Prolonged, High-Fidelity Simulation for Study of Patient Care in Resource-Limited Medical Contexts and for Technology Comparative Effectiveness Testing.

Most high-fidelity medical simulation is of limited duration, used for education and training, and rarely intended to study medical technology. U.S. caregivers working in prehospital, resource-limited settings may need to manage patients for extended periods (hours to days). This "prolonged casualty care" occurs during military, wilderness, humanitarian, disaster, and space medicine. We sought to develop a standardized simulation model that accurately reflects prolonged casualty care in order to study caregiver decision-making and performance, training requirements, and technology use in prolonged casualty care. DESIGN: Model development. SETTING: High-fidelity simulation laboratory. SUBJECTS: None. INTERVENTIONS: We interviewed subject matter experts to identify relevant prolonged casualty care medical challenges and selected two casualty types to further develop our model: a large thermal burn model and a severe hypoxia model. We met with a multidisciplinary group of experts in prolonged casualty care, nursing, and critical care to describe how these problems could evolve over time and how to contextualize the problems with a background story and clinical environment with expected resource availability. Following initial scenario drafting, we tested the models with expert clinicians. After multiple tests, we selected the hypoxia model for refinement and testing with inexperienced providers. We tested and refined this model until two research teams could proctor the scenario consistently despite subject performance variability. MEASUREMENTS AND MAIN RESULTS: We developed a 6-8-hour simulation model that represented a 14-hour scenario. This model of pneumonia evolved from presentation to severe hypoxia necessitating advanced interventions including airway, breathing, and shock management. The model included: context description, caregiver orientation scripts, hourly progressive physiology tracks corresponding to caregiver interventions, intervention/procedure-specific physiology tracks, intervention checklists, equipment lists, prestudy checklists, photographs of setups, procedure, telementor, and role player scripts, business rules, and data collection methods. CONCLUSIONS: This is the first standardized, high-fidelity simulation model of prolonged casualty care described in the literature. It may be used to assess caregiver performance and patient outcomes resulting from that performance during a complex, 14-hour prolonged casualty care scenario. Because it is standardized, the model may be used to compare differences in the impact of new technologies upon caregiver performance and simulated patient outcomes..

Mitigating Ischemia-Reperfusion Injury Using a Bilobed Partial REBOA Catheter: Controlled Lower-Body Hypotension.

BACKGROUND: Non-compressible torso hemorrhage (NCTH) is the leading cause of potentially preventable death on the battlefield. Resuscitative endovascular balloon occlusion of the aorta (REBOA) aims to restore central blood pressure and control NCTH below the balloon, but risks ischemia-reperfusion injury to distal organs when prolonged. We tested a bilobed partial REBOA catheter (pREBOA), which permits some of the blood to flow past the balloon. METHODS: Female swine (n = 37, 6 groups, n = 5-8/group), anesthetized and instrumented, were exponentially hemorrhaged 50% of estimated blood volume (all except time controls [TC]). Negative controls (NC) did not receive REBOA or resuscitation. Positive controls (PC) received retransfusion after 120 min. REBOA groups received REBOA for 120 min, then retransfusion. Balloon was fully inflated in the full REBOA group (FR), and was partially inflated in partial REBOA groups (P45 and P60) to achieve a distal systolic blood pressure of 45 mm Hg or 60 mm Hg. RESULTS: Aortic occlusion restored baseline values of proximal mean arterial pressure, cardiac output, and carotid flow in pREBOA groups. Lactate reached high values during occlusion in all REBOA groups (9.9 ±â€Š4.2, 8.0 ±â€Š4.1, and 10.7 ±â€Š2.9 for P45, P60, and FR), but normalized by 6 to 12 h post-deflation in the partial groups. All TC and P60 animals survived 24 h. The NC, PC, and P45 groups survived 18.2 ±â€Š9.5, 19.3 ±â€Š10.6, and 21.0 ±â€Š8.4 h. For FR animals mean survival was 6.2 ±â€Š5.8 h, significantly worse than all other animals (P < 0.01, logrank test). CONCLUSIONS: In this porcine model of hemorrhagic shock, animals undergoing partial REBOA for 120 min survived longer than those undergoing full occlusion.

Automatic proximal airway volume segmentation using optical coherence tomography for assessment of inhalation injury.

BACKGROUND: Acute respiratory distress syndrome (ARDS) is a severe form of acute lung injury with a mortality rate of up to 40%. Early management of ARDS has been difficult due to the lack of sensitive imaging tools and robust analysis software. We previously designed an optical coherence tomography (OCT) system to evaluate mucosa thickness (MT) after smoke inhalation, but the analysis relied on manual segmentation. The aim of this study is to assess in vivo proximal airway volume (PAV) after inhalation injury using automated OCT segmentation and correlate the PAV to lung function for rapid indication of ARDS. METHODS: Anesthetized female Yorkshire pigs (n = 14) received smoke inhalation injury (SII) and 40% total body surface area thermal burns. Measurements of PaO2-to-FiO2 ratio (PFR), peak inspiratory pressure (PIP), dynamic compliance, airway resistance, and OCT bronchoscopy were performed at baseline, postinjury, 24 hours, 48 hours, 72 hours after injury. A tissue segmentation algorithm based on graph theory was used to reconstruct a three-dimensional (3D) model of lower respiratory tract and estimate PAV. Proximal airway volume was correlated with PFR, PIP, compliance, resistance, and MT measurement using a linear regression model. RESULTS: Proximal airway volume decreased after the SII: the group mean of proximal airway volume at baseline, postinjury, 24 hours, 48 hours, 72 hours were 20.86 cm (±1.39 cm), 17.61 cm (±0.99 cm), 14.83 cm (±1.20 cm), 14.88 cm (±1.21 cm), and 13.11 cm (±1.59 cm), respectively. The decrease in the PAV was more prominent in the animals that developed ARDS after 24 hours after the injury. PAV was significantly correlated with PIP (r = 0.48, p < 0.001), compliance (r = 0.55, p < 0.001), resistance (r = 0.35, p < 0.01), MT (r = 0.60, p < 0.001), and PFR (r = 0.34, p < 0.01). CONCLUSION: Optical coherence tomography is a useful tool to quantify changes in MT and PAV after SII and burns, which can be used as predictors of developing ARDS at an early stage. LEVEL OF EVIDENCE: Prognostic, level III.

Early Complement and Fibrinolytic Activation in a Rat Model of Blast-Induced Multi-Organ Damage.

OBJECTIVE: Blast injury is associated with multi-organ failure (MOF), causing significant morbidity and mortality in trauma patients. However, the pathogenesis of blast-induced MOF still remains obscure. In this study, we evaluate the pathophysiological changes related to blast-induced MOF in a clinically relevant rat model of blast injury. METHODS: A moderate blast overpressure was applied to induce injury in anesthetized rats. Pathological changes were evaluated by H&E staining. Complement activation, plasminogen, and myeloperoxidase levels were analyzed by complement hemolytic assay (CH50) and/or ELISA in blood samples. RESULTS: Analysis of lung, brain, and liver tissue at 24 hour after blast overpressure revealed severe injuries. The level of complement components C3 and C1q decreased in parallel with the reduction of CH50 level in injured animals at 1, 3, and 6 hours after blast. Consumption of plasminogen was also detected as early as 1 hour post-injury. Myeloperoxidase levels were elevated within 1 hour of blast injury. CONCLUSION: Our data reveal that blast injury triggers the complement and fibrinolytic systems, which likely contribute to blast-induced MOF. Conceivably, therapies that target these systems early may improve clinical outcomes in blast patients.

Point-of-care endoscopic optical coherence tomography detects changes in mucosal thickness in ARDS due to smoke inhalation and burns.

BACKGROUND: The prevalence of acute respiratory distress syndrome (ARDS) in mechanically ventilated burn patients is 33%, with mortality varying from 11-46% depending on ARDS severity. Despite the new Berlin definition for ARDS, prompt bedside diagnosis is lacking. We developed and tested a bedside technique of fiberoptic-bronchoscopy-based optical coherence tomography (OCT) measurement of airway mucosal thickness (MT) for diagnosis of ARDS following smoke inhalation injury (SII) and burns. METHODS: 16 female Yorkshire pigs received SII and 40% thermal burns. OCT MT and PaO2-to-FiO2 ratio (PFR) measurements were taken at baseline, after injury, and at 24, 48, and 72h after injury. RESULTS: Injury led to thickening of MT which was sustained in animals that developed ARDS. Significant correlations were found between MT, PFR, peak inspiratory pressure (PIP), and total infused fluid volume. CONCLUSIONS: OCT is a useful tool to quantify MT changes in the airway following SII and burns. OCT may be effective as a diagnostic tool in the early stages of SII-induced ARDS and should be tested in humans.

Assessment of clients health needs of two urban Native American health centers in the San Francisco Bay Area.

A needs assessment was compiled from self-administered questionnaires completed by 796 clients at the Urban Indian Health Service clinics in San Francisco and Oakland, California. Data on the health disparities between Native Americans and Alaskan Natives and the rest of the U.S. population are limited. The data that exist, however, indicate that Native Americans continue to fare worse than the general population. This needs assessment reveals the same trend among a sample of clients of two Native American Health Centers in the San Francisco Bay Area and provides further information about the health needs and interests of the population currently attending these centers.