Injury Threshold Research Articles

Implementation of a new definition for acute kidney injury in the National Surgical Quality Improvement Project: What is the impact?

BackgroundThe National Surgical Quality Improvement Project is the preeminent surgical quality database, but it undercaptures acute kidney injury. Recently, the National Surgical Quality Improvement Project lowered the thresholds for acute kidney injury for the first time, so we assessed the impact of implementing the definition change on the rate of acute kidney injuries. MethodsFor this interrupted time series analysis, we assembled 2 institutional National Surgical Quality Improvement Project files to identify adults undergoing inpatient noncardiac nonvascular surgery. The acute kidney injury definition changed on July 1, 2021, so patients were stratified by their operative date into 12-month pre and post groups. Weighted covariate propensity score matching and logistic regression were used to balance the periods and compare outcomes. ResultsIn total, 4,784 adults were eligible (55% pre and 45% post change). The overall rate of postoperative outcomes was similar, aside for acute kidney injury (pre 0.3%, post 5.6%, P < .0001). Regardless of the period, patients with acute kidney injuries had significantly longer lengths of stay and morbidity and mortality rates compared to those without an acute kidney injury. After the definition change, 81% of acute kidney injuries were stage I, and none were identified by urine output alone. After matching, surgery after the definition change was associated with an increased weighted odds of an acute kidney injury compared to surgery before the change (odds ratio 26.2; 95% confidence interval, 12.1–56.8). ConclusionIn the year after the definition change, there was a 1,700% relative increase in the rate of reported acute kidney injuries. Newly identified acute kidney injuries are associated with high complication rates, and this definition change has implications for patient counseling, research, and quality reporting.

Psychological and psychosocial aspects of major trauma care: A survey of current practice across UK and Ireland

Introduction Psychological and psychosocial impacts of major trauma, defined as any injury that has the potential to be life-threatening and/or life changing, are common, far-reaching and often enduring. There is evidence that these aspects of major trauma care are often underserved. The aim of this research was to gain insight into the current provision and operationalisation of psychological and psychosocial aspects of major trauma care across the UK and Ireland. Methods A cross-sectional online survey, open to health professionals working in major trauma network hospitals was undertaken. The survey had 69 questions across six sections: Participant Demographics, Psychological First Aid, Psychosocial Assessment and Care, Assessing and Responding to Distress, Clinical Psychology Services, and Major Trauma Keyworker (Coordinator) Role. Results There were 102 respondents from across the regions and from a range of professional groups. Survey findings indicate a lack of formalised systems to assess, respond and evaluate psychological and psychosocial aspects of major trauma care, most notably for patients with lower-level distress and psychosocial support needs, and for trauma populations that don't reach threshold for serious injury or complex health need. The findings highlight the role of major trauma keyworkers (coordinators) in psychosocial aspects of care and that although major trauma clinical psychology services are increasingly embedded, many lack the capacity to meet demand. Conclusion Neglecting psychological and psychosocial aspects of major trauma care may extend peritraumatic distress, result in preventable Years Lived with Disability and widen post-trauma health inequalities. A stepped psychological and psychosocial care pathway for major trauma patients and their families from the point of injury and continuing as they move through services towards recovery is needed. Research to fulfil knowledge gaps to develop and implement such a model for major trauma populations should be prioritised along with the development of corresponding service specifications for providers.

Biomechanical Investigation of the Efficacy of Conventional Bicycle Helmets at Preventing Facial Injury

Many studies indicate that wearing a bicycle helmet significantly reduces the risk of accident-related head injuries. Less is reported, however, about bicycle helmet use, about preventing facial injury. Epidemiological studies typically report incidences of 'head injury,' though rarely categorize head, brain, and facial injuries separately. Studies that do focus on facial injury suggest that helmets do not provide adequate protection. A 3D biofidelic child head form and two conventional bicycle helmets (that is,” open face") were created in MSC ADAMS™ computer modelling and simulation software. Peak force and linear accelerations were measured for a series of head form impact simulations corresponding to an established testing standard and a newly proposed series of tests derived from modified motorcycle standards, incorporating injury thresholds from the facial bone impact tolerance literature. Almost all impact simulations exceeded the threshold for fracture, soft tissue, and dental trauma. An observational study was conducted using MSC ADAMS™ to assess a helmeted headform's face exposure during impact simulations. Helmets failed to reduce face impact exposure, during all simulations, except for perpendicular cheek impacts. International test standards, therefore, require urgent revision to ensure that face protection is included.

Relationship Between Musculoskeletal Load and Weight of Manual Fish Handling Via 2D Simulation

Fisherman experienced work-related musculoskeletal disorders (WMSDs) due to manual handling. Especially, manual handling for heavy fish makes physical load for fisherman. To prevent these WMSDs, fisherman should know the limit of weight in manual fish handling. Thus, the objective of this study was to find the relationship between the musculoskeletal load and weight of manual fish handling. This investigation was performed by the 2D musculoskeletal simulation. Posture of fishermen during manual fish handling on the commercial fishing boat was obtained from the Fishnet Open Images Database. Compression force of L5-S1 and joint torque of elbow, shoulder, knee, and ankle as musculoskeletal load were calculated by BlessPro2 software. The weight values of bigeye tuna, yellowfin tuna, and albacore tuna were used for this simulation. The results showed that compression force of L5-S1 and joint torque were increased with fish weight. In addition, the compression forces of L5-S1 during manual handling for bigeye tuna and yellowfin tuna were much larger than 3400 N as injury threshold of the National Institute of Occupational Safety and Health (NIOSH). These results indicate that fishermen should avoid heavy fish such as bigeye tuna and yellowfin tuna in manual fish handling for preventing WMSDs.

Short-term behavioral and histological changes in a rodent model of mild traumatic brain injury

An in-house developed weight drop injury (WDI) device is a recently described animal model of traumatic brain injury (TBI) that was designed to produce a blunt, closed-head injury. More specifically, the apparatus was designed to reliably generate a wide range of TBI severities using precise and quantifiable biomechanical inputs in a nonsurgical user-friendly platform. The objective of this study was to define the lower limit of a single mild TBI (mTBI) impact using our WDI device by characterizing the relationship between the biomechanical input and the behavioral and histological inflammatory outcomes. Rats were subjected to a single mTBI impact using two impact energies of 0.2 and 0.5J, and post-impact outcomes were assessed over two recovery periods of 3- and 7-days. Here we report that a single, closed-head impact energy of 0.5J and below produces no significant phenotype. Despite the insignificant results of alterations in behavior and inflammatory analysis, the study revealed important aspects of lower-level impact loads. First, this work provides evidence in support of the notion that not every closed-head impact has the capacity to result in system perturbations. Although a theoretical injury threshold may not exist for rats using a WDI model, we hypothesize a biomechanical threshold of impact associated with a lack of functional impairment and neuroinflammation due to a single closed-head injury is likely around an energy level of 0.5 J.

Development of detailed finite element models for in silico analyses of brain impact dynamics

Background and objectiveIn the last few decades, several studies have been performed to investigate traumatic brain injuries (TBIs) and to understand the biomechanical response of brain tissues, by using experimental and computational approaches. As part of computational approaches, human head finite element (FE) models show to be important tools in the analysis of TBIs, making it possible to estimate local mechanical effects on brain tissue for different accident scenarios. The present study aims to contribute to the computational approach by means of the development of three advanced FE head models for accurately describing the head tissue dynamics, the first step to predict TBIs. MethodsWe have developed three detailed FE models of human heads from magnetic resonance images of three volunteers: an adult female (32 yrs), an adult male (35 yrs), and a young male (16 yrs). These models have been validated against experimental data of post mortem human subjects (PMHS) tests available in the literature. Brain tissue displacements relative to the skull, hydrostatic intracranial pressure, and head acceleration have been used as the parameters to compare the model response with the experimental response for validation. The software CORAplus (CORrelation and Analysis) has been adopted to evaluate the bio-fidelity level of FE models. ResultsNumerical results from the three models agree with experimental data. FE models presented in this study show a good bio-fidelity for hydrostatic pressure (CORA score of 0.776) and a fair bio-fidelity brain tissue displacements relative to the skull (CORA score of 0.443 and 0.535). The comparison among numerical simulations carried out with the three models shows negligible differences in the mechanical state of brain tissue due to the different morphometry of the heads, when the same acceleration history is considered. ConclusionsThe three FE models, thanks to their accurate description of anatomical morphology and to their bio-fidelity, can be useful tools to investigate brain mechanics due to different impact scenarios. Therefore, they can be used for different purposes, such as the investigation of the correlation between head acceleration and tissue damage, or the effectiveness of helmet designs. This work does not address the issue to define injury thresholds for the proposed models.

The effect of seatback deformation on out-of-position front-seat occupants in severe rear impacts

Objective This study assesses the effects of seat deflection in severe oblique rear impacts with laterally out-of-position ATDs where the head is not supported by the head restraint. Method Six high-speed rear sled tests were conducted at 48 km/h with a 195 degree PDOF. A lap-shoulder belted 50th percentile Hybrid III ATD was leaned inboard and seated in six different front passenger seats (A-F); five of the seats were selected from mid-sized sedans and one was a non-production rigidified Seat Integrated Restraint (SIR) seat. FRED-III pull tests resulted in seat stiffnesses that varied from 73 to 172 N/mm. Seat F had the greatest stiffness. The seat and ATD responses were assessed. The biomechanical responses were evaluated and compared to relevant IARVs. Results In all tests the ATD moved rearward and twisted the seat. There was limited differential motion of the torso relative to the seatback. The ATD position and PDOF prevented head restraint engagement allowing head and neck extension over the seatback. The seatback angle was measured on the inboard side. At maximum yield, it was greatest with Seat E, followed by Seat A and Seat D, at 71, 67 and 62 degrees, respectively. The duration of rearward deformation was also greatest with Seat A, Seat D and Seat E providing longer ride-down. The head, chest and upper neck responses were below IARVs. Lower-neck extension moments were above injury threshold with Seat B, C and F. Seat F had the highest lower-neck moment. Conclusion Seats with greater deformation provided the greatest ride-down durations and the lowest overall biomechanical responses. The combination of high impact severity and lack of head support resulted in high lower-neck responses, highlighting the potential benefit of energy management from deforming seat structures.

Relationship Between the Completeness of Revascularization and Myocardial Injury in Patients Treated With Percutaneous Coronary Intervention

BackgroundClinical outcomes of patients suffering periprocedural myocardial injury and undergoing incomplete revascularization (IR) following percutaneous coronary intervention (PCI) has never been investigated. ObjectiveTo investigate the relationship between different thresholds of post-PCI cardiac troponin (cTn) elevation and revascularization completeness in determining long-term clinical outcomes. MethodsPatients were stratified in tertiles according to preprocedural SYNTAX score (SS) (low: 0–6; medium: >6–11; high: >11) and residual SS (low: 0–4; medium: >4–8; high: >8). IR was defined by a rSS value >4. Three thresholds of myocardial injury were pre-specified: 5×, 35× and 70× 99th percentile upper reference limit (URL) increase of baseline cTn. Primary outcome was a composite of major adverse cardiac events (MACE) at two years of follow-up. Results1061 patients undergoing PCI for stable coronary artery disease were enrolled. IR occurred in 249 (23.4 %) and major myocardial injury in 540 (50.9 %). Patients belonging to the highest tertile of SS showed an increased risk of experiencing IR and periprocedural myocardial injury. Two-year follow-up was available in 869. At multi-variate Cox's regression analysis, patients undergoing IR + cTn > 35 × URL and IR + cTn > 70 × URL showed an increased risk of MACE [HR 2.30 (1.19–4.41) and HR 3.20 (1.38–7.41); respectively]. ConclusionsPeriprocedural myocardial injury is critically associated with MACE at two-year follow-up in patient treated with PCI who achieve IR. Despite conflicting evidence exists regarding the influence of periprocedural myocardial injury on clinical outcomes, patients undergoing IR seem to represent a high-risk subgroup.

Characterization of Fluid Dynamics and Temperature Profiles During Ureteroscopy with Laser Activation in a Model Ureter.

Introduction: Ureteral thermal injury has been reported in patients following ureteroscopy with laser lithotripsy due to overheating of fluid within the ureter. Proper understanding of this risk necessitates knowing the volume of fluid available to absorb laser energy. This can be approximated as the volume of fluid that mixes during laser activation, since energy transfer through fluid is dominated by convection. Objectives of this study were to determine the volume of fluid that mixes during laser activation at different irrigation rates and to characterize the temporal/spatial temperature distribution in a model ureter. Methods: The model ureter consisted of a plastic tube-160 mm length and 5.3 mm inner diameter. Irrigation was first applied with clear, then dyed, deionized water at rates from 8 to 40 mL/min. The laser was activated at 20 W (0.5 J/40 Hz). The distances the dyed fluid propagated were measured and volumes calculated. Temperatures were recorded from six thermocouples-five embedded within the tube and one affixed to the ureteroscope. Thermal dose was calculated using the Dewey and Sapareto methodology. Results: The volume of total fluid mixing in the model ureter was ≤1.26 ± 0.10 cm3, consistent with a sharp temperature increase after laser activation from -5 to 25 mm from the ureteroscope tip. With irrigation rates ≤12 mL/min, calculated thermal dose within the model ureter exceeded the threshold of tissue injury and extended greater distances along the ureter with lower irrigation rates. Conclusion: The volume of total fluid mixing within the model ureter was found to be small thus conferring a greater risk of ureteral thermal injury. A thermocouple positioned near the tip of the ureteroscope reasonably approximates temperature in front of the ureteroscope. Until temperature sensors are incorporated into ureteroscopic systems, laser power settings should be carefully selected to minimize risk of ureteral thermal injury.

High sensitivity troponin I and newly/recently diagnosed coronavirus-19 disease patients presenting to the emergency department: values above and below the 99th percentile predict 28 day mortality

Abstract Background Studies indicate that the presence of cardiac injury [troponin level &amp;gt; the 99th percentile upper reference limit (99th % URL) using mostly contemporary assays] is predictive of death within 30 days during hospitalization of coronavirus disease 2019 (COVID-19) patients. Troponin measurements in these reports were ordered and/or resulted in the Emergency Department (ED) or during various times after hospital admission and not all patients were followed for 30 days. Purpose Our objective was to determine the 28 day survival prognostic value of Emergency Department (ED) resulted high sensitivity cardiac troponin I (hs-cTnI) measurements in all COVID-19 patients including those discharged after their ED visit or hospitalization. Methods An ED centric electronic database of COVID-19 patients (nasopharyngeal swab testing within 1 week prior to or during the ED visit) having at least 1 hs-cTnI (Beckman Coulter, Brea, CA; level of quantitation (LoQ) 4ng/L, non sex specific 99th % URL 18 ng/L) value reported during a visit to an urban, academic ED in the United States was constructed. All patients were followed for 28 days and Kaplan Meir survival curves constructed amongst predetermined initial hs-cTnI value intervals. Results From March 16-November 2, 2020 1476 consecutive ED COVID-19 patients were identified with 1044 (70.7%) having at least 1 hs-cTnI value resulted in the ED. Patients' mean age and body mass index were 60.8±16.1 years and 32.4±11.3 kg/m2 respectively. 531 (50.9%) were male, 804 (77.0%) self-identified as African American and 615 (58.9%) had 2 or more comorbidities with hypertension (42.5%), diabetes (37.4%) and hyperlipidemia (27.23%) commonest. Frequent primary presenting complaints were shortness of breath (37.7%), fever/chills (14.5%) and cough (11.9%). Hs-cTnI interval values were: 147 (14.1%) &amp;lt;4 (LoQ), 359 (34.4%) 4–10 and 151 (14.5%) 11–18 ng/L. Hs-cTnI values were &amp;gt;99th % URL in 387 (37.1%) patients with 230 (22.0%) 19–54, 63 (6.0%) 54–99 and 94 (9.0%) ≥100 (laboratory reported critical value) ng/L. 145 (13.9%) patients were discharged directly home and 2 (0.2%) died in the ED. 147 (14.1%) were admitted to an ICU with 104 (70.7%) dying. Each of the interval initial ED hs-cTnI values was associated with a different (p&amp;lt;0.001) 28 day survival curve. Conclusions Most COVID-19 patients had a hs-cTnI value obtained with 85.9% of these &amp;gt;4 ng/L. No one with an initial hs-cTnI &amp;lt;4 ng/L died within 28 days while increasing presenting hs-cTnI values &amp;gt;4 ng/L were associated with decreased 28 day survival. Our findings indicate that in COVID-19 patients detectable initial ED hs-cTnI values, whether reaching thresholds for cardiac injury or not, are highly prognostic of 28 day survival. Studies are needed to better define how hs-cTnI values could alter early management of COVID-19 disease to improve outcomes for these patients. Funding Acknowledgement Type of funding sources: Private hospital(s). Main funding source(s): Henry Ford Health System Department of Emergency Medicine

A noninvasive auditory prosthesis: Evaluation of a safety margin of the transtympanic laser stimulation

Cochlear implants are widely used for compensating the sensorineural hearing loss. Surgical intervention for implanting electrodes is one of the most significant obstacle for the further widespread of these devices. We proposed a non-invasive auditory prosthesis using infrared laser because the laser can stimulate cochlea nerves from the outer ear. The purpose of this study was to evaluate the safety margin of the transtympanic laser stimulation. Head-fixed classical conditioning was performed on Mongolian gerbils. Subjects were trained using auditory stimulus, a bandpass noise, as a conditioned stimulus for a water reward, and licking behavior was recorded as a conditioned response. After the training, each subject was exposed to continuous pulsed laser irradiation of 1.6, 3.3, 6.6, 26.4, 52.8, or 105.6 W/cm2 for 15 hours. The bandpass noise with various intensities was presented without the reward before and after one-day of the laser exposure. As a result, the licking rate did not change after laser exposure of 6.6 W/cm2 or weaker, but drastically decreased after 26.4 W/cm2or above. The result suggests that the injury threshold in Mongolian gerbils for transtympanic laser stimulation is between 6.6 and 26.4 W/cm2 and the exposure over 6.6 W/cm2 could be out of the safety margin.

Determining the threshold of acute renal parenchymal damage for intrarenal pressure during flexible ureteroscopy using an in vivo pig model.

To identify a threshold for intrarenal pressure (IRP), that if exceeded, will result in renal parenchymal damage. Herein, we attempt to identify an IRP threshold by subjecting in vivo porcine kidneys to various levels of extreme pressurized irrigation. Our objective was not to simulate ureteroscopy treatment, but to attempt identify a threshold of IRP injury. Ten female pigs were intubated and sedated. The abdomen was opened; the ureters were isolated and incised. A LithoVue™ (Boston Scientific) ureteroscope was inserted. A 0-silk tie was then used to tie the ureter around the scope to create a closed system (to achieve a constant level of pressure). Real-time IRPs were measured using the Comet™ Pressure guidewire (Boston Scientific). Kidneys were exposed to pressurized, saline for 36min (at control, 50, 100, 150mmHg and higher pressures). Kidneys were then immediately harvested. Two expert histologists independently analyzed kidney slides to identify areas of renal damage. The two kidneys exposed to IRPs > 185mmHg resulted in forniceal rupture and large areas of hematoma. The other IRP groups (control, 50, 100, and 150mmHg) had no identifiable gross or histologic renal parenchymal damage. No differences in renal parenchymal morphology were identified between pressure groups of control, 50, 100, or 150mmHg. However, IRPs > 185mmHg did result in forniceal rupture in this closed-system in vivo porcine model. Further study is required to elucidate the damage threshold.

Evaluation of muscle strain injury severity in active human body models

Even though significant efforts in the field of injury detection with finite element active human body models (FE AHBMs) have been made, injuries of the muscle-tendon unit (MTU) have not yet been taken into consideration. Therefore, the goal of this study was to define a muscle strain injury criterion (MSIC) to evaluate the damage sustained by the musculature during muscle driven movement scenarios. The MSIC was derived from biomechanical tests found in the literature and the proposed threshold values were substantiated through a comparison to an estimate of the ultimate tensile strength of human skeletal muscle and the forces acting on the biceps femoris long head muscle during one sprinting gait cycle. The application of the MSIC to state-of-the-art FE AHBMs was demonstrated by evaluating the strain injury severity of selected neck muscles of a full-body AHBM during two seat rotation load cases. The results of the MSIC substantiation suggest that all three injury threshold values proposed in this work fall in a plausible corridor of forces acting on the MTU. The combined results of the AHBM simulations indicate that neither of the two examined seat rotations are likely to cause strain injury to the neck muscles and that the proposed MSIC can easily be applied to current AHBMs without further modification of the model architecture or the muscle parameters. The MSIC was also used to formulate a hypothesis on the aetiology of muscle strain injuries, through which it was demonstrated that material inhomogeneities in the MTU might be the cause for strain injuries sustained during otherwise physiological movements. This work is a first step in the direction of the definition of a wholistic injury criterion for the human skeletal muscle fibre.

Thermography-Based Comparison of Irrigation Temperatures Between Moses Mode and Virtual Basket Mode: An In Vitro Phantom Study.

Objectives: This study aims to evaluate changes in irrigation fluid temperatures during laser activation by using thermography, with comparison between Moses mode (MM) and virtual basket mode (VBM). Materials and Methods: Experiments were performed using an unroofed pyelocaliceal model. The laser was fired for 60 seconds at 0.4 J/60 Hz. Three runs were tested per setting using short pulse mode, long pulse mode, MM contact, and VBM. The time to reach threshold of thermal injury (43°C) was evaluated using thermometer and thermography, both with and without saline irrigation (25 mL/min). These outcomes were compared between laser pulse modes. Results: In measurement of time to reach the threshold, thermography-based time was significantly shorter than thermometer-based time in all laser modes under the condition of no irrigation. Thermography measurement results indicate that the speed of temperature rise depends on laser pulse modes, and the time to reach the threshold in MM was significantly shorter than that in VBM (9.0 seconds vs 14.3 seconds, p = 0.03). When 25 mL/min saline irrigation was used, the peak temperatures by both thermometer and thermography measurements did not exceed the threshold during laser activation. Conclusions: Thermography-based evaluation suggests that irrigation temperatures near mucosa around stones can rapidly elevate during laser lithotripsy when the irrigation condition is poor. Temperature rise speed in MM may be more rapid than that in VBM. To prevent thermal injury, laser pulse modes must be used selectively according to the condition of irrigation.

Morphological changes in glial cells arrangement under mechanical loading: A quantitative study

The mechanical properties and microstructure of brain tissue, as its two main physical parameters, could be affected by mechanical stimuli. In previous studies, microstructural alterations due to mechanical loading have received less attention than the mechanical properties of the tissue. Therefore, the current study aimed to investigate the effect of ex-vivo mechanical forces on the micro-architecture of brain tissue including axons and glial cells. A three-step loading protocol (i.e., loading-recovery-loading) including eight strain levels from 5% to 40% was applied to bovine brain samples with axons aligned in one preferred direction (each sample experienced only one level of strain). After either the first or secondary loading step, the samples were fixed, cut in planes parallel and perpendicular to the loading direction, and stained for histology. The histological images were analyzed to measure the end-to-end length of axons and glial cell-cell distances. The results showed that after both loading steps, as the strain increased, the changes in the cell nuclei arrangement in the direction parallel to axons were more significant compared to the other two perpendicular directions. Based on this evidence, we hypothesized that the spatial pattern of glial cells is highly affected by the orientation of axonal fibers. Moreover, the results revealed that in both loading steps, the maximum cell-cell distance occurred at 15% strain, and this distance decreased for higher strains. Since 15% strain is close to the previously reported brain injury threshold, this evidence could suggest that at higher strains, the axons start to rupture, causing a reduction in the displacement of glial cells. Accordingly, it was concluded that more attention to glial cells’ architecture during mechanical loading may lead to introduce a new biomarker for brain injury.

Analysis of fall kinematics and injury risks in ground impact in car-pedestrian collisions using impulse

In vehicle-to-pedestrian collisions, pedestrian injuries occur due to contact with the car and the ground. Previous studies investigated pedestrian kinematic behavior using a parameter study or through statistical analysis although the force interaction between the pedestrian and the vehicle has not been considered.In this study, multibody analyses were conducted for vehicle–pedestrian collisions for adult and child pedestrian with various vehicle shapes. The impulse and impulse moment acting on the pedestrian from the vehicle were introduced, and the kinematic behavior, rotation and ground impact of the pedestrian model were examined. It was found that if an impulse moment acts on the pedestrian when the pedestrian re-contacts with the hood of the car, the angular velocity of the pedestrian’s torso changes in the opposite direction (away from the car), and the torso angle prior to the ground contact decreases to less than 90°. This re-contact between the pedestrian and the vehicle was more likely to occur for cases where the collision involves an adult pedestrian, lower hood leading edge (HLE), longer hood length, and lower collision velocity. When the pedestrian torso angle in contact with the ground was less than 90°, the head vertical impact velocity with respect to the ground became less than 2.9 m/s which corresponds to the injury threshold of the head.This study demonstrated that pedestrian-vehicle re-contact is crucial for reducing ground injury. The vehicle shape, pedestrian size, and collision velocity can determine whether re-contact of the pedestrian with the vehicle occurs. This can then explain the factors affecting pedestrian ground impact injury (e.g., higher HLE, higher risk of ground head injury for children) that were shown in previous studies. A strategy to mitigate ground injury is to apply enough impulse moment onto the pedestrian’s upper body from the hood in order to change the torso angular velocity during re-contact, thus making the torso angle less than 90°prior to the ground contact.

Combining advanced magnetic resonance imaging (MRI) with finite element (FE) analysis for characterising subject-specific injury patterns in the brain after traumatic brain injury

Traumatic brain injury (TBI) is a leading cause of death and disability. The way mechanical impact is transferred to the brain has been shown to be a major determinant for structural damage and subsequent pathological sequalae. Although finite element (FE) models have been used extensively in the investigation of various aspects of TBI and have been instrumental in characterising a TBI injury threshold and the pattern of diffuse axonal injuries, subject-specific analysis has been difficult to perform due to the complexity of brain structures and its material properties. We have developed an efficient computational pipeline that can generate subject-specific FE models of the brain made up of conforming hexahedral elements directly from advanced MRI scans. This pipeline was applied and validated in our sheep model of TBI. Our FE model of the sheep brain accurately predicted the damage pattern seen on post-impact MRI scans. Furthermore, our model also showed a complex time-varying strain distribution pattern, which was not present in the homogeneous model without subject-specific material descriptions. To our knowledge, this is the first fully subject-specific FE model of the sheep brain able to predict structural damage after a head impact. The pipeline developed has the potential to augment the analysis of human brain MRI scans to detect changes in brain structures and function after TBI.

Can emergency avoidance behavior reduce injuries to electric two-wheeler riders in vehicle collisions?

Objectives The aim of this study was to examine the effects of emergency avoidance behaviors on the kinematics and injuries of electric two-wheeler (ETW) riders. Methods Four typical riding postures of ETW riders before collisions, including one normal posture and three avoidance postures, were identified through analysis of 298 videos of vehicle to ETW accidents. Crash simulations were then performed using the Total Human Model of Safety (THUMS) occupant model, ETW and a sedan finite element (FE) model, and the kinematics of ETW riders were compared. The risk of head injury and lower extremity injury was also investigated. Results When the struck foot position of the ETW rider was lower than the ETW pedal, the lower extremity was struck by the sedan bumper and ETW frame from the right and left side respectively, and the upper body of the rider rotated around the hood leading edge. At a car velocity of 40 km/h, the rider was at high risk of head injury and the tibia was fractured. The medial cruciate ligament (MCL) was ruptured in both the 20 km/h and 40 km/h collisions. When the struck foot position of the ETW rider was higher than the pedal, the lower extremity was hit by the bumper and then rebounded. In this situation, the bending moments of the femur and tibia, as well as the bending angle and shear displacement of the knee joint were less than the injury threshold in all crash simulations. Furthermore, when the head was turned toward the colliding car, the risk of head injury varied with the emergency avoidance posture. Conclusions The height of the struck foot relative to the ETW pedal influenced the rider’s global kinematics, and head and lower extremity injuries risk. In the struck side foot landing and both feet landing postures, the lower extremity was restrained and compressed by the ETW frame, resulting in a high risk of tibia fracture and MCL rupture. Reducing the impact velocities could effectively mitigate the injury risk of the ETW riders; however, loading patterns remain an important factor influencing the risk of lower extremity injury.

The Impact of One Week of Pre-Stenting on Porcine Ureteral Luminal Circumference.

Objectives: Larger ureteral access sheaths (UASs) have the potential to improve ureteroscopic stone removal outcomes but are often avoided by surgeons because of concerns of ureteral injury. Using our novel UAS force sensor and previously defined force thresholds for ureteral injury, we sought to evaluate the impact of 1 week of stenting on the maximum safe dilation of ureteral luminal circumference. Methods: Twelve juvenile female Yorkshire pigs (24 ureters) were evaluated. The inner (i.e., luminal) circumference of each ureter was determined using Cook urethral dilators ranging from 8F to 24F in 2F increments, 37 cm in length. Each dilator was sequentially passed while applying the UAS force sensor to measure insertion force before and after 1 week of stent placement. Each ureter was randomized to receive either a 4.7F or 7.0F stent (20 cm). Maximum ureteral luminal circumference was defined as effective passage of the dilator to the ureteropelvic junction with ≤6 newtons (N) of force (the force threshold previously defined by porcine and clinical studies to avoid ureteral damage). After passage of the largest dilator at 6 N, flexible ureteroscopy was performed and a post-ureteroscopic lesion scale (PULS) was recorded. Results: After 1 week of stent placement, the median ureteral luminal circumference increased to 15F representing a mean increase of 3.8F ± 2.8F (p < 0.001). Twenty-one (88%) of the pre-stented ureters had an increase in luminal circumference, with 12 ureters (50%) dilated to ≥16F (p = 0.032), 6 ureters (25%) dilated to ≥18F, and in 2 cases a maximum size of 24F was recorded. The PULS grade was ≤2 in all cases, indicating no high-grade ureteral injuries. Laterality and stent size did not impact ureteral luminal circumference after pre-stenting (p = 0.232 and p = 0.337, respectively). Conclusions: One week of ureteral stenting resulted in nearly a 4F increase in the luminal circumference of porcine ureters.

PD19-04 NOBODY LIKES BURNT POPCORN: THE MOST EFFICIENT POPCORNING SETTINGS IN A NOVEL 3D-KIDNEY MODEL THAT LIMITS THERMAL INJURY

You have accessJournal of UrologyCME1 May 2022PD19-04 NOBODY LIKES BURNT POPCORN: THE MOST EFFICIENT POPCORNING SETTINGS IN A NOVEL 3D-KIDNEY MODEL THAT LIMITS THERMAL INJURY Christian Tabib, Zachary Dionise, Sabrina Tran, Francois Soto-Palou, Pei Zhong, Glenn Preminger, and Michael Lipkin Christian TabibChristian Tabib More articles by this author , Zachary DioniseZachary Dionise More articles by this author , Sabrina TranSabrina Tran More articles by this author , Francois Soto-PalouFrancois Soto-Palou More articles by this author , Pei ZhongPei Zhong More articles by this author , Glenn PremingerGlenn Preminger More articles by this author , and Michael LipkinMichael Lipkin More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000002557.04AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: When stone popcorning, the use of higher energy with little to no irrigation is preferred. However, this combination of high power with low flow can lead to increased risk of thermal damage with longer laser firing times. Using predetermined lasering and irrigation ‘cool down’ durations within a novel, anatomically accurate 3D kidney model, our aim was to identify the laser settings that produce the most efficient popcorning without reaching thermal dose (t43) that causes tissue damage. METHODS: Hard Begostone phantoms, mimicking calcium oxalate monohydrate stones, were crushed and sieved to 2-4mm fragments. Fragments were then separated by size measuring 2-2.8mm, 2.8-3.35mm, and 3.35-4mm and mixed by mass at a ratio of 2:2:1, respectively. Approximately 0.5g of fragments were placed in the upper pole of our anatomical 3D-printed kidney model. Each triplicate trial consisted of iterative laser/irrigation cooling cycles for two minutes using a MosesTM 120H 2.0 laser (Table). Laser firing and cooling times were determined by measuring t43 with each laser setting, allowing for maximal laser to cooling ratio that would not exceed tissue injury threshold (t43 70 min). After treatment, stones were dried and sieved into <1mm, 1-2mm, 2-2.8mm, 2.8-3.35, and 3.35-4mm fragments, which were then weighed. Ablation efficiency was calculated as post-treatment mass <1mm, with comparisons by ANOVA and Tukey post-hoc tests. RESULTS: Overall, the most efficient setting was 0.5J/90Hz with no irrigation; while the most efficient setting using low irrigation were 0.4J/110Hz and 0.5/J/80Hz SP (Figure). Even with shorter laser times, popcorning was more efficient with no irrigation, especially at high powers (all p<0.05). CONCLUSIONS: When accounting for thermal dose, 0.5J/90Hz without irrigation provides the most efficient popcorning, despite shorter laser times. When thermal injury is of special concern and the surgeon prefers low flow, 0.4J/110Hz appears most efficient. Last, if extended frequency is unavailable, 0.6J/80Hz without irrigation should be used. Source of Funding: None © 2022 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 207Issue Supplement 5May 2022Page: e350 Advertisement Copyright & Permissions© 2022 by American Urological Association Education and Research, Inc.MetricsAuthor Information Christian Tabib More articles by this author Zachary Dionise More articles by this author Sabrina Tran More articles by this author Francois Soto-Palou More articles by this author Pei Zhong More articles by this author Glenn Preminger More articles by this author Michael Lipkin More articles by this author Expand All Advertisement PDF DownloadLoading ...