David E. Lizdas

Mixed Reality Ventriculostomy Simulation: Experience in Neurosurgical Residency

BACKGROUND: Medicine and surgery are turning toward simulation to improve on limited patient interaction during residency training. Many simulators today use virtual reality with augmented haptic feedback with little to no physical elements. In a collaborative effort, the University of Florida Department of Neurosurgery and the Center for Safety, Simulation & Advanced Learning Technologies created a novel “mixed” physical and virtual simulator to mimic the ventriculostomy procedure. The simulator contains all the physical components encountered for the procedure with superimposed 3-D virtual elements for the neuroanatomical structures. OBJECTIVE: To introduce the ventriculostomy simulator and its validation as a necessary training tool in neurosurgical residency. METHODS: We tested the simulator in more than 260 residents. An algorithm combining time and accuracy was used to grade performance. Voluntary postperformance surveys were used to evaluate the experience. RESULTS: Results demonstrate that more experienced residents have statistically significant better scores and completed the procedure in less time than inexperienced residents. Survey results revealed that most residents agreed that practice on the simulator would help with future ventriculostomies. CONCLUSION: This mixed reality simulator provides a real-life experience, and will be an instrumental tool in training the next generation of neurosurgeons. We have now implemented a standard where incoming residents must prove efficiency and skill on the simulator before their first interaction with a patient. ABBREVIATIONS: AANS, American Association of Neurological Surgeons EVD, external ventricular drain PGY, postgraduate year SNS, Society Neurological Surgeons

Understanding of anesthesia machine function is enhanced with a transparent reality simulation.

Introduction: Photorealistic simulations may provide efficient transfer of certain skills to the real system, but by being opaque may fail to encourage deeper learning of the structure and function of the system. Schematic simulations that are more abstract, with less visual fidelity but make system structure and function transparent, may enhance deeper learning and optimize retention and transfer of learning. We compared learning effectiveness of these 2 modes of externalizing the output of a common simulation engine (the Virtual Anesthesia Machine, VAM) that models machine function and dynamics and responds in real time to user interventions such as changes in gas flow or ventilation. Methods: Undergraduate students (n = 39) and medical students (n = 35) were given a single, 1-hour guided learning session with either a Transparent or an Opaque version of the VAM simulation. The following day, the learners’ knowledge of machine components, function, and dynamics was tested. Results: The Transparent-VAM groups scored higher than the Opaque-VAM groups on a set of multiple-choice questions concerning conceptual knowledge about anesthesia machines (P = 0.009), provided better and more complete explanations of component function (P = 0.003), and were more accurate in remembering and inferring cause-and-effect dynamics of the machine and relations among components (P = 0.003). Although the medical students outperformed undergraduates on all measures, a similar pattern of benefits for the Transparent VAM was observed for these 2 groups. Conclusions: Schematic simulations that transparently allow learners to visualize, and explore, underlying system dynamics and relations among components may provide a more effective mental model for certain systems. This may lead to a deeper understanding of how the system works, and therefore, we believe, how to detect and respond to potentially adverse situations.

Mixed-reality simulation for neurosurgical procedures.

BACKGROUND: Surgical education is moving rapidly to the use of simulation for technical training of residents and maintenance or upgrading of surgical skills in clinical practice. To optimize the learning exercise, it is essential that both visual and haptic cues are presented to best present a real-world experience. Many systems attempt to achieve this goal through a total virtual interface. OBJECTIVE: To demonstrate that the most critical aspect in optimizing a simulation experience is to provide the visual and haptic cues, allowing the training to fully mimic the real-world environment. METHODS: Our approach has been to create a mixed-reality system consisting of a physical and a virtual component. A physical model of the head or spine is created with a 3-dimensional printer using deidentified patient data. The model is linked to a virtual radiographic system or an image guidance platform. A variety of surgical challenges can be presented in which the trainee must use the same anatomic and radiographic references required during actual surgical procedures. RESULTS: Using the aforementioned techniques, we have created simulators for ventriculostomy, percutaneous stereotactic lesion procedure for trigeminal neuralgia, and spinal instrumentation. The design and implementation of these platforms are presented. CONCLUSION: The system has provided the residents an opportunity to understand and appreciate the complex 3-dimensional anatomy of the 3 neurosurgical procedures simulated. The systems have also provided an opportunity to break procedures down into critical segments, allowing the user to concentrate on specific areas of deficiency.BACKGROUND Surgical education is moving rapidly to the use of simulation for technical training of residents and maintenance or upgrading of surgical skills in clinical practice. To optimize the learning exercise, it is essential that both visual and haptic cues are presented to best present a real-world experience. Many systems attempt to achieve this goal through a total virtual interface. OBJECTIVE To demonstrate that the most critical aspect in optimizing a simulation experience is to provide the visual and haptic cues, allowing the training to fully mimic the real-world environment. METHODS Our approach has been to create a mixed-reality system consisting of a physical and a virtual component. A physical model of the head or spine is created with a 3-dimensional printer using deidentified patient data. The model is linked to a virtual radiographic system or an image guidance platform. A variety of surgical challenges can be presented in which the trainee must use the same anatomic and radiographic references required during actual surgical procedures. RESULTS Using the aforementioned techniques, we have created simulators for ventriculostomy, percutaneous stereotactic lesion procedure for trigeminal neuralgia, and spinal instrumentation. The design and implementation of these platforms are presented. CONCLUSION The system has provided the residents an opportunity to understand and appreciate the complex 3-dimensional anatomy of the 3 neurosurgical procedures simulated. The systems have also provided an opportunity to break procedures down into critical segments, allowing the user to concentrate on specific areas of deficiency.

An audible indication of exhalation increases delivered tidal volume during bag valve mask ventilation of a patient simulator.

Self-inflating manual resuscitators (SIMRs) can mislead caregivers because the bag, unlike a Mapleson-type device, reinflates even without patient exhalation. We added a whistle as an audible indicator to the exhalation port of a SIMR. In randomized order, each participant provided two sets of breaths via mask ventilation with a SIMR, one with and one without audible feedback, to a Human Patient Simulator modified to log lung volume changes. The last three breaths in each set were used to compare average tidal volume (Vt) under both conditions. Eighty-seven advanced cardiac life support trainees (54 males, 33 females) with clinical experience averaging 6.4 ± 9.4 yr were recruited. Average Vt delivered with the standard SIMR was 486 ± 166 mL and 624 ± 96 mL with the modified SIMR. Average Vt delivered by a modified SIMR was significantly larger by 40% when it followed standard SIMR use and 19% when using the modified SIMR first. Use of a SIMR with an audible indicator of exhalation significantly (P < 0.001) increased mask ventilation of a patient simulator, suggesting that mask ventilation of a patient with a SIMR may also be increased by objective, real-time feedback of exhaled Vt.

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.

Interactive Web Simulation for Propofol and Fospropofol, a New Propofol Prodrug

Using pharmacokinetic and pharmacodynamic data published in the scientific literature, we have developed interactive on-line simulations to model administration of propofol and fospropofol, a new water-soluble prodrug formulation of propofol. The prodrug formulation of fospropofol leads to a delayed onset to peak concentrations of propofol. A comparison simulation that overlays administration of fospropofol and propofol allows clinicians to understand the differences of administering fospropofol and traditional propofol. The simulations have the added advantage of allowing for differences among patients documented in test studies and the use of different models.

Using a Critical Incident Scenario With Virtual Humans to Assess Educational Needs of Nurses in a Postanesthesia Care Unit

Introduction: During critical incidents, teamwork failures can compromise patient safety. This study provides evidence that virtual humans can be used in simulated critical incidents to assess the learning needs of health professionals, and provide important information that can inform the development of continuing education programs in patient safety. We explored the effectiveness of information transfer during a devolving medical situation between postanesthesia care unit (PACU) nurses and a virtual attending physician. Methods: We designed a three‐stage scenario: tutorial, patient transfer, and critical incident. We developed 2 checklists to assess information transfer: Critical Patient Information and Interprofessional Communication Skills. All participants were videotaped; 2 raters reviewed all videos and assessed performance using the checklists. Results: Participants (n = 43) who completed all 3 stages scored 62.3% correct on critical patient information transfer and 61.6% correct on interprofessional communication skills. Almost 87% missed a fatal drug error. The checklists measured each item on a 1/0 (done/not) calculation. Additionally, no relationship was found between years of nursing experience and performance on either checklist. Discussion: The PACU nurses in this study did not consistently share critical information with an attending (virtual) physician during a critical incident, and most missed a fatal dosage error. These findings strongly suggest a crucial need for additional structured team training among practicing health care teams, and they demonstrate the utility of using virtual humans to simulate team members.

Prevalence of dependent loops in urinary drainage systems in hospitalized patients.

PURPOSE: The purpose of this study was to measure the prevalence and configuration of dependent loops in urinary drainage systems in hospitalized, catheterized adults. SUBJECTS: The study sample comprised 141 patients with indwelling urinary catheters; subjects were hospitalized at an academic health center in northern Florida. METHODS: We measured the prevalence of dependent loops in urine drainage systems and the incidence of urine-filled dependent loops over a 3-week period. We measured the heights of the crest (Hc), trough (Ht), and, when urine-filled dependent loops were present, the patient-side (Hp) and bag-side (Hb) menisci with a laser measurement system. All variables were measured in centimeters. RESULTS: The majority of observed urine drainage systems (85%) contained dependent loops in the drainage tubing and 93.8% of the dependent loops contained urine. Hc and Ht averaged 45.1 ± 11.1 and 27 ± 16.7 cm, respectively. Meniscus height difference (Hb − Hp) averaged 8.2 ± 5.8 and −12.2 ± 9.9 cm when Hp < Hb (65.3%) and Hp > Hb (32.7%), respectively. CONCLUSIONS: We found that dependent loops are extremely common in urinary drainage systems among hospitalized patients despite the manufacturer recommendations and nursing and hospital policies. Maintaining the urine drainage tubing free of dependent loops would require incorporation into nursing care priorities and workflow as inadvertent force on the tubing, for example, patient movement or nurse contact can change tubing configuration and allow excess drainage tubing to re-form a dependent loop.

Automated, real-time fresh gas flow recommendations alter isoflurane consumption during the maintenance phase of anesthesia in a simulator-based study.

BACKGROUND: The Low Flow Wizard (LFW) provides real-time guidance for user optimization of fresh gas flow (FGF) settings during general inhaled anesthesia. The LFW can continuously inform users whether it determines their FGF to be too little, efficient, or too much, and its color-coded recommendations respond in real time to changes in FGF performed by users. Our study objective was to determine whether the LFW feature, as implemented in the Dräger Apollo workstation, alters FGF selection and thereby volatile anesthetic consumption without affecting patient care. METHODS: To reduce potentially confounding variables, we used a human patient simulator that consumes and exhales volatile anesthetics. Standard monitoring was provided for the patient initially with invasive arterial blood pressure added after anesthetic induction. In this within-group study, each of 17 participants acted as his or her own control. Each participant was asked to anesthetize an identical simulated patient twice using a Dräger Apollo workstation, first with the LFW feature disabled and subsequently enabled. The volatile anesthetic was isoflurane. Both simulation runs were set up to have similar time durations for the different phases of anesthesia: induction, incision, and maintenance. Emergence was not simulated. The isoflurane vaporizer was weighed before and after each simulation run on a digital scale to verify total computed volatile liquid anesthetic consumption. In addition, the product of FGF (reported by the Apollo) times the isoflurane volumetric concentration (sampled by a multigas analyzer at the equivalent of the FGF hose for the Apollo) was integrated over time to obtain isoflurane consumption rate (on-the-fly anesthetic consumption rate measurement). RESULTS: The maintenance isoflurane consumption rate and FGF were significantly lower with the LFW display enabled than without (P = 0.005). The mean reduction in FGF was 53.6% (95% confidence interval, 39.2%–67.9%). There was no significant difference in alveolar isoflurane concentration (P = 0.13 for differences <0.1%). The isoflurane consumption measurement closely matched the consumption measured via the digital scale. CONCLUSIONS: Our data in a simulated anesthetic suggest that enabling the display of FGF efficiency data by the LFW results in a median percent reduction in volatile liquid anesthetic consumption rate of 53.2%. Since the lower limit of the 95% confidence interval for the median is 39.4%, this finding is likely to translate into cost savings and less waste anesthetic gas generated in the clinical setting and released into the atmosphere.

Virtual humans for inter-ethnic variability training in sedation and analgesia.

The objective of this research is to enable realistic Virtual Humans (VH) that support inter-ethnic variability training. Inter-ethnic variability refers to differences in response to medical treatment, such as drug administration, due to ethnicity (e.g., Caucasian, African American, or South Asian). Most current approaches to VHs do not model these differences. Our approach consists of driving VH responses based on a real time pharmacodynamic / pharmacokinetic propofol model that includes inter-ethnic variability. Results of a user study with 22 medical students suggest that utilizing VHs for inter-ethnic variability training is feasible and can increase awareness of inter-ethnic variability.