Albert R. Robinson

Lung Isolation Using a Laryngeal Mask Airway and a Bronchial Blocker in a Patient With a Recent Tracheostomy

R C E UNG ISOLATION AND one-lung ventilation facilitate intrathoracic operations.1 Bronchial blockers including the rndt wire-guided endobronchial blocker (Cook Critical Care, nc, Bloomington, IN), the Univent torque control blocker Vitaid Ltd, Lewiston, NY), the Cohen Flextip Plus endobronhial blocker (Cook Critical Care, Inc), the Uniblocker (Fuji ystems Corporation, Tokyo, Japan), the Fogarty vascular emolectomy catheter (Edwards Lifesciences, Irvine, CA), and the allinckrodt double-lumen endobronchial tube (Tyco Healthare group LP, Pleasanton, CA) are the typical devices used in hese clinical situations.2-9 Conditions such as anatomic varints, difficult airway, and small stature make certain lung solation techniques relatively contraindicated secondary to the isk or danger associated with placement. There is limited ublished discussion of techniques describing lung isolation in atients with tracheostomies.9-13 Chen et al9 reported placement f a Foley catheter as the bronchial blocker in a patient with a racheostomy. Placement of double-lumen endotracheal tubes ia their tracheostomy sites was described by Coe et al.12 Later, ndros and Lennon13 showed placement of a Univent tube Fuji Systems Corporation, Tokyo, Japan) through a patient’s racheostomy site. This case report describes the combined use f a laryngeal mask airway (LMA) and a bronchial blocker to rovide lung isolation in a patient with a recent tracheostomy. n LMA can be used as an adjunct to create a conduit to place ronchial blockers in patients with difficult airways, especially atients with immature tracheostomies. This approach can be sed for patients with fresh tracheostomies who require singleung ventilation while maintaining continuous ventilation.

Mixed simulators: Augmented physical simulators with virtual underlays

We introduce a taxonomy for mixed simulation focusing on mixed simulators with physical exteriors augmented with virtual underlays for practicing medical procedures such as central venous access (CVA). We used CT and MRI imaging and 3D printing to develop anatomically authentic mixed simulators, i.e., exact physical and/or virtual replicas of their human models. Embedded 6 DOF magnetic sensors monitor tracked instruments during simulated procedures, facilitating after action review or self-debriefing. We implemented automated scoring algorithms that include tracking and grading of near misses. After 28 anesthesia residents trained with the CVA simulator, incidence of pneumothorax and arterial puncture in the simulated environment dropped from 11 % to 7% and 13% to 7%, respectively.

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.

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.

Use of an automated circuit for isolated limb infusion for malignancy

BACKGROUND Isolated limb infusion (ILI) for recurrent or in-transit melanoma is an accepted technique that allows high-dose chemotherapy to be delivered to an extremity with minimal systemic toxicity. Current infusion systems have relied on manual delivery of drugs and circulation of blood during the treatment. Herein, we document our initial results with an automated circuit for ILI as an alternative to the manual technique. METHODS Patients undergoing ILI with an automated circuit for recurrent or advanced malignancy were identified. ILI was performed utilizing a Sarns 8000 roller pump attached to a Cobe 4:1 cardioplegia set with heat exchanger with a total priming volume of 80 ml. Melphalan (7.5 mg/L) and Dactinomycin (75 μg/L) doses which were corrected for ideal body weight were delivered via the infusion circuit after limb temperature reached 38 °C. RESULTS Fourteen lower extremity infusion procedures were performed in 10 patients. Successful infusion procedures were completed in all patients using the automated circuit. Constant flow rates of 50-70 cc/minute were achievable with the automated circuit. Acute toxicity and clinical results were similar to that reported with manual delivery systems. CONCLUSION ILI for advanced malignancy utilizing an automated circuit is feasible and safe. This automated system offers a safe and reliable alternative to the manual infusion technique.