Development and Validation of a Mixed-Reality Simulator for Reducing Biopsy Core Deviation During Simulated Freehand Systematic Prostate Biopsy.

INTRODUCTION: We describe the development and validation of a mixed-reality prostate biopsy (PBx) simulator with built-in guidance aids and real-time 3-dimensional visualization. METHODS: We evaluated our simulator during one-on-one training sessions with urology residents and attendings from 2018 to 2022. Participants performed freehand, side-fire, double-sextant transrectal ultrasound-guided systematic prostate biopsy (sPBx). After a baseline assessment (first set of 12 biopsy cores), participants trained for 25 minutes with visualization and cognitive aids activated. Training was followed by an exit set of 12 biopsy cores without visualization or cognitive aids and afterward, subjective assessment by trainees of the simulator. Deviation is the shortest distance of the center of a core from its intended template location. RESULTS: Baseline deviations (mean ± SD) for residents (n = 24) and attendings (n = 4) were 13.4 ± 8.9 mm and 8.5 ± 3.6 mm ( P < 0.001), respectively. Posttraining deviations were 8.7 ± 6.6 mm and 7.6 ± 3.7 mm ( P = 0.271), respectively. Deviations between baseline and exit were decreased significantly for residents ( P < 0.001) but not for attendings ( P = 0.093). Overall feedback from participants was positive. Confidence in performing a PBx increased in novices after training ( P = 0.011) and did not change among attendings ( P = 0.180). CONCLUSIONS: A new PBx simulator can quantify and improve accuracy during simulated freehand sPBx while providing visualization and graphical feedback. Improved simulated sPBx accuracy could lead to more even distribution of biopsy cores within the prostate when performed in clinical settings, possibly reducing the high risk of missing an existing lesion and thus decreasing the time to initiating treatment, if indicated.

Micro-Ultrasound Guided Transperineal Prostate Biopsy: A Clinic-Based Procedure.

Prostate cancer is the most common solid malignancy in men and requires a biopsy for diagnosis. This manuscript describes a freehand micro-ultrasound guided transperineal technique performed under local anesthesia, which maintains accuracy, keeps patients comfortable, has low adverse events, and minimizes the need for disposables. Prior micro-ultrasound-guided transperineal techniques required general or spinal anesthesia. The key steps described in the protocol include (1) the placement of the local anesthesia, (2) micro-ultrasound imaging, (3) and the visualization of the anesthetic/biopsy needle while uncoupled from the insonation plane. A retrospective review of 100 patients undergoing this technique demonstrated a 68% clinically significant cancer detection rate. Pain scores were prospectively collected in a subset of patients (N = 20) and showed a median procedural pain score of 2 out of 10. The 30 day Grade III adverse event rate was 3%; one of these events was probably related to the prostate biopsy. Overall, we present a simple, accurate, and safe technique for performing a micro-ultrasound-guided transperineal prostate biopsy.

Impact of Simulation on Critical Care Fellows' Electroencephalography Learning.

Introduction Continuous electroencephalography (EEG) is an important monitoring modality in the intensive care unit and a key skill for critical care fellows (CCFs) to learn. Our objective was to evaluate with CCFs an EEG educational curriculum on a web-based simulator. Methods This prospective cohort study was conducted at a major academic medical center in Florida. After Institutional Review Board approval, 13 CCFs from anesthesiology, surgery, and pulmonary medicine consented to take an EEG curriculum. A 25-item EEG assessment was completed at baseline, after 10 EEG interpretations with a neurophysiologist, and after 10 clinically relevant EEG-based simulations providing clinical EEG interpretation hints. A 50-minute tutorial podcast was viewed after the baseline assessment. Main assessment outcomes included multiple outcomes related to web-based simulator performance: percent of hints used, percent of first words on EEG interpretation correct, and percent hint-based EEG interpretation score correct, with higher scores indicating more correct answers. Participants completed a 25-item EEG assessment before (baseline) and after the web-based simulator. Results All 13 CCFs completed the curriculum. Between scenarios, there were differences in percent of hints used (F9,108 = 11.7, p < 0.001), percent of first words correct (F9,108 = 13.6, p < 0.001), and overall percent hint-based score (F9,108 = 14.0, p < 0.001). Nonconvulsive status epilepticus had the lowest percent of hints used (15%) and the highest hint-based score (87%). Overall percent hint-based score (mean across all scenarios) was positively correlated with change in performance as the number of correct answers on the 25-item EEG assessment from before to after the web-based simulator activity (Spearman's rho = 0.67, p = 0.023). Conclusions A self-paced EEG interpretation curriculum involving a flipped classroom and screen-based simulation each requiring less than an hour to complete significantly improved CCF scores on the EEG assessment compared to baseline.

A Comparison of Central Venous Access to the Internal Jugular Vein and Two Standard Approaches to the Subclavian Vein: A Study of Cross-Sectional Areas Using Computed Tomography Scans.

Introduction The supraclavicular approach to the subclavian vein has been cited as having many advantages to the infraclavicular approach, including a larger short-axis cross-sectional area, a greater margin of safety, and fewer complications. Methods To examine whether a larger short-axis cross-sectional area of the subclavian vein at the supraclavicular fossa is a potential explanation for the reduction in attempts with the supraclavicular approach seen in a previous study, we examined computed tomography scans from 50 patients (24 M, 26 F). The short-axis cross-sectional areas of the subclavian vein at the mid-clavicular line, the subclavian vein in the supraclavicular fossa, and the internal jugular vein at the level of the thyroid cartilage were calculated. Results The internal jugular vein short-axis cross-sectional area was significantly larger than the subclavian vein short-axis cross-sections measured at each location. We found no difference between the short-axis cross-sectional areas of the subclavian vein or when comparing measurements as a factor of gender, age, or race. Weight had a significant relationship to the short-axis cross-sectional area of the internal jugular vein and subclavian vein at the mid-clavicular vein. Conclusions On supine computed tomographic imaging, the subclavian vein short-axis cross-section was not larger in the supraclavicular fossa than the mid-clavicular line. The short-axis cross-sectional area of the subclavian vein at the supraclavicular fossa does not appear to contribute to the decrease in attempts to access it. Weight, but not necessarily height, appears to be correlated with central vein size.

Simulation Use in Outreach Setting: A Novel Approach to Building Sustainability.

SUMMARY STATEMENT: Simulation is a well-studied teaching tool for multidisciplinary teamwork, crisis resource management, and communication skills. These attributes are essential for successful international medical missions, which include healthcare providers with different familiarities with the outreach environment and each team member's role. However, immersive simulation remains underused in similar settings. Our team designed a simulation-based curriculum that focuses on multidisciplinary teamwork and crisis resource management skills. In this commentary, we describe its implementation during high-risk cleft care outreach missions conducted by the Global Smile Foundation. We discuss the importance of a simple, feasible, and flexible platform to successfully overcome the limitations of time and resources inherent to outreach mission work while addressing the clinical and geographic needs specific to each site. We highlight challenges, including unpredictability of the outreach environment, a language barrier, and the short duration of missions. Finally, we offer a roadmap for groups involved in similar global health efforts.

Manual Conservation of Supplemental Oxygen in Low-Resource Settings During the COVID-19 Pandemic.

SUMMARY STATEMENT: Using a simulated adult COVID-19 patient with hypoxemia, we investigated whether caregivers interrupting oxygen flow by manually occluding oxygen tubing with pliers during exhalation can conserve oxygen while maintaining oxygenation. Oxygen pinching reduced oxygen use by 51% to 64%, maintained simulated oxygen saturation between 88% and 90%, and increased simulated average alveolar partial pressure of oxygen from a room air baseline of approximately 131 to 294-424 mm Hg compared with 607 mm Hg with 10 liters per minute (LPM) continuous oxygen flow. Simulation provided a methodology to rapidly evaluate a technique that has begun to be used with COVID-19 patients in low-resource environments experiencing an acute oxygen shortage.

Attitude is everything: keep probe pitch neutral during side-fire prostate biopsy. A simulator study.

OBJECTIVES: To develop and validate on a simulator a learnable technique to decrease deviation of biopsied cores from the template schema during freehand, side-fire systematic prostate biopsy (sPBx) with the goal of reducing prostate biopsy (PBx) false-negatives, thereby facilitating earlier sampling, diagnosis and treatment of clinically significant prostate cancer. PARTICIPANTS AND METHODS: Using a PBx simulator with real-time three-dimensional visualization, we devised a freehand, pitch-neutral (0°, horizontal plane), side-fire, transrectal ultrasonography (TRUS)-guided sPBx technique in the left lateral decubitus position. Thirty-four trainees on four Canadian and US urology programmes learned the technique on the same simulator, which recorded deviation from the intended template location in a double-sextant template as well as the TRUS probe pitch at the time of sampling. We defined deviation as the shortest distance in millimeters between a core centre and its intended template location, template deviation as the mean of all deviations in a template, and mastery as achieving a template deviation ≤5.0 mm. RESULTS: All results are reported as mean ± sd. The mean absolute pitch and template deviation before learning the technique (baseline) were 8.2 ± 4.1° and 8.0 ± 2.7 mm, respectively, and after mastering the technique decreased to 4.5 ± 2.7° (P = 0.001) and 4.5 ± 0.6 mm (P < 0.001). Template deviation was related to mean absolute pitch (P < 0.001) and increased by 0.5 mm on average with each 1° increase in mean absolute pitch. Participants achieved mastery after practising 3.9 ± 2.9 double-sextant sets. There was no difference in time to perform a double-sextant set at baseline (277 ± 102 s) and mastery (283 ± 101 s; P = 0.39). CONCLUSION: A pitch-neutral side-fire technique reduced template deviation during simulated freehand TRUS-guided sPBx, suggesting it may also reduce PBx false-negatives in patients in a future clinical trial. This pitch-neutral technique can be taught and learned; the University of Florida has been teaching it to all Urology residents for the last 2 years.

The RITE of Passage: Learning Styles and Residency In-Service Training Examination (RITE) Scores.

Introduction The objective of the pilot study was to determine the association between learning preferences and improvement in the American Academy of Neurology Residency In-Service Training Examination (RITE) scores from postgraduate year 2 (PGY-2) to postgraduate year 3 (PGY-3) in neurology residents. Methods Neurology residents at the University of Florida were approached to participate, and their consent was obtained. VARK inventory, representing four modalities (visual, aural, read/write, kinesthetic) of learning preferences, was completed by participants. Participants could pick more than one modality. The number of responses in each sensory domain was recorded, with higher numbers indicating stronger preference. Residents' performance on the RITE was recorded for PGY-2 and PGY-3. Results Seventeen residents completed the VARK inventory and 16 had data for RITE. Residents demonstrated overall positive change in RITE from PGY-2 to PGY-3 (mean change = 6%; 95%CI: 4%, 9%). The median number of responses was highest for the kinesthetic domain (median = 7, range = 1-12), followed by visual (median = 6, range = 2-12), aural (median = 4, range = 1-10), and read/write (median = 4, range = 1-10). Among VARK domains, the number of responses in read/write had the strongest correlation with mean change in RITE performance from PGY-2 to PGY-3 (r = 0.45; 95%CI: -0.08, 0.78); residents in the high read/write group (number of response above median) had greater mean change in RITE performance (9%; 95%CI: 6%, 12%) while those in the low read/write group showed little to no increase in RITE from PGY-2 to PGY-3 (2%; 95%CI: -1%, 6%). Conclusions Higher VARK survey responses in the read/write domain were related to greater change in RITE scores from PGY-2 to PGY-3. These findings seem intuitively obvious considering the format of the RITE. These pilot data permit further investigation of individual resident learning preference and how it relates to test performance. By understanding a resident's learning style, both educators and the resident will have an awareness of areas that need to be improved to be successful, which may be via remedial curricula and self-study activities.

Visualized Prostate Biopsy: An Intuitive Three-Dimensional User Interface for Systematic and Targeted Biopsy.

Background: Prostate biopsy false negative percentages are 21% to 47% and 16% to 30% for systematic and fused biopsy, respectively. An intuitive three-dimensional (3D) observed user interface may help reduce these percentages by providing real-time guidance and feedback during transrectal or transperineal biopsy. Materials and Methods: We track the moving prostate (including template locations and regions of interest), the transrectal ultrasound (TRUS) probe, and the biopsy device to construct a 3D environment. Users observe, aim, sample, and receive feedback in real time. Using a simulator with simulated TRUS, 48 participants performed freehand systematic prostate biopsy with traditional TRUS guidance and afterward with visualized prostate biopsy (vPBx). Results: During simulated biopsy, vPBx reduced the false negative percentage for a 0.5-mL spherical apical lesion from 52% to 2% (p < 0.001). Conclusions: Preliminary results during simulated systematic biopsy warrant retrofitting the vPBx to actual TRUS equipment as a step toward clinical trials with patients.

Simulation-Based Assessment Identifies Longitudinal Changes in Cognitive Skills in an Anesthesiology Residency Training Program.

OBJECTIVES: We describe observed improvements in nontechnical or "higher-order" deficiencies and cognitive performance skills in an anesthesia residency cohort for a 1-year time interval. Our main objectives were to evaluate higher-order, cognitive performance and to demonstrate that simulation can effectively serve as an assessment of cognitive skills and can help detect "higher-order" deficiencies, which are not as well identified through more traditional assessment tools. We hypothesized that simulation can identify longitudinal changes in cognitive skills and that cognitive performance deficiencies can then be remediated over time. METHODS: We used 50 scenarios evaluating 35 residents during 2 subsequent years, and 18 of those 35 residents were evaluated in both years (post graduate years 3 then 4) in the same or similar scenarios. Individual basic knowledge and cognitive performance during simulation-based scenarios were assessed using a 20- to 27-item scenario-specific checklist. Items were labeled as basic knowledge/technical (lower-order cognition) or advanced cognitive/nontechnical (higher-order cognition). Identical or similar scenarios were repeated annually by a subset of 18 residents during 2 successive academic years. For every scenario and item, we calculated group error scenario rate (frequency) and individual (resident) item success. Grouped individuals' success rates are calculated as mean (SD), and item success grade and group error rates are calculated and presented as proportions. For all analyses, α level is 0.05. RESULTS: Overall PGY4 residents' error rates were lower and success rates higher for the cognitive items compared with technical item performance in the operating room and resuscitation domains. In all 3 clinical domains, the cognitive error rate by PGY4 residents was fairly low (0.00-0.22) and the cognitive success rate by PGY4 residents was high (0.83-1.00) and significantly better compared with previous annual assessments (P < 0.05). Overall, there was an annual decrease in error rates for 2 years, primarily driven by decreases in cognitive errors. The most commonly observed cognitive error types remained anchoring, availability bias, premature closure, and confirmation bias. CONCLUSIONS: Simulation-based assessments can highlight cognitive performance areas of relative strength, weakness, and progress in a resident or resident cohort. We believe that they can therefore be used to inform curriculum development including activities that require higher-level cognitive processing.

SMMARTS: An Open Architecture Development Platform for Modular, Mixed, and Augmented Reality Procedural and Interventional Simulators.

INTRODUCTION: Different simulators often share elements, resulting in different laboratories doing redundant work. This can lead to higher development and acquisition costs, proprietary, incompatible technology, lack of interoperability, and large inventories that reduce accessibility to the benefits of simulation. Simulation technology can become more affordable and scalable with open architecture and modular design. We describe the System of Modular Mixed and Augmented Reality Tracking Simulators (SMMARTS) open architecture, rapid development platform for designing and building modular procedural and guided-intervention simulators. METHODS: A modular stand provides mechanical indexing (registration) of a modular anatomical block representing the anatomy relevant to the simulated intervention. A software development kit (SDK) integrated with the hardware (stand and hand-held tracked tools such as a needle and ultrasound probe) facilitates software development. The SMMARTS SDK at https://github.com/UF-CSSALT/SMMARTS-SDK developed in Unity Technologies' Unity game engine includes Arduino microcontroller and NDI's 6 degrees of freedom tracking connectivity along with software tools such as a replayer, user interface templates, 3D visualization of the virtual counterparts of physical elements, scoring monitors, cognitive aids, common error messages, and Experience Application Programming Interface compatibility. RESULTS: We used SMMARTS to develop 9 different simulators internally (instructor-less central venous access currently deployed to Iraq, prostate biopsy, epidural loss-of-resistance, ventriculostomy, pterygopalatine fossa block, lumbar/chronic pain blocks, chest tube insertion) and externally (intravenous access). DISCUSSION: As a living tool, SMMARTS now has sufficient functionality and benefits that we can share it to help clinicians and engineers focus more on content specific to learning objectives rather than back-end tasks.

An online, interactive, screen-based simulator for learning basic EEG interpretation.

OBJECTIVE: Develop and pilot test a simulator that presents ten commonly encountered representative clinical contexts for trainees to learn basic electroencephalogram (EEG) interpretation skills. METHODS: We created an interactive web-based training simulator that allows self-paced, asynchronous learning and assessment of basic EEG interpretation skills. The simulator uses the information retrieval process via a free-response text box to enhance learning. Ten scenarios were created that present dynamic (scrolling) EEG tracings resembling the clinical setting, followed by questions with free-text answers. The answer was checked against an accepted word/phrase list. The simulator has been used by 76 trainees in total. We report pilot study results from the University of Florida's neurology residents (N = 24). Total percent correct for each scenario and average percent correct for all scenarios were calculated and correlated with most recent In-training Examination (ITE) and United States Medical License Examination (USMLE) scores. RESULTS: Neurology residents' mean percent correct scenario scores ranged from 27.1-86.0% with an average scenario score of 61.2% ± 7.7. We showed a moderately strong correlation r = 0.49 between the ITE and the average scenario score. CONCLUSION: We developed an online interactive EEG interpretation simulator to review basic EEG content and assess interpretation skills using an active retrieval approach. The pilot study showed a moderately strong correlation r = 0.49 between the ITE and the average scenario score. Since the ITE is a measure of clinical practice, this is evidence that the simulator can provide self-directed instruction and shows promise as a tool for assessment of EEG knowledge.

Does the Technique for Assessing Loss of Resistance Alter the Magnitude of Epidural Needle Tip Overshoot?

INTRODUCTION: Postdural puncture headache due to accidental dural puncture is a consequence of excessive needle tip overshoot distance after entering the epidural space via a loss of resistance (LOR) technique. We are not aware of any quantitative comparison of the magnitude of needle tip overshoot (distance traveled by the needle tip beyond the point where LOR can be discerned) for the various LOR assessment techniques that are taught. Such a comparison may provide insight into contributing factors of accidental dural puncture and associated postdural puncture headache. METHODS: A custom-built simulator was used to evaluate the following 3 LOR assessment techniques: incremental needle advancement, intermittent LOR assessment (II); continuous needle advancement, high-frequency intermittent LOR assessment (CI); and continuous needle advancement, continuous LOR assessment (CC). RESULTS: There were significant mean differences in maximum overshoot past a virtual LOR plane due to technique (F(2,124) = 79.31, P < 0.001) (Fig. 2). Specifically, maximum overshoot was greater with technique II [mean = 3.8 mm, 95% confidence interval (CI) = 3.4-4.3] versus either CC (mean = 1.9 mm, 95% CI = 1.5-1.8, P < 0.001) or CI (mean = 1.4 mm, 95% CI = 0.9-2.3, P < 0.001). Differences in maximum overshoot between CC and CI were not statistically different (P = 0.996). Maximum overshoot was greater at 4 cm (mean = 3.0 mm, 95% CI = 2.6-3.4) compared with 5 cm (mean = 2.3 mm, 95% CI = 2.0-2.5, P = 0.044), 6 cm (mean = 2.0 mm, 95% CI = 1.9-2.2, P = 0.054), 7 cm (mean = 1.9 mm, 95% CI = 1.7-2.1, P = 0.002), and 8 cm (mean = 1.8 mm, 95% CI = 1.6-2.1, P = 0.001). In addition, maximum overshoot at 5 cm was greater than that at 7 cm (P = 0.020) and 8 cm (P = 0.037). The other LOR depths were not statistically significantly different from each other. Depth did not have a significant interaction with technique (P = 0.517). Technique preference had neither a significant relationship to maximum overshoot (P = 0.588) nor a significant interaction with LOR assessment technique (P = 0.689). DISCUSSION: Technique II LOR assessment produced the greatest needle overshoot past the simulated LOR plane after obtaining LOR. This was consistent across all LOR depths. In this bench study, the II technique resulted in the deepest needle tip maximum overshoot. We are in the process of designing a clinical study to collect similar data in patients.

Reduced Complications of Supraclavicular Approach in Simulated Central Venous Access: Applicability to Military Medicine.

In a study with 76 anesthesia providers on a mixed reality simulator, central venous access via the supraclavicular approach to the subclavian vein, without ultrasonography required less attempts compared to the infraclavicular approach. Participants had shorter times to venous access and larger improvements in confidence. Results from this simulation-based study indicate that the supraclavicular approach may deserve consideration as an alternative approach for central venous access in deployed military environments. The use of ultrasonography during the supraclavicular approach to the subclavian vein is also described which may improve its safety profile. This technique could be more appropriate in scenarios when central venous access is preferred over intraosseous access for patients being transported to another location for further care.

Serum markers and development of delayed neuropsychological sequelae after acute carbon monoxide poisoning: anion gap, lactate, osmolarity, S100B protein, and interleukin-6.

OBJECTIVE: Reliable biomarkers of delayed neuropsychological sequelae (DNS) after acute carbon monoxide (CO) poisoning are lacking. This study investigated the associations between potential serum markers and the development of DNS after acute CO poisoning. METHODS: Retrospective chart reviews were conducted for patients diagnosed with acute CO poisoning during a 28-month period. The patients were divided into two groups according to the presence or absence of having developed DNS. Multivariate analysis was performed to identify predictors of DNS after CO poisoning. RESULTS: Of a total of 102 patients, 10 (9.8%) developed DNS. The levels of serum osmolarity, S100B protein, and serum lactate, as well as serum anion gap, were statistically significant in univariate analysis. Multiple logistic regression analysis showed that anion gap (adjusted odds ratio [AOR], 1.36; 95% confidence interval [CI], 1.11 to 1.88), serum lactate level (AOR, 1.74; 95% CI, 1.26 to 2.75), and serum S100B protein level ([AOR, 7.02×105; 95% CI, 4.56×102 to 9.00×1010] in model 1, [AOR, 3.69×105; 95% CI, 2.49×102 to 2.71×1011] in model 2) were independently associated with DNS development. CONCLUSION: Based on our preliminary results, serum lactate level, serum anion gap, and serum S100B protein level in the emergency department could be informative predictors of DNS development in patients with acute CO poisoning. These markers might have the potential to improve early recognition of DNS in patients with acute CO poisoning.

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.

Pre-emptive ice cube cryotherapy for reducing pain from local anaesthetic injections for simple lacerations: a randomised controlled trial.

OBJECTIVE: Subcutaneous local anaesthetic injection can be painful to patients in the ED. We evaluated the effect of cryotherapy by application of an ice cube to the injection site prior to injection in patients with simple lacerations. METHODS: We conducted a prospective, randomised, controlled trial in consented patients with simple lacerations needing primary repair at a single emergency centre from April to July 2016. We randomly assigned patients undergoing repair for simple lacerations to either the cryotherapy group or the control group (standard care; no cryotherapy or other pretreatment of the injection site). In cryotherapy group subjects, we applied an ice cube (size: 1.5×1.5×1.5 cm) placed inside a sterile glove on the wound at the anticipated subcutaneous lidocaine injection site for 2 min prior to injection. The primary outcome was a subjective numeric rating (0-10 scale) of the perceived pain from the subcutaneous local anaesthetic injections. Secondary outcomes were (a) perceived pain on a numeric scale for cryotherapy itself, that is, pain from contact of the ice cube/glove with the skin and (b) the rate of complications after primary laceration repair. RESULTS: Fifty patients were enrolled, consented and randomised, with 25 in the cryotherapy group and 25 in the control group. The numeric rating scale for subcutaneous anaesthetic injections was median, IQR, 95% CI 2.0 (1 to 3.5), 1.81 to 3.47, respectively, in the cryotherapy group and 5.0 (3 to 7), 3.91 to 6.05 in the control group (Mann-Whitney U=147.50, p=0.001). No wound complications occurred in either group. The numeric rating scale for cryotherapy itself was median, IQR, 95% CI: 2.0 (1 to 3.5), 1.90 to 3.70. CONCLUSION: Pre-emptive topical injection site cryotherapy lasting 2 min before subcutaneous local anaesthetic injections can significantly reduce perceived pain from subcutaneous local anaesthetic injections in patients presenting for simple laceration repair. TRIAL REGISTRATION NUMBER: KCT0001990.

Higher Fresh Gas Flow Rates Decrease Tidal Volume During Pressure Control Ventilation.

BACKGROUND: We observed that increasing fresh gas flow (FGF) decreased exhaled tidal volume (VT) during pressure control ventilation (PCV). A literature search produced no such description whereby unintended VT changes occur with FGF changes during PCV. METHODS: To model an infant's lungs, 1 lung of a mechanical lung model (Dual Adult TTL 1600; Michigan Instruments, Inc, Grand Rapids, MI) was set at a compliance of 0.0068 L/cm H2O. An Rp50 resistor (27.2 cm H2O/L/s at 15 L/min) simulated normal bronchial resistance. The simulated lung was connected to a pediatric breathing circuit via a 3.5-mm cuffed endotracheal tube. A ventilator with PCV capability (Model 7900; Aestiva, GE Healthcare, Madison, WI) measured exhaled VT, and a flow monitor (NICO; Respironics, Murraysville, PA) measured peak inspiratory flow, positive end-expiratory pressure (PEEP), and peak inspiratory pressure. In PCV mode, exhaled VT displayed by the ventilator at FGF rates of 1, 6, 10, and 15 L/min was manually recorded across multiple ventilator settings. This protocol was repeated for the Avance CS2 anesthesia machine (GE Healthcare). RESULTS: For the Aestiva, higher FGF rates in PCV mode decreased exhaled VT. Exhaled VT for FGFs of 1, 6, 10, and 15 L/min were on average 48, 34.9, 16.5, and 10 mL, respectively, at ventilator settings of inspiratory pressure of 10 cm H2O, PEEP of 0 cm H2O, and respiratory rate of 20 breaths/min. This is a decrease by up to 27%, 65.6%, and 79.2% when FGFs of 6, 10, and 15 L/min are compared with a FGF of 1 L/min, respectively. In the GE Avance CS2 at the same ventilator settings, VT for FGF rates of 1, 6, 10, and 15 L/min were on average 46, 43, 40.4, and 39.7 mL, respectively. The FGF effect on VT was not as pronounced with the GE Avance CS2 as with the GE Aestiva. CONCLUSIONS: FGF has a significant effect on VT during PCV in the Aestiva bellows ventilator, suggesting caution when changing FGF during PCV in infants. Our hypothesis is that at higher FGF rates, an inadvertent PEEP is developed by the flow resistance of the ventilator relief valve that is not recognized by the ventilator. In turn, less change in pressure is needed to reach the set inspiratory pressure, resulting in lower VT delivery at higher FGF rates. This underappreciated FGF-VT interaction during PCV with a bellows ventilator may be clinically significant in pediatric patients; prospective data collection in patients is needed for further evaluation.