Visualization Improves Supraclavicular Access to the Subclavian Vein in a Mixed Reality Simulator.

BACKGROUND: We investigated whether visual augmentation (3D, real-time, color visualization) of a procedural simulator improved performance during training in the supraclavicular approach to the subclavian vein, not as widely known or used as its infraclavicular counterpart. METHODS: To train anesthesiology residents to access a central vein, a mixed reality simulator with emulated ultrasound imaging was created using an anatomically authentic, 3D-printed, physical mannequin based on a computed tomographic scan of an actual human. The simulator has a corresponding 3D virtual model of the neck and upper chest anatomy. Hand-held instruments such as a needle, an ultrasound probe, and a virtual camera controller are directly manipulated by the trainee and tracked and recorded with submillimeter resolution via miniature, 6 degrees of freedom magnetic sensors. After Institutional Review Board approval, 69 anesthesiology residents and faculty were enrolled and received scripted instructions on how to perform subclavian venous access using the supraclavicular approach based on anatomic landmarks. The volunteers were randomized into 2 cohorts. The first used real-time 3D visualization concurrently with trial 1, but not during trial 2. The second did not use real-time 3D visualization concurrently with trial 1 or 2. However, after trial 2, they observed a 3D visualization playback of trial 2 before performing trial 3 without visualization. An automated scoring system based on time, success, and errors/complications generated objective performance scores. Nonparametric statistical methods were used to compare the scores between subsequent trials, differences between groups (real-time visualization versus no visualization versus delayed visualization), and improvement in scores between trials within groups. RESULTS: Although the real-time visualization group demonstrated significantly better performance than the delayed visualization group on trial 1 (P = .01), there was no difference in gain scores, between performance on the first trial and performance on the final trial, that were dependent on group (P = .13). In the delayed visualization group, the difference in performance between trial 1 and trial 2 was not significant (P = .09); reviewing performance on trial 2 before trial 3 resulted in improved performance when compared to trial 1 (P < .0001). There was no significant difference in median scores (P = .13) between the real-time visualization and delayed visualization groups for the last trial after both groups had received visualization. Participants reported a significant improvement in confidence in performing supraclavicular access to the subclavian vein. Standard deviations of scores, a measure of performance variability, decreased in the delayed visualization group after viewing the visualization. CONCLUSIONS: Real-time visual augmentation (3D visualization) in the mixed reality simulator improved performance during supraclavicular access to the subclavian vein. No difference was seen in the final trial of the group that received real-time visualization compared to the group that had delayed visualization playback of their prior attempt. Training with the mixed reality simulator improved participant confidence in performing an unfamiliar technique.

Expanding role of perioperative transesophageal echocardiography in the general anesthesia practice and residency training in the USA.

PURPOSE OF REVIEW: To review the perioperative use of noncardiac transesophageal echocardiography in anesthesiology and to explore the current mechanisms of teaching and certification. RECENT FINDINGS: Anesthesiologists frequently use echocardiography in many noncardiac situations with potential impact on outcomes. Certification has evolved to include those who use echocardiography in noncardiac situations. More advanced teaching tools have been developed for the learning of diagnostic and monitoring modality. SUMMARY: Transesophageal echocardiography can have many helpful uses in perioperative patient care. This study summarizes many noncardiac uses, certification, and echocardiography education for anesthesiologists.

New frontiers in aortic therapy: focus on deep hypothermic circulatory arrest.

There is currently a paradigm shift in the conduct of adult aortic arch repair. Although deep hypothermic circulatory arrest has been the classic perfusion platform for adult aortic arch repair, recent developments have challenged this aortic arch paradigm. There has been a gradual clinical drift towards moderate, and even mild, hypothermic circulatory arrest combined with antegrade cerebral perfusion. This paradigm shift appears to be associated with equivalent clinical outcomes, and in certain settings, with improved outcomes. The advent of endovascular therapy has challenged even further the concept that circulatory arrest is required for adult aortic arch repair. These dramatic advances have resulted in the emergence of an international aortic arch surgery study group that aims to advance this dynamic field through consensus statements, meta-analysis, clinical database analysis, prospective registries, and randomized controlled trials.

A mixed-reality part-task trainer for subclavian venous access.

INTRODUCTION: Mixed-reality (MR) procedural simulators combine virtual and physical components and visualization software that can be used for debriefing and offer an alternative to learn subclavian central venous access (SCVA). We present a SCVA MR simulator, a part-task trainer, which can assist in the training of medical personnel. METHODS: Sixty-five participants were involved in the following: (1) a simulation trial 1; (2) a teaching intervention followed by trial 2 (with the simulator's visualization software); and (3) trial 3, a final simulation assessment. The main test parameters were time to complete SCVA and the SCVA score, a composite of efficiency and safety metrics generated by the simulator's scoring algorithm. Residents and faculty completed questionnaires presimulation and postsimulation that assessed their confidence in obtaining access and learner satisfaction questions, for example, realism of the simulator. RESULTS: The average SCVA score was improved by 24.5 (n=65). Repeated-measures analysis of variance showed significant reductions in average time (F=31.94, P<0.0001), number of attempts (F=10.56, P<0.0001), and score (F=18.59, P<0.0001). After the teaching intervention and practice with the MR simulator, the results no longer showed a difference in performance between the faculty and residents. On a 5-point scale (5=strongly agree), participants agreed that the SCVA simulator was realistic (M=4.3) and strongly agreed that it should be used as an educational tool (M=4.9). CONCLUSIONS: An SCVA mixed simulator offers a realistic representation of subclavian central venous access and offers new debriefing capabilities.

Retrospective computed tomography mapping of intrapleural air may demonstrate optimal window for ultrasound diagnosis of pneumothorax.

INTRODUCTION: When a pneumothorax exists, free air should rise to the most nondependent region within the chest. Current ultrasound (US) examination methodologies may exclude visualization of these areas that may limit the sensitivity of the examination. This retrospective study uses computed tomography (CT) scans to precisely evaluate where free air within the thorax occurs and correlates this location with a presumably optimal US interrogation window. METHODS: A total of 94 CT scans of patients with a pneumothorax in a single institution from December 2006 to January 2010 were examined. The borders and volumes of each pneumothorax were precisely measured by a radiologist. Logistic regression was used to determine the relationship between volume and location of intrapleural air at specified areas of the hemithorax. Sensitivities relating location of intrapleural air at a specific landmark and side of thorax were calculated. RESULTS: All but 3 of the pneumothoraces extended to the sternum. In all, 83 patients demonstrated a pneumothorax between rib interspaces 3 and 6 (mean pneumothorax volume 300.4 mL, 95% confidence interval [CI] 217.4-383.3), and 11 patients did not (mean pneumothorax volume 4.5 mL, 95% CI 1.7-7.3; P < .0001). The cumulative sensitivity for the presence of intrapleural air at rib interspaces 3 to 6 along the sternal border was 88%. This was consistent regardless of the side of hemithorax (right 91% and left 86%). CONCLUSION: The CT scans demonstrate that intrapleural air most often collects along the mediastinum between ribs 3 and 6 on either side of the chest. Although no USs were performed in this retrospective study, one may infer that a parasternal approach along rib interspaces 3 to 6 is an easy and sensitive window to diagnose pneumothorax with US.

Continuous transthoracic echocardiography in a 93-year-old patient with hypertrophic cardiomyopathy during electroconvulsive therapy.

Electroconvulsive therapy (ECT) is the treatment of choice for patients with a major depression disorder who have failed antidepressant therapy. Patients with hypertrophic cardiomyopathy (HCM) may have dynamic obstruction to left ventricular (LV) outflow. The effects on myocardial function during ECT and pretreatment with antihypertensive agents in patients with HCM and LV outflow tract obstruction gradients are unknown. We report the first use of continuous transthoracic echocardiography during ECT in a patient with HCM. We confirmed an outflow tract obstruction and showed a decrease in LV outflow tract gradients. Continuous transthoracic echocardiography monitoring using Doppler echocardiography during ECT is feasible.