal dialysis, or performing a kidney biopsy. Serious games and virtual reality are emerging methods that show promise. Simulation could also be important in relational aspects of working in a team or with the patient. The development of simulation as a teaching tool in nephrology allows for maintaining high-quality training for residents, tailored to their future practice, and minimizing risks for patients. Additionally, this education helps nephrologists maintain mastery of technical procedures, making the specialty attractive to younger generations. Unfortunately, the inclusion of simulation training programmes faces occasional logistical or funding limitations that universities must overcome with the assistance and innovation of teaching nephrologists. The impact of simulation-based teaching on clinical outcomes needs to be investigated in clinical studies.

Lessons Learned: Large-Scale Perfused Cadaver Training in Three Different Curricular Environments

BACKGROUND

Perfused cadavers are viable training models for operating room surgical skills, increasing fidelity of vascular anatomy, dissection, and tissue handling. In addition, perfused cadavers may have benefits in military medical training environments with a focus on hemorrhage control and vascular access.

OBJECTIVES

We created a large-scale training exercise with perfused cadavers in three different environments and aim to share the curricular design and feedback from the exercise.

METHODS

We conducted a 4-day simulation training exercise with 13 perfused cadavers in 3 different environments: hospital environment, the austere echelons of care environment, and a controlled-settings tent for hemorrhage control and needle decompression training. Through an anonymous online survey and an after-action review (AAR), we elicited feedback on advantages, disadvantages, costs, and comparison to models of porcine and fresh cadavers for procedures and existing courses.

RESULTS

A total of 324 participants were trained with 13 perfused cadavers for over 4 days from a variety of specialties and on different procedures and surgical skills. Based on 130 respondents to the survey and the AAR, perfused cadavers were rated to have realistic arterial bleeding and bleeding control training. In addition, perfused cadavers provided increased realism and fidelity for surgical skills. There were disadvantages of logistical requirements, cleanup, costs, and mobility.

CONCLUSION

Perfused cadavers can be implemented effectively for hemorrhage control training, surgical and procedure skills, and even exercises in austere environments, but require significant logistical and planning considerations. The training value is maximized with a progressive curriculum from hemorrhage control iterations to more invasive surgical procedures, such as thoracotomy and exploratory laparotomy.

Comparing the Utility of Landmark-Palpation Guided to Ultrasound-Guided Teaching Methodologies for Subclavian Central Venous Access Using a Formalin-Embalmed Cadaver Model

Background

Low-risk and realistic simulation strategies are needed to train clinical learners to perform hands-on invasive procedures. This follow-up study compares the utility of landmark-guided palpation-based to ultrasound-guided teaching techniques for subclavian central venous access using formalin-embalmed cadavers.

Methods

The subclavian veins of 3 cadavers were imaged with ultrasound to evaluate vein patency before palpation-based venous access was attempted. Twenty-three first-year medical students were trained to access the subclavian vein using palpation-based techniques. Training involved ten minutes of didactic orientation and ten minutes of hands-on practical instruction using cadavers. Participant confidence was measured using a 10-point Likert scale on pre- and post-training questionnaires. Objective skills testing for each participant included quantifying the number of skin punctures and recording the time elapsed from first skin puncture to fluid flashback into the syringe. Data was analyzed using a generalized linear model (GLM) approach.

Results

Participant confidence significantly increased following training in both ultrasound and palpation training groups across all questionnaire items (P<0.001). The ultrasound group had fewer skin punctures (P<0.001) and fewer failures (1) than the palpation group (6). Participants in the ultrasound group were more confident than those in the palpation group in their ability to locate the vein and select the optimal site for needle access (P<0.05).

Conclusion

Formalin-embalmed cadavers provide a safe, stress-free, and effective means by which to train students in subclavian vein access using both palpation and ultrasound-based techniques. Repeated practice accessing and aspirating fluid from a cadaveric subclavian vein significantly increases trainee confidence, an essential factor in physician performance that may lead to fewer complications. Introducing this type of low-risk and hands-on practice may be beneficial for trainees before they attempt subclavian vein access on live patients.

Efficacy of a perfused cadaver model for simulated trauma resuscitation in advanced surgical skills training

Background

To develop a perfused cadaveric model for trauma surgery simulation, and to evaluate its efficacy in trauma resuscitation advanced surgical skills training.

Methods

Fourteen fourth-year general surgery residents attended this workshop at Siriraj Hospital (Bangkok, Thailand). Inflow and outflow cannulae and a cardiopulmonary bypass pump were used to create the perfusion circuit. Inflow was achieved by cannulating the right common carotid artery, and outflow by cannulation of both the right common femoral artery and the internal jugular vein. Arterial line monitoring was used to monitor resuscitation response and to control perfusion pressure. The perfusion solution comprised saline solution mixed 1:1 with glycerol (50%) and water with red food dye added. Advanced surgical skills during life-threatening injuries and damage control resuscitation operations were practiced starting from the airway to the neck, chest, peripheral vessels, abdomen, and pelvis. Resuscitative endovascular balloon occlusion of the aorta (REBOA) was also practiced. Post-workshop survey questions were grouped into three categories, including comparison with previous training methods; the realism of anatomical correlation and procedures; and, satisfaction, safety, and confidence. All questions and tasks were discussed among all members of the development team, and were agreed upon by at least 90% of experts from each participating medical specialty/subspecialty.

Results

The results of the three main groups of post-workshop survey questions are, as follows: (1) How the training compared with previous surgical training methods—mean score: 4.26/5.00, high score: 4.73/5.00; (2) Realism of anatomical correlation and procedures—mean score: 4.03/5.00, high score: 4.60/5.00; and, (3) Satisfaction, safety, and confidence—mean score: 4.24/5.00, high score: 4.47/5.00.

Conclusion

The developed perfused cadaveric model demonstrated potential advantages over previously employed conventional surgical training techniques for teaching vascular surgery at our center as evidenced by the improvement in the satisfaction scores from students attending perfused cadaveric training compared to the scores reported by students who attended earlier training sessions that employed other training techniques. Areas of improvement included ‘a more realistic training experience’ and ‘improved facilitation of decision-making and damage control practice during trauma surgery’.

An Innovative Biological Model for Ultrasound-Guided Central Venous Access Simulation

INTRODUCTION

Simulation training is an increasingly used method to train medical students in the use of ultrasound guidance for vascular access positioning. Although very efficient for basic training, commercial simulators for vascular access do not reproduce real-life conditions. We developed a biological training model, using porcine liver, and compared it with an existing commercial model.

METHODS

Whole porcine livers were used by perfusing the portal vein system after inferior vena cava clamping. Thirty-three practitioners accustomed to ultrasound-guided procedure were enrolled to perform an ultrasound-guided vascular procedure on both biological and commercial models. Procedure duration was recorded and 10-point scales were used to compare the 2 models regarding image quality, procedure feeling, and similarity with the real-life procedure.

RESULTS

Participants reported a better image quality with the biological model (8.8 ± 1 vs. 7.7 ± 2, P = 0.007) as well as a significant difference in the procedure feeling (8.0 ± 1 vs. 6.9 ± 1.9, P = 0.002). Real-life likeness was significantly better for the biological model (8.4 ± 1.1 vs. 4.5 ± 6, P < 0.0001). Procedure duration was almost 3 times longer using the biological model than the commercial model (209.6 ± 189.0 vs. 59.8 ± 50.1, P < 0.0001).

CONCLUSIONS

This study validates our biological model of porcine's liver as an interesting training model, allowing closer real-life perception than its commercial counterpart. This model could complement and enhance simulation learning.

Improving the quality of training paramedics by means of cadavers - a pilot study

BACKGROUND

Paramedics are authorised to perform emergency procedures, including trauma assessment according to global standards. The aim of the study was to answer the question whether the use of cadavers in teaching practical competencies to medical rescue students, in the field of trauma assessment, is necessary as a supplement to learning in simulated conditions with the use of mannequins.

METHODS

Research included several stages. The first stage was conduction of classes for 27 students in the field of rapid trauma assessment, in accordance with the guidelines of the International Trauma Life Support. In the second stage, a plan of a test in which students had to perform an analogous procedure of rapid trauma assessment, but with the use of cadavers, human unfixed specimens, was prepared. The Delphi method was used to develop and approve checklists, as well as a scale to assess the global correctness of identification of head, torso and limb injuries by medical rescue students.

RESULTS

The identification rate was 76.54% in the head area, 67.90% in the torso area, while in the limb area it equalled 44.45%. A significant difference in scores, compared to the examination performed on a mannequin, was observed (Wilcoxon = 4.541; p = 0.000). The most difficult to make a correct diagnosis were injuries related to a fracture of the proximal end of the femur and a dislocated wrist (only 18.52% of correct answers). The students highly rated the usefulness of the examination, by awarding it an average of 4.76 points (SD ± 0.56) on the Likert scale (0-5).

CONCLUSIONS

The study shows that the use of cadavers to teach practical competencies in the field of trauma assessment to medical rescue students can be an effective supplement to simulated learning. Students could feel the difference between the human body and the mannequin. More research is needed to assess whether realistic simulation translates into objective endpoints, such as the effectiveness of diagnosis in the examination of trauma patients. However, it should be remembered that the introduction of this teaching method is expensive and requires adequate base, as well as the compliance with a number of formal requirements.

The Use of a Novel Perfusion-Based Human Cadaveric Model for Simulation of Dural Venous Sinus Injury and Repair

BACKGROUND

Dural sinus injuries are potentially serious complications associated with acute blood loss. It is imperative that neurosurgery trainees are able to recognize and manage this challenging scenario.

OBJECTIVE

To assess the feasibility of a novel perfusion-based cadaveric simulation model to provide the fundamentals of dural sinus repair to neurosurgical trainees.

METHODS

A total of 10 perfusion-based human cadaveric models underwent superior sagittal sinus (SSS) laceration. Neurosurgery residents were instructed to achieve hemostasis by any method in the first trial and then repeated the trial after watching the instructional dural flap technique video. Trials were timed until hemostasis and control of the region of injury was achieved. Pre- and post-trial questionnaires were administered to assess trainee confidence levels.

RESULTS

The high-flow extravasation of the perfusion-based cadaveric model mimicked similar conditions and challenges encountered during acute SSS injury. Mean ± standard deviation time to hemostasis was 341.3 ± 65 s in the first trial and 196.9 ± 41.8 s in the second trial (P < .0001). Mean trainee improvement time was 144.4 s (42.3%). Of the least-experienced trainees with longest repair times in the initial trial, a mean improvement time of 188.3 s (44.8%) was recorded. All participants reported increased confidence on post-trial questionnaires following the simulation (median pretrial confidence of 2 vs post-trial confidence of 4, P = .002).

CONCLUSION

A perfusion-based human cadaveric model accurately simulates acute dural venous sinus injury, affording neurosurgical trainees the opportunity to hone management skills in a simulated and realistic environment.

Safety Committee of Japanese Society of Anesthesiologists. Practical guide for safe central venous catheterization and management 2017

Central venous catheterization is a basic skill applicable in various medical fields. However, because it may occasionally cause lethal complications, we developed this practical guide that will help a novice operator successfully perform central venous catheterization using ultrasound guidance. The focus of this practical guide is patient safety. It details the fundamental knowledge and techniques that are indispensable for performing ultrasound-guided internal jugular vein catheterization (other choices of indwelling catheters, subclavian, axillary, and femoral venous catheter, or peripherally inserted central venous catheter are also described in alternatives).

Recommendations on the Use of Ultrasound Guidance for Central and Peripheral Vascular Access in Adults: A Position Statement of the Society of Hospital Medicine

PREPROCEDURE

1)We recommend that providers should be familiar with the operation of their specific ultrasound machine prior to initiation of a vascular access procedure. 2)We recommend that providers should use a high-frequency linear transducer with a sterile sheath and sterile gel to perform vascular access procedures. 3)We recommend that providers should use two-dimensional ultrasound to evaluate for anatomical variations and absence of vascular thrombosis during preprocedural site selection. 4)We recommend that providers should evaluate the target blood vessel size and depth during preprocedural ultrasound evaluation.

TECHNIQUES

General Techniques 5) We recommend that providers should avoid using static ultrasound alone to mark the needle insertion site for vascular access procedures. 6)We recommend that providers should use real-time (dynamic), two-dimensional ultrasound guidance with a high-frequency linear transducer for central venous catheter (CVC) insertion, regardless of the provider's level of experience. 7)We suggest using either a transverse (short-axis) or longitudinal (long-axis) approach when performing real-time ultrasound-guided vascular access procedures. 8)We recommend that providers should visualize the needle tip and guidewire in the target vein prior to vessel dilatation. 9)To increase the success rate of ultrasound-guided vascular access procedures, we recommend that providers should utilize echogenic needles, plastic needle guides, and/or ultrasound beam steering when available. Central Venous Access Techniques 10) We recommend that providers should use a standardized procedure checklist that includes the use of real-time ultrasound guidance to reduce the risk of central line-associated bloodstream infection (CLABSI) from CVC insertion. 11)We recommend that providers should use real-time ultrasound guidance, combined with aseptic technique and maximal sterile barrier precautions, to reduce the incidence of infectious complications from CVC insertion. 12)We recommend that providers should use real-time ultrasound guidance for internal jugular vein catheterization, which reduces the risk of mechanical and infectious complications, the number of needle passes, and time to cannulation and increases overall procedure success rates. 13)We recommend that providers who routinely insert subclavian vein CVCs should use real-time ultrasound guidance, which has been shown to reduce the risk of mechanical complications and number of needle passes and increase overall procedure success rates compared with landmark-based techniques. 14)We recommend that providers should use real-time ultrasound guidance for femoral venous access, which has been shown to reduce the risk of arterial punctures and total procedure time and increase overall procedure success rates. Peripheral Venous Access Techniques 15) We recommend that providers should use real-time ultrasound guidance for the insertion of peripherally inserted central catheters (PICCs), which is associated with higher procedure success rates and may be more cost effective compared with landmark-based techniques. 16)We recommend that providers should use real-time ultrasound guidance for the placement of peripheral intravenous lines (PIV) in patients with difficult peripheral venous access to reduce the total procedure time, needle insertion attempts, and needle redirections. Ultrasound-guided PIV insertion is also an effective alternative to CVC insertion in patients with difficult venous access. 17)We suggest using real-time ultrasound guidance to reduce the risk of vascular, infectious, and neurological complications during PIV insertion, particularly in patients with difficult venous access. Arterial Access Techniques 18)We recommend that providers should use real-time ultrasound guidance for arterial access, which has been shown to increase first-pass success rates, reduce the time to cannulation, and reduce the risk of hematoma development compared with landmark-based techniques. 19)We recommend that providers should use real-time ultrasound guidance for femoral arterial access, which has been shown to increase first-pass success rates and reduce the risk of vascular complications. 20)We recommend that providers should use real-time ultrasound guidance for radial arterial access, which has been shown to increase first-pass success rates, reduce the time to successful cannulation, and reduce the risk of complications compared with landmark-based techniques.

POSTPROCEDURE

21) We recommend that post-procedure pneumothorax should be ruled out by the detection of bilateral lung sliding using a high-frequency linear transducer before and after insertion of internal jugular and subclavian vein CVCs. 22)We recommend that providers should use ultrasound with rapid infusion of agitated saline to visualize a right atrial swirl sign (RASS) for detecting catheter tip misplacement during CVC insertion. The use of RASS to detect the catheter tip may be considered an advanced skill that requires specific training and expertise.

TRAINING

23) To reduce the risk of mechanical and infectious complications, we recommend that novice providers should complete a systematic training program that includes a combination of simulation-based practice, supervised insertion on patients, and evaluation by an expert operator before attempting ultrasound-guided CVC insertion independently on patients. 24)We recommend that cognitive training in ultrasound-guided CVC insertion should include basic anatomy, ultrasound physics, ultrasound machine knobology, fundamentals of image acquisition and interpretation, detection and management of procedural complications, infection prevention strategies, and pathways to attain competency. 25)We recommend that trainees should demonstrate minimal competence before placing ultrasound-guided CVCs independently. A minimum number of CVC insertions may inform this determination, but a proctored assessment of competence is most important. 26)We recommend that didactic and hands-on training for trainees should coincide with anticipated times of increased performance of vascular access procedures. Refresher training sessions should be offered periodically. 27)We recommend that competency assessments should include formal evaluation of knowledge and technical skills using standardized assessment tools. 28)We recommend that competency assessments should evaluate for proficiency in the following knowledge and skills of CVC insertion: (a) Knowledge of the target vein anatomy, proper vessel identification, and recognition of anatomical variants; (b) Demonstration of CVC insertion with no technical errors based on a procedural checklist; (c) Recognition and management of acute complications, including emergency management of life-threatening complications; (d) Real-time needle tip tracking with ultrasound and cannulation on the first attempt in at least five consecutive simulation. 29)We recommend a periodic proficiency assessment of all operators should be conducted to ensure maintenance of competency.

Development of cadaver perfusion models for surgical training: an experimental study

PURPOSE

Perfusion techniques on cadavers are heterogeneous and imperfect. The objective of this study was to improve the existing circulation model for surgical simulation on cadavers.

METHODS

We used a three-step experimental approach. The first part of the experiment tested two variables: the type of circuit and the use of a heater for perfusion. The second approach evaluated two parameters: the injection fluid and the type of body conditioning (embalmed or freshly dead prepared using different washing techniques). The third one was an improvement on the best circulation obtained, which focused on the injection fluid. To compare the realism of these different techniques, we constructed a score with realism parameters: the volume of return flow, the presence of peripheral venous return and the perfusion of abdominal arteries.

RESULTS

We found that the use of a heater seemed to improve the perfusion, while performing an arteriovenous bypass did not seem very effective. A correlation rate of 0.84 was found between the realism score and the injected fluid chosen. The best score (4/6) was found for a non-embalmed body with a low-pressure washing technique using a gelatin-based liquid at a concentration of 4 g/L for circulation. Scores obtained using embalmed bodies for both injection fluids for high-pressure washing or for 8-g/L gelatin injection fluid did not exceed 3/6.

CONCLUSIONS

We showed that using a non-embalmed body with low-pressure washing and a 4-g/L gelatin-based fluid was the most effective technique for cadaver perfusion.

A Randomized Controlled Trial using iTClamp, Direct Pressure, and Balloon Catheter Tamponade to Control Neck Hemorrhage in a Perfused Human Cadaver Model

BACKGROUND

Penetrating neck wounds are common in the civilian and military realms. Whether high or low velocity, they carry a substantial morbidity and mortality rate.

OBJECTIVES

We endeavored to ascertain whether the iTClamp is equivalent to direct manual pressure (DMP) and Foley catheter balloon tamponade (BCT).

METHODS

Using a perfused cadaver, a 4.5-cm wound was made in Zone 2 of the neck with a 1-cm carotid arteriotomy. Each of the hemorrhage control modalities was randomized and then applied to the wound separately. Time to apply the device and fluid loss with and without neck motion was recorded.

RESULTS

There was no significant difference between the fluid loss/no movement (p > 0.450) and fluid loss/movement (p > 0.215) between BCT and iTClamp. There was significantly more fluid lost with DMP than iTClamp with no movement (p > 0.000) and movement (p > 0.000). The iTClamp was also significantly faster to apply than the Foley (p > 0.000).

CONCLUSIONS

The iTClamp and BCT were associated with significantly less fluid loss than DMP in a perfused cadaver model. The iTClamp required significantly less time to apply than the BCT. Both the iTClamp and the BCT were more effective than simple DMP. The iTClamp offers an additional option for managing hard-to-control bleeding in the neck.

The Development of a Novel Perfused Cadaver Model With Dynamic Vital Sign Regulation and Real-World Scenarios to Teach Surgical Skills and Error Management

The landscape of graduate medical education has changed dramatically over the past decade and the traditional apprenticeship model has undergone scrutiny and modifications. The mandate of the 80-hour work-week, the introduction of integrated residency programs, increased global awareness about patient safety along with financial constraints have spurred changes in graduate educational practices. In addition, new technologies, more complex procedures, and a host of external constraints have changed where and how we teach technical and procedural skills. Simulation-based training has been embraced by the surgical community and has quickly become an essential component of most residency programs as a method to add efficacy to the traditional learning model. The purpose of this paper is twofold: (1) to describe the development of a perfused cadaver model with dynamic vital sign regulation, and (2) to assess the impact of a curriculum using this model and real world scenarios to teach surgical skills and error management. By providing a realistic training environment our aim is to enhance the acquisition of surgical skills and provide a more thorough assessment of resident performance. Twenty-six learners participated in the scenarios. Qualitative data showed that participants felt that the simulation model was realistic, and that participating in the scenarios helped them gain new knowledge, learn new surgical techniques and increase their confidence performing the skill in a clinical setting. Identifying the importance of both technical and nontechnical skills in surgical education has hastened the need for more realistic simulators and environments in which they are placed. Team members should be able to interact in ways that allow for a global display of their skills thus helping to provide a more comprehensive assessment by faculty and learners.

Techniques of cadaver perfusion for surgical training: a systematic review

PURPOSE

The objective of this study was to identify the most appropriate cadaver perfusion techniques for surgical training through a systematic review with a description of the protocols used.

METHODS

The search strategy included PubMed and reference tracking. Studies were identified by searching the electronic Medline databases. The search concepts included perfusion, cadavers and simulation training, and the protocol used is reported. This resulted in a qualitative review of 12 articles out of 250 articles consulted. We collected all the important data from these 12 articles.

RESULTS

Regarding the characteristics of the studies and the declotting or perfusion techniques, the results were heterogeneous. Indeed, in several studies, a good deal of information was unclear or insufficiently precise, making it unfeasible to summarize the data. The methods used were not sufficiently explicit and detailed. However, a majority of the fresh cadavers used tap water for declotting. Perfusion, type of fluid, number of pumps, pressure, pulsatility, and arterial or venous approaches differed greatly. Only two studies fulfilled five of our six realism criteria for surgical simulation.

CONCLUSIONS

This systematic review provided an overview of all the different cadaver perfusion techniques. It could be used to establish a reference method of a simulation model.

Assessment of ultrasound-guided procedures in preclinical years

Medical graduates entering residency often lack confidence and competence in procedural skills. Implementation of ultrasound (US)-guided procedures into undergraduate medical education is a logical step to addressing medical student procedural competency. The objective of our study was to determine the impact of an US teaching workshop geared toward training medical students in how to perform three distinct US-guided procedures. Cross-sectional study at an urban academic medical center. Following a 1-h didactic session, a sample of 11 students out of 105 (10.5 %) were asked to perform three procedures each (total 33 procedures) to establish a baseline of procedural proficiency. Following a 1-h didactic session, students were asked to perform 33 procedures using needle guidance with ultrasound to establish a baseline of student proficiency. Also, a baseline survey regarding student opinions, self-assessment of skills, and US procedure knowledge was administered before and after the educational intervention. After the educational workshop, students' procedural competency was assessed by trained ultrasound clinicians. One-hundred-and-five third-year medical students participated in this study. The average score for the knowledge-based test improved from 46 % (SD 16 %) to 74 % (SD 14 %) (p < 0.05). Students' overall confidence in needle guidance improved from 3.1 (SD 2.4) to 7.8 (SD 1.5) (p < 0.05). Student assessment of procedural competency using an objective and validated assessment tool demonstrated statistically significant (p < 0.05) improvement in all procedures. The one-day US education workshop employed in this study was effective at immediately increasing third-year medical students' confidence and technical skill at performing US-guided procedures.

Standardized, Interdepartmental, Simulation-Based Central Line Insertion Course Closes an Educational Gap and Improves Intern Comfort with the Procedure

Central line placement is a common procedure, routinely performed by junior residents in medical and surgical departments. Before this project, no standardized instructional course on the insertion of central lines existed at our institution, and few interns had received formal ultrasound training. Interns from five departments participated in a simulation-based central line insertion course. Intern familiarity with the procedure and with ultrasound, as well as their prior experience with line placement and their level of comfort, was assessed. Of the 99 interns in participating departments, 45 per cent had been trained as ofOctober 2015. Forty-one per cent were female. The majority (59.5%) had no prior formal ultrasound training, and 46.0 per cent had never placed a line as primary operator. Scores increased significantly, from a precourse score mean of 13.7 to a postcourse score mean of 16.1, P < 0.001. All three of the self-reported measures of comfort with ultrasound also improved significantly. All interns reported the course was “very much” helpful, and 100 per cent reported they felt “somewhat” or “much” more comfortable with the procedure after attendance. To our knowledge, this is the first hospital-wide, standardized, simulation-based central line insertion course in the United States. Preliminary results indicate overwhelming satisfaction with the course, better ultrasound preparedness, and improved comfort with central line insertion.

A comparison of a homemade central line simulator to commercial models

BACKGROUND

Simulation is quickly becoming vital to resident education, but commercially available central line models are costly and little information exists to evaluate their realism. This study compared an inexpensive homemade simulator to three commercially available simulators and rated model characteristics.

MATERIALS AND METHODS

Seventeen physicians, all having placed >50 lines in their lifetime, completed blinded central line insertions on three commercial and one homemade model (made of silicone, tubing, and a pressurized pump system). Participants rated each model on the realism of its ultrasound image, cannulation feel, manometry, and overall. They then ranked the models based on the same variables. Rankings were assessed with Friedman's and post hoc Conover's tests, using alphas 0.05 and 0.008 (Bonferroni corrected), respectively.

RESULTS

The models significantly differed (P < 0.0004) in rankings across all dimensions. The homemade model was ranked best on ultrasound image, manometry measurement, cannulation feel, and overall quality by 71%, 67%, 53%, and 77% of raters, respectively. It was found to be statistically superior to the second rated model in all (P < 0.003) except cannulation feel (P = 0.134). Ultrasound image and manometry measurement received the lowest ratings across all models, indicating less realistic simulation. The cost of the homemade model was $400 compared to $1000-$8000 for commercial models.

CONCLUSIONS

Our data suggest that an inexpensive, homemade central line model is as good or better than commercially available models. Areas for potential improvement within models include the ultrasound image and ability to appropriately measure manometry of accessed vessels.

Evaluation of Percutaneous First Annular Pulley Release: Efficacy and Complications in a Perfused Cadaveric Study

PURPOSE

Trigger finger is the most common entrapment tendinopathy, with a lifetime risk of 2% to 3%. Open surgical release of the flexor tendon sheath is a commonly performed procedure associated with a high rate of success. Despite reported success rates of over 94%, percutaneous trigger finger release (PFTR) remains a controversial procedure because of the risk of iatrogenic digital neurovascular injury. This study aimed to evaluate the safety and efficacy of traditional percutaneous and ultrasound (US)-guided first annular (A1) pulley releases performed on a perfused cadaveric model.

METHODS

First annular pulley releases were performed percutaneously using an 18-gauge needle in 155 digits (124 fingers and 31 thumbs) of un-embalmed cadavers with restored perfusion. A total of 45 digits were completed with US guidance and 110 digits were completed without it. Each digit was dissected and assessed regarding the amount of release as well as neurovascular, flexor tendon, and A2 pulley injury.

RESULTS

Overall, 114 A1 pulleys were completely released (74%). There were 38 partial releases (24%) and 3 complete misses (2%). No significant flexor tendon injury was seen. Longitudinal scoring of the flexor tendon was found in 35 fingers (23%). There were no lacerations to digital nerves and one ulnar digital artery was partially lacerated (1%) in a middle finger with a partial flexion contracture that prevented appropriate hyperextension. The ultrasound-assisted and blind PTFR techniques had similar complete pulley release and injury rates.

CONCLUSIONS

Both traditional and US-assisted percutaneous release of the A1 pulley can be performed for all fingers. Perfusion of cadaver digits enhances surgical simulation and evaluation of PTFR beyond those of previous cadaveric studies. The addition of vascular flow to the digits during percutaneous release allows for Doppler flow assessment of the neurovascular bundle and evaluation of vascular injury.

CLINICAL RELEVANCE

Our cadaveric data align with those of published clinical investigations for percutaneous A1 pulley release.

Introducing a Fresh Cadaver Model for Ultrasound-guided Central Venous Access Training in Undergraduate Medical Education

Introduction

Over the past decade, medical students have witnessed a decline in the opportunities to perform technical skills during their clinical years. Ultrasound-guided central venous access (USG-CVA) is a critical procedure commonly performed by emergency medicine, anesthesia, and general surgery residents, often during their first month of residency. However, the acquisition of skills required to safely perform this procedure is often deficient upon graduation from medical school. To ameliorate this lack of technical proficiency, ultrasound simulation models have been introduced into undergraduate medical education to train venous access skills. Criticisms of simulation models are the innate lack of realistic tactile qualities, as well as the lack of anatomical variances when compared to living patients. The purpose of our investigation was to design and evaluate a life-like and reproducible training model for USG-CVA using a fresh cadaver.

Methods

This was a cross-sectional study at an urban academic medical center. An 18-point procedural knowledge tool and an 18-point procedural skill evaluation tool were administered during a cadaver lab at the beginning and end of the surgical clerkship. During the fresh cadaver lab, procedure naïve third-year medical students were trained on how to perform ultrasound-guided central venous access of the femoral and internal jugular vessels. Preparation of the fresh cadaver model involved placement of a thin-walled latex tubing in the anatomic location of the femoral and internal jugular vein respectively.

Results

Fifty-six third-year medical students participated in this study during their surgical clerkship. The fresh cadaver model provided high quality and lifelike ultrasound images despite numerous cannulation attempts. Technical skill scores improved from an average score of 3 to 12 (p<0.001) and procedural knowledge scores improved from an average score of 4 to 8 (p<0.001).

Conclusion

The use of this novel cadaver model prevented extravasation of fluid, maintained ultrasound-imaging quality, and proved to be an effective educational model allowing third-year medical students to improve and maintain their technical skills.

Ultrasound-guided procedures in medical education: a fresh look at cadavers

Demand for bedside ultrasound in medicine has created a need for earlier exposure to ultrasound education during the clinical years of undergraduate medical education. Although bedside ultrasound is often used for invasive medical procedures, there is no standardized educational model for procedural skills that can provide the learner a real-life simulated experience. The objective of our study was to describe a unique fresh cadaver preparation model, and to determine the impact of a procedure-focused ultrasound training session. This study was a cross-sectional study at an urban academic medical center. A sixteen-item questionnaire was administered at the beginning and end of the session. Fifty-five third year medical students participated in this 1-day event during their surgical clerkship. Students were trained to perform the following ultrasound-guided procedures: internal jugular vein cannulation, femoral vein cannulation femoral artery cannulation and pericardiocentesis. Preparation of the fresh cadaver is easily replicated and requires minor manipulation of cadaver vessels and pericardial space. Fifty-five medical students in their third year participated in this study. All of the medical students agreed that US could help increase their confidence in performing procedures in the future. Eighty percent (95 % CI 70-91 %) of students felt that there was a benefit of learning ultrasound-based anatomy in addition to traditional methods. Student confidence was self-rated on a five-point Likert scale. Student confidence increased with statistical significance in all of the skills taught. The most dramatic increase was noted in central venous line placement, which improved from 1.95 (SD = 0.11) to 4.2 (SD = 0.09) (p < 0.001). The use of fresh cadavers for procedure-focused US education is a realistic method that improves the confidence of third year medical students in performing complex but critical procedures.

A high-volume trauma intensive care unit can be successfully staffed by advanced practitioners at night

PURPOSE

It remains unknown whether critically ill trauma patients can be successfully managed by advanced practitioners (APs). The purpose of this study was to examine the impact of night coverage by APs in a high-volume trauma intensive care unit (ICU) on patient outcomes and care processes.

MATERIALS AND METHODS

During the study period, our ICU was staffed by APs during the night shift (7 pm-7 am) from Sunday to Wednesday and by resident physicians (RPs) from Thursday to Saturday. On-call trauma fellows and attending surgeons in house supervised both APs and RPs. Patient outcomes and care processes by APs was compared with those admitted by RPs.

RESULTS

A total of 289 patients were identified between July 2013 and February 2014. Median lactate clearance rate within 24 hours of admission was similar between study groups (10.0% vs 9.1%; P = .39). Advanced practitioners and RPs transfused patients requiring massive transfusion with a similar blood product ratio (packed red blood cell:fresh frozen plasma) (2.1:1 vs 1.7:1; P = .32). In a multiple logistic regression analysis, AP coverage was not associated with any clinical outcome differences.

CONCLUSIONS

Our data suggest that, with adequate supervision, a high-volume trauma ICU can be safely staffed by APs overnight.

Pressurized Cadaver Model in Cardiothoracic Surgical Simulation

Simulation is increasingly recognized as an integral aspect of thoracic surgery education. A number of simulators have been introduced to teach component cardiothoracic skills; however, no good model exists for numerous essential skills including redo sternotomy and internal mammary artery takedown. These procedures are often relegated to thoracic surgery residents but have significant negative implications if performed incorrectly. Fresh tissue dissection is recognized as the gold standard for surgical simulation, but the lack of circulating blood volume limits surgical realism. Our aim is to describe the technique of the pressurized cadaver for use in cardiothoracic surgical procedures, focusing on internal mammary artery takedown.