Computer Simulation to Assess Emergency Department Length of Stay in Pediatric Traumatic Brain Injury.

OBJECTIVES: Our study aimed to identify how emergency department (ED) arrival rate, process of care, and physical layout can impact ED length of stay (LOS) in pediatric traumatic brain injury care. METHODS: Process flows and value stream maps were developed for 3 level I pediatric trauma centers. Computer simulation models were also used to examine "what if" scenarios based on ED arrival rates. RESULTS: Differences were observed in prearrival preparation time, ED physical layouts, and time spent on processes. Shorter prearrival preparation time, trauma bed location far from diagnostic or treatment areas, and ED arrival rates that exceed 20 patients/day prolonged ED LOS. This was particularly apparent in 1 center where computer simulation showed that relocation of trauma beds can reduce ED LOS regardless of the number of patients that arrive per day. CONCLUSIONS: Exceeding certain threshold ED arrival rates of children with traumatic brain injury can substantially increase pediatric trauma center ED LOS but modifications to ED processes and bed location may mitigate this increase.

Driving characteristics of young adults prior to and following concussion.

OBJECTIVES: This study sought to examine whether young adults who sustain concussions have different driving histories and pre-injury driving styles than uninjured peers. In addition, we assessed whether modifications were made to driving behavior in the acute period following concussion. METHODS: Self-reported driving and demographic information was collected from 102 16- to 25-year-old drivers. Half of the sample had recently sustained concussions and the other half comprised a matched comparison group. RESULTS: The groups reported similar pre-injury driving behaviors and styles. However, the recently injured group had more driving citations, higher rates of psychiatric disorders, and greater likelihood of having sustained a prior concussion. Self-reported driving habits postconcussion suggested that most drivers did not modify their driving behavior following concussion, though they were less likely to drive at night or with others in the car. CONCLUSION: Results highlight the need for postconcussion driving guidelines and support for returning to driving safely.

Cognitive Impairment and Driving Skills in Youth After Concussion.

Abstract Concussions can impact cognitive processes necessary for driving. Young adults, a group who are more likely to engage in risky behaviors, have limited driving experience and a higher rate of motor vehicle collisions; they may be at higher risk for driving impairment after concussion. There are no clear guidelines for return-to-driving following a concussion. We sought to examine the simulated driving performance of young drivers after receiving medical care following a concussion, compared with a similar control population, to examine the association of driving performance with performance on neuropsychological tests. We evaluated 47 drivers, 16- to 25-year-old, within 3 weeks of sustaining a concussion and 50 drivers with similar characteristics who had not sustained concussions. Participants completed demographic questionnaires, the Sport Concussion Assessment Tool-5 (SCAT-5), and a brief set of neurocognitive tests, including the National Institutes of Health (NIH) Toolbox Cognition Battery and the Trail Making Test, and a simulated driving assessment. At various times during simulated driving, participants were asked to respond to tactile stimuli using the tactile detection response task (TDRT), a validated method of testing cognitive load during simulated driving. The concussion group reported significantly higher symptoms on the SCAT-5 than the comparison group. Performance on crystallized neurocognitive skills was similar between groups. Performance on fluid neurocognitive skills was significantly lower in the concussion than comparison group, although scores were in the normal range for both groups. Simulated driving was similar between groups, although there was a small but significant difference in variation in speed as well as TDRT miss rate, with worse performance by the concussion group. Symptom report on the SCAT-5 was significantly associated with TDRT miss rate. In addition, neurocognitive test scores significantly predicted TDRT reaction time and miss count with medium to large effect sizes. Results suggest that neurocognitive screening may be a useful tool for predicting capacity to return to drive. However, further research is needed to determine guidelines for how neuropsychological tests can be used to make return to driving recommendations and to evaluate effects of concussion on real world driving.

Provider perceptions of severe pediatric traumatic brain injury care priorities across hospitals in South America before and during the COVID-19 pandemic.

BACKGROUND: To understand provider perceptions of the COVID-19 pandemic on priorities of severe pediatric traumatic brain injury (TBI) care across hospitals in South America. METHODS: Site principal investigators (PIs) from 17 hospitals in South America enrolled in the PEGASUS-Argentina randomized controlled trial completed questionnaires regarding order of tasks performed in the care of a typical pediatric patient with severe TBI before (2019) and during (2021) the COVID-19 pandemic. Acute care processes were examined by quintiles to identify early, mid, and late actions and were categorized and compared. Associations of hospital volume and subspecialty resource availability with prioritization of key process actions were examined. FINDING: Site PIs from 15 and 16 hospitals completed the surveys in 2019 and 2021, respectively, including 14 who completed both. Action category order was stable between 2019 and 2021 and were ranked in priorities as: initial encounter, primary survey, interventions and invasive monitors, diagnostics, medications, staff communication, then disposition (in 2019) or nutrition (in 2021). There was variation in specific action order between hospitals at both timepoints, with only a few initial encounter and disposition actions limited to a single quintile. There was no reported association between hospital volume or subspecialty resource availability with prioritization of key process actions. INTERPRETATION: Despite novel healthcare challenges presented by the COVID-19 pandemic, providers in South America perceived maintaining standard severe pediatric TBI care consistent with BTF guidelines. There was large variability in specific action order between individual hospitals reported.

Driving behavior at midblock crosswalks with Rectangular Rapid Flashing Beacons: Hidden Markov model approach using naturalistic data.

Pedestrian fatalities have increased in the U.S. with the largest increase being observed on urban arterials and away from intersections. Rectangular Rapid Flashing Beacon (RRFB) has been widely implemented as a safety countermeasure to improve driver awareness and visibility of pedestrians, especially for midblock crosswalks. Studies show that drivers are more likely to yield to pedestrians at crosswalks with an RRFB. These studies are often based on a binary outcome of whether or not drivers yield to pedestrians. Nevertheless, it is also important to consider the drivers' deceleration behavior as a dynamic process at these crosswalks and the impact of pedestrians being present or not. Understanding this dynamic behavior and the related circumstances can provide information on the design of alerting systems that help drivers make more appropriate decisions at these crosswalks to avoid a vehicle-pedestrian crash. This study examined this research topic using Hidden Markov Models (HMMs) and data from a naturalistic study. More specifically, four HMMs were applied to the naturalistic brake and jerk data from the Safety Pilot Model Deployment (SPMD) program given drivers' intention to slow down, the RRFB activation status, and the presence of pedestrians. The time-based data sequence was converted to distance-based through a moving window to enhance result comparison and interpretation. Grid-search was used to select the best moving window parameters and the optimal number of hidden states. This study confirmed the high compliance at an activated RRFB when pedestrians were present. Even without pedestrians, one in five traversals showed drivers slowing down to less than 8.94 m/s (20 mph) within 35 m of the crosswalk. Model results further indicate that drivers started braking as far back as 180 m before the crosswalk and stopped braking from 70 m before the crosswalk at an activated RRFB without pedestrians. When there were pedestrians, drivers would start braking 20 to 30 m later but would brake more firmly and for longer. Finally, drivers were not likely to brake or decelerate when RRFB was off and no pedestrians were present.

Sparse group regularization for semi-continuous transportation data.

Motor vehicle crashes are a global public health concern. Most analysis have used zero-inflated count models for examining crash counts. However, few methods are available to account for safety metrics that have semi-continuous observations. This article considers the problem of variable selection for the semi-continuous zero-inflated (SCZI) models. These models include two parts: a zero-inflated part and a nonzero continuous part. A special group regularization is designed to accommodate the unique structure of two-part SCZI models, and a type of Bayesian information criterion is proposed to select tuning parameters. We illustrate the variable selection process of the proposed model using lane position data from a driving simulator study. In the study, drivers stay in the intended lane for the majority of their drive (zero-inflated part). On occasion, some drivers do drift out of their intended driving lane (nonzero continuous part). Our findings show that individual differences can be captured with the proposed model, which has implications for driving safety and the design of in-vehicle alerting systems.

Auditory Messages for Intersection Movement Assist (IMA) Systems: Effects of Speech- and Nonspeech-Based Cues.

OBJECTIVE: The objective of this study was to assess the effects of different warning messages for an Intersection Movement Assist (IMA) based on drivers' ability to avoid a potential safety hazard. BACKGROUND: An IMA system can detect hazards and warn drivers when it is unsafe to enter an intersection. The effects of different warning information conveyed by these systems are still unknown. METHOD: A driving simulator study with 80 participants was conducted with a red light running (RLR) scenario using a 5 (warnings) x 2 (training) between-subject design. IMA warnings included the messages "Danger," "Brake now," "Vehicle on your left," a beep, and no IMA warning. Training was provided to half of the participants. Analysis of variance and logistic regression models were used to examine differences in drivers' avoidance behavior. RESULTS: The analyses showed that all tested warning messages can significantly enhance drivers' avoidance performance. Significant differences were observed in crash occurrence, avoidance behavior (i.e., reaction time and speed change), and eye movements (i.e., fixation pattern and time to first fixation). The effects of training also differed given the warning message provided. CONCLUSION: The "Brake now" message performed best in reducing crash involvement and prompted better avoidance performance. The "Danger" and "Vehicle on your left" messages improved drivers' hazard detection ability. The training showed a potential to enhance the effectiveness of nonspeech warning messages. APPLICATION: The findings of this study can help designers and engineers better design IMA warning messages for RLR scenarios.

Comparisons of physical exposure between workers harvesting apples on mobile orchard platforms and ladders, part 1: Back and upper arm postures.

This study compared farmworkers' exposure to non-neutral postures using a new mobile platform apple harvesting method and the traditional method using ladders. Twenty-four workers were recruited and assigned into three groups: ladder workers (n = 8) picking apples from full trees using a ladder, mobile platform workers (n = 8) picking apples from upper part of the trees while standing on a moving platform, and ground-based mobile platform workers (n = 8) picking apples from lower part of the trees which the mobile platform workers left out. Upper arm and back inclinations were continuously monitored during harvesting using tri-axial accelerometers over full work shifts (~8 h). Upper arm posture was characterized as the percentage of time that upper arm flexion and abduction exceeded 30°, 60°, and 90°. Back posture was characterized as the percentage of time that torso angles (sagittal flexion or lateral bending) exceeded 10°, 20°, and 30°. The 10th, 50th, and 90th postural percentiles were also calculated. The platform workers had lower exposures to upper arm flexion and abduction than the ground and ladder workers. There were no differences in torso angles between the ladder and mobile platform workers; however, the ground workers were exposed to more and greater percentages of time in torso flexions.

Comparisons of physical exposure between workers harvesting apples on mobile orchard platforms and ladders, part 2: Repetitive upper arm motions.

Farmworkers are exposed to physical risk factors including repetitive motions. Existing ergonomic assessment methods are primarily laboratory-based and, thus, inappropriate for use in the field. This study presents an approach to characterize the repetitive motions of the upper arms based on direct measurement using accelerometers. Repetition rates were derived from upper arm inclination data and with video recordings in the field. This method was used to investigate whether harvesting with mobile platforms (teams harvesting apples from the platform and the ground) increased the farmworkers' exposure to upper arm repetitive motions compared to traditional harvesting using ladders. The ladder workers had higher repetitive motions (13.7 cycles per minute) compared to the platform and ground workers (11.7 and 12.2 cycles per minutes). The higher repetitions in the ladder workers were likely due to their ability to work independently and the additional arm movements associated with ladder climbing and walking.

Human factors considerations in designing a personalized mobile dialysis device: An interview study.

Recent technical advances have enabled the creation of mobile dialysis device prototypes. These prototypes have been tested for their ability to allow an individual to be dialyzed continuously rather than sporadically. The most recent prototype of a mobile dialysis device aims at increased functionality, which suggests that human factors issues (e.g., efficiency, bulkiness, and weight) are now considered carefully. This study describes advances in the design of an Ambulatory Kidney to Improve Vitality (AKTIV), using an interview protocol during the early stages of product development to capture patients' and caregivers' reactions. The AKTIV has the potential to improve patients' quality of life and decrease mortality rates. The goal of our study is to examine patients' and caregivers' design preferences and feature considerations for an AKTIV. We interviewed 22 participants (age M = 57.50, SD = 13.30), of whom 12 were female and 16 were patients. A pre-interview survey was distributed to the participants, and semi-structured interviews were subsequently held. The pre-interview results show that the belt and backpack designs were preferred over the shoulder bag and distributed designs. The participants also indicated on their pre-interview forms that safety and accuracy were more important to them than attachment ease, comfort, compactness, or operational simplicity. Invisibility and mobility were frequently mentioned when determining the strengths of each of the five design types during the interviews. Finally, individual differences in preferences for the various design types and attributes were identified. The results from our study have important implications for improving efficiency, effectiveness, and user satisfaction in relation to AKTIV prototypes and products. The findings from this interview study will help to ensure engineers and clinicians have target parameters for redesigning the AKTIV.

Allocation of Driver Attention for Varying In-Vehicle System Modalities.

OBJECTIVE: This paper examines drivers' allocation of attention using response time to a tactile detection response task (TDRT) while interacting with an in-vehicle information system (IVIS) over time. BACKGROUND: Longer TDRT response time is associated with higher cognitive workload. However, it is not clear what role is assumed by the human and system in response to varying in-vehicle environments over time. METHOD: A driving simulator study with 24 participants was conducted with a restaurant selection task of two difficulty levels (easy and hard) presented in three modalities (audio only, visual only, hybrid). A linear mixed-effects model was applied to identify factors that affect TDRT response time. A nonparametric time-series model was also used to explore the visual attention allocation under the hybrid mode over time. RESULTS: The visual-only mode significantly increased participants' response time compared with the audio-only mode. Females took longer to respond to the TDRT when engaged with an IVIS. The study showed that participants tend to use the visual component more toward the end of the easy tasks, whereas the visual mode was used more at the beginning of the harder tasks. CONCLUSION: The visual-only mode of the IVIS increased drivers' cognitive workload when compared with the auditory-only mode. Drivers showed different visual attention allocation during the easy and hard restaurant selection tasks in the hybrid mode. APPLICATION: The findings can help guide the design of automotive user interfaces and help manage cognitive workload.

Intersections and Non-Intersections: A Protocol for Identifying Pedestrian Crash Risk Locations in GIS.

Intersection and non-intersection locations are commonly used as spatial units of analysis for modeling pedestrian crashes. While both location types have been previously studied, comparing results is difficult given the different data and methods used to identify crash-risk locations. In this study, a systematic and replicable protocol was developed in GIS (Geographic Information System) to create a consistent spatial unit of analysis for use in pedestrian crash modelling. Four publicly accessible datasets were used to identify unique intersection and non-intersection locations: Roadway intersection points, roadway lanes, legal speed limits, and pedestrian crash records. Two algorithms were developed and tested using five search radii (ranging from 20 to 100 m) to assess the protocol reliability. The algorithms, which were designed to identify crash-risk locations at intersection and non-intersection areas detected 87.2% of the pedestrian crash locations (r: 20 m). Agreement rates between algorithm results and the crash data were 94.1% for intersection and 98.0% for non-intersection locations, respectively. The buffer size of 20 m generally showed the highest performance in the analyses. The present protocol offered an efficient and reliable method to create spatial analysis units for pedestrian crash modeling. It provided researchers a cost-effective method to identify unique intersection and non-intersection locations. Additional search radii should be tested in future studies to refine the capture of crash-risk locations.

Identifying characteristics that impact motor carrier safety using Bayesian networks.

PROBLEM STATEMENT: In the U.S., a safety rating is assigned to each motor carrier based on data obtained from the Motor Carrier Management Information System (MCMIS) and an on-site investigation. While researchers have identified variables associated with the safety ratings, the specific direction of the relationships are not necessarily clear. OBJECTIVE: The objective of this study is to identify those relationships involved in the safety ratings of interstate motor carriers, the largest users of the U.S. transportation network. METHOD: Bayesian networks are used to learn these relationships from data obtained from MCMIS for a 6-year period (2007-2012). RESULTS: Our study shows that safety rating assignment is a complex process with only a subset of the variables having statistically significant relationship with safety rating. They include driver out-of-service violations, weight violations, traffic violations, fleet size, total employed drivers, and passenger & general carrier indicators. APPLICATION: The findings have both immediate implications and long term benefits. The immediate implications relate to better identification of unsafe motor carriers, and the long term benefits pertain to policies and crash countermeasures that can enhance carrier safety.

Behavioral Adaptations to Lane Keeping Systems: Effects of Exposure and Withdrawal.

OBJECTIVE: A driving simulator study was conducted to evaluate the longitudinal effects of an intervention and withdrawal of a lane keeping system on driving performance and cognitive workload. BACKGROUND: Autonomous vehicle systems are being implemented into the vehicle fleet. However, limited research exists in understanding the carryover effects of long-term exposure. METHODS: Forty-eight participants (30 treatment, 18 control) completed eight drives across three separate days in a driving simulator. The treatment group had an intervention and withdrawal of a lane keeping system. Changes in driving performance (standard deviation of lateral position [SDLP] and mean time to collision [TTC]) and cognitive workload (response time and miss rate to a detection response task) were modeled using mixed effects linear and negative binomial regression. RESULTS: Drivers exposed to the lane keeping system had an increase in SDLP after the system was withdrawn relative to their baseline. Drivers with lane keeping had decreased mean TTC during and after system withdrawal compared with manual drivers. There was an increase in cognitive workload when the lane keeping system was withdrawn relative to when the system was engaged. CONCLUSION: Behavioral adaptations in driving performance and cognitive workload were present during automation and persisted after the automation was withdrawn. APPLICATION: The findings of this research emphasize the importance to consider the effects of skill atrophy and misplaced trust due to semi-autonomous vehicle systems. Designers and policymakers can utilize this for system alerts and training.

Evaluating variability in foot to pedal movements using functional principal components analysis.

There are reasons why the driver's foot may not be applied to the correct pedal while driving and this can lead to unintended consequences. In this study, we seek to capture common and unique patterns of variations in drivers' foot movements using functional principal components analysis (FPCA). This analysis technique was used to analyze three categories of pedal response types (direct hits, corrected trajectories, and pedal errors) based on the various foot to pedal trajectories. Data from a driving simulator study with video data of foot movements for 45 drivers was used for analyses. Most foot movements show common patterns associated with direct hits and corrected trajectories with some level of variation. However, those foot movements associated with unique patterns might be early indicators of pedal errors. The findings of this study can be used with collision mitigation systems to provide early detection of foot trajectories that are more likely to result in a pedal error.

Timely Hemodynamic Resuscitation and Outcomes in Severe Pediatric Traumatic Brain Injury: Preliminary Findings.

OBJECTIVES: Early resuscitation may improve outcomes in pediatric traumatic brain injury (TBI). We examined the association between timely treatment of hypotension and hypoxia during early care (prehospital or emergency department locations) and discharge outcomes in children with severe TBI. METHODS: Hypotension was defined as systolic blood pressure less than 70 + 2 (age in years), and hypoxia was defined as PaO2 less than 60 mm Hg or oxygen saturation less than 90% in accordance with the 2003 Brain Trauma Foundation guidelines. Timely treatment of hypotension and hypoxia during early care was defined as the treatment within 30 minutes of a documented respective episode. Two hundred thirty-six medical records of children younger than 18 years with severe TBI from 5 regional pediatric trauma centers were examined. Main outcomes were in-hospital mortality and discharge Glasgow Outcome Scale (GOS) score. RESULTS: Hypotension occurred in 26% (60/234) during early care and was associated with in-hospital mortality (23.3% vs 8.6%; P = 0.01). Timely treatment of hypotension during early care occurred in 92% (55/60) by use of intravenous fluids, blood products, or vasopressors and was associated with reduced in-hospital mortality [adjusted relative risk (aRR), 0.46; 95% confidence interval, 0.24-0.90] and less likelihood of poor discharge GOS (aRR, 0.54; 95% confidence interval, 0.39-0.76) when compared to children with hypotension who were not treated in a timely manner. Early hypoxia occurred in 17% (41/236) and all patients received timely oxygen treatment. CONCLUSIONS: Timely resuscitation during early care was common and associated with lower in-hospital mortality and favorable discharge GOS in severe pediatric TBI.

Simulation of the Emergency Department Care Process for Pediatric Traumatic Brain Injury.

The treatment of patients in the emergency department (ED) with severe pediatric traumatic brain injury (TBI) is challenging, and treatment process strategies that facilitate good outcomes are not well documented. The overall objective of this study was to identify factors that can affect the care process associated with pediatric TBI. This objective was achieved using a discrete-event simulation model of patients with TBI as they progress through the ED treatment process of a Level I trauma center. This model was used to identify areas where the ED length of stay can be reduced. The number of patients arriving at any given time was also varied in the simulation model to observe the impact to bed allocation policies and changes in staff and equipment. The findings showed that implementing changes in the ED (i.e., availability of two computerized tomography scanners, formation of resuscitation teams that included eight staff personnel, and modifying the bed allocation policy) could result in a 17% reduction in the mean ED length of stay. The study outcomes would be of interest to those (e.g., health administrators, health managers, and physicians) who can make decisions related to the treatment process in an ED.

Frequency of and factors associated with emergency department intracranial pressure monitor placement in severe paediatric traumatic brain injury.

OBJECTIVE: To examine the frequency of and factors associated with emergency department (ED) intracranial pressure (ICP) monitor placement in severe paediatric traumatic brain injury (TBI). METHODS: Retrospective, multicentre cohort study of children <18 years admitted to the ED with severe TBI and intubated for >48 hours from 2007 to 2011. RESULTS: Two hundred and twenty-four children had severe TBI and 75% underwent either ED, operating room (OR) or paediatric intensive care unit (PICU) ICP monitor placement. Four out of five centres placed ICP monitors in the ED, mostly (83%) fibreoptic. Nearly 40% of the patients who received ICP monitors get it placed in the ED (29% overall). Factors associated with ED ICP monitor placement were as follows: age 13 to <18 year olds compared to infants (aRR 2.02; 95% CI 1.37, 2.98), longer ED length of stay (LOS) (aRR 1.15; 95% CI 1.08, 1.21), trauma centre designation paediatric only I/II compared to adult/paediatric I/II (aRR 1.71; 95% CI 1.48, 1.98) and higher mean paediatric TBI patient volume (aRR 1.88;95% CI 1.68, 2.11). Adjusted for centre, higher bedside ED staff was associated with longer ED LOS (aRR 2.10; 95% CI 1.06, 4.14). CONCLUSION: ICP monitors are frequently placed in the ED at paediatric trauma centres caring for children with severe TBI. Both patient and organizational level factors are associated with ED ICP monitor placement.

Examining Emergency Department Treatment Processes in Severe Pediatric Traumatic Brain Injury.

BACKGROUND: In the treatment of pediatric traumatic brain injury (TBI), timely treatment of patients can affect the outcome. Our objectives were to examine the treatment process of acute pediatric TBI and the impact of non-value-added time (NVAT) on patient outcomes. METHODS: Data for 136 pediatric trauma patients (age < 18 years) with severe TBI from 2 trauma centers in the United States were collected. A process flow and value stream map identified NVATs and their sources in the treatment process. Cluster and regression analysis were used to examine the relationship between NVAT, as a percentage of the patient's length of stay (LOS), and the patient outcome, measured by their corresponding Glasgow outcome scale. RESULTS: There were 14 distinct sources of NVAT identified. A regression analysis showed that increased NVAT was associated with less favorable outcomes (relative ratio = 1.015, confidence interval = [1.002-1.029]). Specifically, 1% increase in the NVAT-to-LOS ratio was associated with a 1.5% increase in the chance of a less favorable outcome (i.e., death or vegetative state). CONCLUSION: The NVAT has a significant impact on the outcome of pediatric TBI, and every minute spent on performing non-value-added processes can lead to an increase in the likelihood of less favorable outcomes.

Foot placement during error and pedal applications in naturalistic driving.

Data from a naturalistic driving study was used to examine foot placement during routine foot pedal movements and possible pedal misapplications. The study included four weeks of observations from 30 drivers, where pedal responses were recorded and categorized. The foot movements associated with pedal misapplications and errors were the focus of the analyses. A random forest algorithm was used to predict the pedal application types based the video observations, foot placements, drivers' characteristics, drivers' cognitive function levels and anthropometric measurements. A repeated multinomial logit model was then used to estimate the likelihood of the foot placement given various driver characteristics and driving scenarios. The findings showed that prior foot location, the drivers' seat position, and the drive sequence were all associated with incorrect foot placement during an event. The study showed that there is a potential to develop a driver assistance system that can reduce the likelihood of a pedal error.