Changing the management of refractory ventricular fibrillation: The consideration of earlier utilization of dual sequential defibrillation.

Dual Sequential Defibrillation (DSD) has shown promise in the management of refractory ventricular fibrillation (RVF). In the recent past, there have been a number of reports on the topic with varying results. Some studies have concluded that DSD provides no benefit over standard defibrillation therapy of RVF in terms of survival and neurological outcome. In fact, termination of RVF and achieving return of spontaneous circulation (ROSC) are achieved quite frequently in patients with DSD. Unfortunately, DSD has been utilized very late in the course of resuscitation, likely masking a great deal of its potential benefit. Interventions at this later phase of resuscitation are much less likely to produce a beneficial outcome, regardless of their ability to impact the course of events. It is suggested that earlier use of DSD can potentially improve ROSC, ultimate survival, and neurological outcome. After a review of the existing literature on the topic, we will propose that DSD be considered for use at a much earlier time in the resuscitation of patients with RVF. In addition to the consideration of its use in resuscitation, clinicians and device manufacturers must also address the impact on the two defibrillation devices employed in DSD due to the potential for damage and resultant defibrillator dysfunction.

Nonurgent commercial air travel after acute coronary syndrome: a review of 288 patient events.

OBJECTIVES: We studied a population of individuals who experienced an acute coronary syndrome (ACS) event while traveling abroad and required nonurgent commercial air travel to the home region. METHODS: This retrospective study gathered data from 288 patients enrolled in a travel-based medical assistance program. Interventions, complications, and travel home were assessed for trends. Descriptive and comparison statistical analyses were performed. RESULTS: Two hundred eighty-eight patients were identified and entered into the review. Of the patients in this study, 77.1% were male with an average age of 67.7 years. One hundred sixteen (40.3%) patients were diagnosed with unstable angina pectoris (USAP), whereas the remaining 172 (59.7%) patients experienced acute myocardial infarction (AMI). Regarding inpatient complications during the initial admission, 121 (42.0%) patients experienced 1 or more adverse event. The average number of days after an ACS event that a patient began to travel home was 10.5 days for the entire patient population (USAP patients = 8.8 days, AMI patients = 11.8 days). Two hundred twenty (76.4%) patients traveled with a medical escort, and 48 (16.7%) patients received supplemental oxygen during air travel. Four (1.4%) in-flight adverse events occurred in the following ACS diagnostic groups: 2 in the complicated AMI group, 1 in the uncomplicated USAP group, and 1 in the uncomplicated AMI group. No in-flight deaths occurred. Nine (3.1%) deaths were noted within 2 weeks after returning to the home region. The deaths after returning to the home region occurred in the following ACS diagnostic groups: 2 in the complicated USAP group, 1 in the uncomplicated USAP group, and 6 in the complicated AMI group. None of the patients who experienced in-flight events died after returning to their home region. CONCLUSIONS: Upon discharge, the vast majority of ACS patients who travel to their home region via commercial air do not experience adverse events in-flight; when such adverse events occur in-flight, these events do not result in a poor outcome. No in-flight deaths occurred; death occurred in a minority of patients after returning to their home region, particularly in the complicated USAP and AMI groups, who were planned readmissions to the hospital.

Back to basics: Practical strategies to reduce sensory overstimulation in the emergency department identified by adults and caregivers of children with autism spectrum disorder.

INTRODUCTION: Sensory overstimulation of autistic patients of all ages during an ED visit can ultimately lead to care escalation, but few studies have evaluated patient perspectives on improving the ED sensory experience across the age continuum. The purpose of this study was to explore patient-centered perspectives on reducing adult and pediatric autistic patients' sensory stimulation during an ED visit. METHODS: We used a qualitative descriptive design to explore how autistic patients experience sensory disruption and recommendations to improve care. Data were analyzed inductively using an overall categorization of 6 senses (visual, auditory, touch, smell, taste, and proprioception). RESULTS: Fourteen adults and 30 caregivers of children provided written responses to open-ended interview questions (n = 44). Participants suggested strategies to minimize the sensory disruption they experienced; however, an overarching recommendation was for clinicians to ask about their or their child's preferences before delivering care or services. CONCLUSION: Because people with autism are more likely to visit an ED than their neurotypical counterparts, ED clinicians should be proficient in "sensory-friendly care." A variety of evidence-based practical strategies and design approaches exist that can be leveraged to reduce the risk of care escalation; however, the most basic may be to prioritize asking patients and their caregivers about their preferences prior to providing care.

GLass intact Assures Safe cervical Spine protocol.

BACKGROUND: Selective cervical spine immobilization performed by Emergency Medical Services (EMS) is being utilized with increasing frequency. These protocols, although very sensitive, still include subjective data such as "mild cervical discomfort." The aim of this study is to create an objective clinical decision rule that would enhance the selective approach for cervical spine immobilization in patients aged 16-60 years. STUDY OBJECTIVE: It is hypothesized that, in a motor vehicle crash, the integrity of the involved vehicle's glass window and airbag status is an excellent objective measure for the amount of energy a vehicle occupant has experienced during the crash. GLass intact Assures Safe Spine (GLASS) is an easy and objective method for evaluation of the need for prehospital cervical spine immobilization. METHODS: A retrospective cohort study was performed with sample motor vehicle crash cases to evaluate the performance of the GLASS rule. The National Accident Sampling System-Crashworthiness Data System (NASS-CDS) was utilized to investigate tow-away motor vehicle crashes, including their glass damage characteristics and occupant injury outcomes, over an 11-year period (1998-2008). Sample occupant cases selected for this study were patients aged 16-60 years, who were belt-restrained front seat occupants involved in a crash with no airbag deployment, and no glass damage before the crash. RESULTS: A total of 14,191 occupants involved in motor vehicle crashes were evaluated in this analysis. The results showed that the sensitivity of the GLASS rule was 95.20% (95% confidence interval [CI] 91.45-98.95%), the specificity was 54.27% (95% CI 53.44-55.09%), and the negative predictive value was 99.92% (95% CI 99.86-99.98%). CONCLUSION: The GLASS rule presents the possibility of a novel, more objective tool for cervical spine clearance. Prospective evaluation is required to further evaluate the validity of this clinical decision rule.

Spinal injury rates and specific causation in motor vehicle collisions.

Motor vehicle collisions (MVCs) are a leading cause of acute spinal injuries. Chronic spinal pathologies are common in the population. Thus, determining the incidence of different types of spinal injuries due to MVCs and understanding biomechanical mechanism of these injuries is important for distinguishing acute injuries from chronic degenerative disease. This paper describes methods for determining causation of spinal pathologies from MVCs based on rates of injury and analysis of the biomechanics require to produce these injuries. Rates of spinal injuries in MVCs were determined using two distinct methodologies and interpreted using a focused review of salient biomechanical literature. One methodology used incidence data from the Nationwide Emergency Department Sample and exposure data from the Crash Report Sample System supplemented with a telephone survey to estimate total national exposure to MVC. The other used incidence and exposure data from the Crash Investigation Sampling System. Linking the clinical and biomechanical findings yielded several conclusions. First, spinal injuries caused by an MVC are relatively rare (511 injured occupants per 10,000 exposed to an MVC), which is consistent with the biomechanical forces required to generate injury. Second, spinal injury rates increase as impact severity increases, and fractures are more common in higher-severity exposures. Third, the rate of sprain/strain in the cervical spine is greater than in the lumbar spine. Fourth, spinal disc injuries are extremely rare in MVCs (0.01 occupants per 10,000 exposed) and typically occur with concomitant trauma, which is consistent with the biomechanical findings 1) that disc herniations are fatigue injuries caused by cyclic loading, 2) the disc is almost never the first structure to be injured in impact loading unless it is highly flexed and compressed, and 3) that most crashes involve predominantly tensile loading in the spine, which does not cause isolated disc herniations. These biomechanical findings illustrate that determining causation when an MVC occupant presents with disc pathology must be based on the specifics of that presentation and the crash circumstances and, more broadly, that any causation determination must be informed by competent biomechanical analysis.

Breadth of use of The Abbreviated Injury Scale in The National Trauma Data Bank bank.

OBJECTIVE: The Abbreviated Injury Scale (AIS) is an anatomic-based injury coding system that strives to provide sufficient detail to differentiate unique injuries for the purposes of research and quality assurance, while limiting the total number of codes to facilitate efficient use. It has been shown that a substantial portion of codes are unused in automotive-trauma specific databases. The goal of this study was to determine the percentage of codes utilized in a nationwide trauma registry that includes multiple mechanisms of injury. Secondary objectives were to examine unused codes and determine the number of codes that were most frequently utilized. METHODS: Data were obtained from the National Trauma Data Bank (NTDB) years 2016 and 2017. All injury data were recorded using AIS version 2005 update 2008 (AIS08), which contains 1,999 distinct injury codes. The percentage of the total number of AIS08 codes used in NTDB were determined for each year individually and the combination of both years. The unused codes were then examined manually to identify common characteristics. Finally, the number of codes that provided 95% coverage of all recorded injuries was calculated. RESULTS: There were 6,661,110 injuries recorded for 1,953,775 patients in NTDB over the two-year period. A small percentage of codes had an incorrect severity level (0.07%) or an incorrect injury code (0.0002%). There were 1,987 (99.4% of the entire AIS dictionary) unique AIS08 codes utilized in each year, with the unused codes varying between years. The unused codes tended to involve specific nerves, dural sinuses, or severe, bilateral injuries. During the combined two-year period, 1,996 (99.8% of the entire dictionary) unique AIS08 codes were used. Although almost every code was used at least once, 95% of the injuries in NTDB used only the 631 (31.6%) most frequent AIS08 codes. CONCLUSIONS: In contrast to automotive specific databases, nearly all the AIS08 codes are used each year in the NTDB. Over a two-year period, only three AIS08 injuries were unused. However, less than a third of AIS08 codes encompass 95% of the injuries. Further research is necessary to determine if common codes should be separated into multiple distinct codes to enhance discriminatory ability of AIS.

Large-event medicine--event characteristics impacting medical need.

Large events have been defined in many ways, from the vague description of a focused gathering of people to the more specific description of an event with at least 1,000 spectators and participants who are gathered at a specific location for a defined period of time. Regardless of the definition applied, the actual medical requirements vary considerably from one event to the next. The ability to predict these medical needs allows for the provision of adequate medical support. Many factors contribute to medical need at a large event, including event type, weather (particularly heat index), the presence of alcohol and / or illicit drugs, the number of participants, event duration, crowd demographics, and venue characteristics. This review will focus on the various features of large events such that the medical planner can better understand the challenge and provide adequate resource for patient care.

National survey of emergency department alcohol screening and intervention practices.

STUDY OBJECTIVE: We describe current alcohol screening and brief intervention practices in emergency departments (EDs) at Level I and Level II trauma centers and characterize ED directors' attitudes and perceived barriers associated with these practices among injured patients in the ED. METHODS: ED directors at Level I and Level II trauma centers were surveyed about current alcohol screening and intervention practices in the ED, as well as knowledge, attitudes, and perceived barriers to these practices. RESULTS: Nearly half (46.0%) of ED directors surveyed responded. The majority (64.5%) reported using a serum alcohol level to routinely screen for unhealthy alcohol use; only 23.6% routinely use standardized instruments. Sixty-five percent of ED directors support screening and 70% support intervention among injured ED patients. Only 15% reported having formal screening and intervention policies in their ED, and 9% reported offering brief alcohol intervention by trained personnel. The most commonly perceived barriers to implementation are provider time (83%) and financial resources (55%). Of injured patients identified as exhibiting alcohol misuse, few (12%) receive brief intervention conducted by trained personnel. CONCLUSION: Current alcohol screening and brief intervention practices are lagging behind national guidelines. Although the majority of ED directors support the idea of alcohol screening and intervention, these beliefs have not yet been translated to routine clinical care.

Biomechanics of the Human Brain during Dynamic Rotation of the Head.

Traumatic brain injuries (TBI) are a substantial societal burden. The development of better technologies and systems to prevent and/or mitigate the severity of brain injury requires an improved understanding of the mechanisms of brain injury, and more specifically, how head impact exposure relates to brain deformation. Biomechanical investigations have used computational models to identify these relations, but more experimental brain deformation data are needed to validate these models and support their conclusions. The objective of this study was to generate a dataset describing in situ human brain motion under rotational loading at impact conditions considered injurious. Six head-neck human post-mortem specimens, unembalmed and never frozen, were instrumented with 24 sonomicrometry crystals embedded throughout the parenchyma that can directly measure dynamic brain motion. Dynamic brain displacement, relative to the skull, was measured for each specimen with four loading severities in the three directions of controlled rotation, for a total of 12 tests per specimen. All testing was completed 42-72 h post-mortem for each specimen. The final dataset contains approximately 5,000 individual point displacement time-histories that can be used to validate computational brain models. Brain motion was direction-dependent, with axial rotation resulting in the largest magnitude of displacement. Displacements were largest in the mid-cerebrum, and the inferior regions of the brain-the cerebellum and brainstem-experienced relatively lower peak displacements. Brain motion was also found to be positively correlated to peak angular velocity, and negatively correlated with angular velocity duration, a finding that has implications related to brain injury risk-assessment methods. This dataset of dynamic human brain motion will form the foundation for the continued development and refinement of computational models of the human brain for predicting TBI.

Fetal outcome in motor-vehicle crashes: effects of crash characteristics and maternal restraint.

OBJECTIVE: This project was undertaken to improve understanding of factors associated with adverse fetal outcomes of pregnant occupants involved in motor-vehicle crashes. STUDY DESIGN: In-depth investigations of crashes involving 57 pregnant occupants were performed. Maternal and fetal injuries, restraint information, measures of external and internal vehicle damage, and details about the crash circumstances were collected. Crash severity was calculated using vehicle crush measurements. Chi-square analysis and logistic regression models were used to determine factors with a significant association with fetal outcome. RESULTS: Fetal outcome is most strongly associated with crash severity (P < .001) and maternal injury (P = .002). Proper maternal belt-restraint use (with or without airbag deployment) is associated with acceptable fetal outcome (odds ratio = 4.5, P = .033). Approximately half of fetal losses in motor-vehicle crashes could be prevented if all pregnant women properly wore seat belts. CONCLUSION: Higher crash severity, more severe maternal injury, and lack of proper seat belt use are associated with a higher risk of adverse fetal outcome. These results strongly support recommendations that pregnant women use properly positioned seatbelts.

Postmortem computed tomography as an adjunct to autopsy for analyzing fatal motor vehicle crash injuries: results of a pilot study.

BACKGROUND: Detailed fatal injury data after fatal motor vehicle crashes (MVC) are necessary to improve occupant safety and promote injury prevention. Autopsy remains the principle source of detailed fatal injury data. However, procedure rates are declining because of a range of technical, ethical, and religious concerns. Postmortem computed tomography (PMCT) is a potential alternative or adjunct to autopsy which is increasingly used by forensic researchers. However, there are only limited data regarding the utility of PMCT for analysis of fatal MVC injuries. METHODS: We performed whole body PMCT and autopsy on six subjects fatally injured in MVC in a single county in Michigan. All injuries detected by either method were coded using the Abbreviated Injury Scale (AIS). Severe injuries, defined as AIS 3 or higher (AIS 3+), were tallied for each forensic procedure to allow a comparison of relative diagnostic performance. RESULTS: A total of 46 AIS 3+ injuries were identified by autopsy and PMCT for these cases. The addition of PMCT to autopsy increased overall detection of AIS 3+ injuries (all types) by 28%. PMCT detected 27% more AIS 3+ skeletal injuries than autopsy but 25% less soft tissue injuries. CONCLUSIONS: Use of PMCT improves the detection of AIS 3+ injuries after fatal MVC compared with isolated use of autopsy and also produces a highly detailed permanent objective record. PMCT appears to improve detection of skeletal injury compared with autopsy but is less sensitive than autopsy for the detection of AIS 3+ soft tissue injuries. Neither autopsy nor PMCT identified all AIS 3+ injuries revealed by the combination of the two methodologies. This suggests that PMCT should be used as an adjunct to autopsy rather than a replacement whenever feasible.

Erratum: This Article Corrects: "GLASS Clinical Decision Rule Applied to Thoracolumbar Spinal Fractures in Patients Involved in Motor Vehicle Crashes".

[This corrects the article on p. 1108 in vol. 18, PMID: 29085544.].

Does obesity affect the position of seat belt loading in occupants involved in real-world motor vehicle collisions?

OBJECTIVE: Previous work has shown that the lap belt moves superior and forward compared to the bony pelvis as body mass index (BMI) increases. The goal of this project was to determine whether the location of lap belt loading is related to BMI for occupants who sustained real-world motor vehicle collisions (MVCs). METHODS: A national MVC database was queried for vehicle occupants over a 10-year period (2003-2012) who were at least 16 years old, restrained by a 3-point seat belt, sitting in the front row, and involved in a front-end collision with a change in velocity of at least 56 km/h. Cases were excluded if there was not an available computed tomography (CT) scan of the abdomen. CT scans were then analyzed using adipose enhancement of 3-dimensional reconstructions. Scans were assessed for the presence a radiographic seat belt sign (rSBS), or subcutaneous fat stranding due to seat belt loading. In scans in which the rSBS was present, anterior and superior displacement of rSBS from the anterior-superior iliac spine (ASIS) was measured bilaterally. This displacement was correlated with BMI and injury severity. RESULTS: The inclusion and exclusion criteria yielded 151 cases for analysis. An rSBS could definitively be identified in 55 cases. Cases in which occupants were older and had higher BMI were more likely to display an rSBS. There was a correlation between increasing BMI and anterior rSBS displacement (P <.01 and P <.01, right and left, respectively). There was no significant correlation between BMI and superior displacement of the rSBS (P =.46 and P =.33, right and left, respectively). When the data were examined in terms of relating increasing superior displacement of the lap belt with Injury Severity Scale (P =.34) and maximum Abbreviated Injury Score (AIS) injury severity (P =.63), there was also no significant correlation. CONCLUSION: The results from this study demonstrated that anterior displacement of the radiographic seat belt sign but not superior displacement increased with higher BMI. These results suggest that obesity may worsen horizontal position but not the vertical position of the lap belt loading during real-world frontal MVCs.

GLASS Clinical Decision Rule Applied to Thoracolumbar Spinal Fractures in Patients Involved in Motor Vehicle Crashes.

INTRODUCTION: There are established and validated clinical decision tools for cervical spine clearance. Almost all the rules include spinal tenderness on exam as an indication for imaging. Our goal was to apply GLASS, a previously derived clinical decision tool for cervical spine clearance, to thoracolumbar injuries. GLass intact Assures Safe Spine (GLASS) is a simple, objective method to evaluate those patients involved in motor vehicle collisions and determine which are at low risk for thoracolumbar injuries. METHODS: We performed a retrospective cohort study using the National Accident Sampling System-Crashworthiness Data System (NASS-CDS) over an 11-year period (1998-2008). Sampled occupant cases selected in this study included patients age 16-60 who were belt-restrained, front- seat occupants involved in a crash with no airbag deployment, and no glass damage prior to the crash. RESULTS: We evaluated 14,191 occupants involved in motor vehicle collisions in this analysis. GLASS had a sensitivity of 94.4% (95% CI [86.3-98.4%]), specificity of 54.1% (95% CI [53.2-54.9%]), and negative predictive value of 99.9% (95% CI [99.8-99.9%]) for thoracic injuries, and a sensitivity of 90.3% (95% CI [82.8-95.2%]), specificity of 54.2% (95% CI [53.3-54.9%]), and negative predictive value of 99.9% (95% CI [99.7-99.9%]) for lumbar injuries. CONCLUSION: The GLASS rule represents the possibility of a novel, more-objective thoracolumbar spine clearance tool. Prospective evaluation would be required to further evaluate the validity of this clinical decision rule.

Classifying and Standardizing Panfacial Trauma With a New Bony Facial Trauma Score.

IMPORTANCE: The practice of facial trauma surgery would benefit from a useful quantitative scale that measures the extent of injury. OBJECTIVE: To develop a facial trauma scale that incorporates only reducible fractures and is able to be reliably communicated to health care professionals. DESIGN AND SETTING: A cadaveric tissue study was conducted from October 1 to 3, 2014. Ten cadaveric heads were subjected to various degrees of facial trauma by dropping a fixed mass onto each head. The heads were then imaged with fine-cut computed tomography. A Bony Facial Trauma Scale (BFTS) for grading facial trauma was developed based only on clinically relevant (reducible) fractures. The traumatized cadaveric heads were then scored using this scale as well as 3 existing scoring systems. Regression analysis was used to determine correlation between degree of incursion of the fixed mass on the cadaveric heads and trauma severity as rated by the scoring systems. Statistical analysis was performed to determine correlation of the scores obtained using the BFTS with those of the 3 existing scoring systems. Scores obtained using the BFTS were not correlated with dentition (95% CI, -0.087 to 1.053; P = .08; measured as absolute number of teeth) or age of the cadaveric donor (95% CI, -0.068 to 0.944; P = .08). MAIN OUTCOME MEASURES: Facial trauma scores. RESULTS: Among all 10 cadaveric specimens (9 male donors and 1 female donor; age range, 41-87 years; mean age, 57.2 years), the facial trauma scores obtained using the BFTS correlated with depth of penetration of the mass into the face (odds ratio, 4.071; 95% CI, 1.676-6.448) P = .007) when controlling for presence of dentition and age. The BFTS scores also correlated with scores obtained using 3 existing facial trauma models (Facial Fracture Severity Scale, rs = 0.920; Craniofacial Disruption Score, rs = 0.945; and ZS Score, rs = 0.902; P < .001 for all 3 models). In addition, the BFTS was found to have excellent interrater reliability (0.908; P = .001), which was similar to the interrater reliability of the other 3 tested trauma scales. Scores obtained using the BFTS were not correlated with dentition (odds ratio, .482; 95% CI, -0.087 to 1.053; P = .08; measured as absolute number of teeth) or age of the cadaveric donor (odds ratio, .436; 95% CI, -0.068 to 0.944; P = .08). CONCLUSIONS AND RELEVANCE: Facial trauma severity as measured by the BFTS correlated with depth of penetration of the fixed mass into the face. In this study, the BFTS was clinically relevant, had high fidelity in communicating the fractures sustained in facial trauma, and correlated well with previously validated models. LEVEL OF EVIDENCE: NA.

Small female rib cage fracture in frontal sled tests.

OBJECTIVES: The 2 objectives of this study are to (1) examine the rib and sternal fractures sustained by small stature elderly females in simulated frontal crashes and (2) determine how the findings are characterized by prior knowledge and field data. METHODS: A test series was conducted to evaluate the response of 5 elderly (average age 76 years) female postmortem human subjects (PMHS), similar in mass and size to a 5th percentile female, in 30 km/h frontal sled tests. The subjects were restrained on a rigid planar seat by bilateral rigid knee bolsters, pelvic blocks, and a custom force-limited 3-point shoulder and lap belt. Posttest subject injury assessment included identifying rib cage fractures by means of a radiologist read of a posttest computed tomography (CT) and an autopsy. The data from a motion capture camera system were processed to provide chest deflection, defined as the movement of the sternum relative to the spine at the level of T8. A complementary field data investigation involved querying the NASS-CDS database over the years 1997-2012. The targeted cases involved belted front seat small female passenger vehicle occupants over 40 years old who were injured in 25 to 35 km/h delta-V frontal crashes (11 to 1 o'clock). RESULTS: Peak upper shoulder belt tension averaged 1,970 N (SD = 140 N) in the sled tests. For all subjects, the peak x-axis deflection was recorded at the sternum with an average of -44.5 mm or 25% of chest depth. The thoracic injury severity based on the number and distribution of rib fractures yielded 4 subjects coded as Abbreviated Injury Scale (AIS) 3 (serious) and one as AIS 5 (critical). The NASS-CDS field data investigation of small females identified 205 occupants who met the search criteria. Rib fractures were reported for 2.7% of the female occupants. CONCLUSIONS: The small elderly test subjects sustained a higher number of rib cage fractures than expected in what was intended to be a minimally injurious frontal crash test condition. Neither field studies nor prior laboratory frontal sled tests conducted with 50th percentile male PMHS predicted the injury severity observed. Although this was a limited study, the results justify further exploration of the risk of rib cage injury for small elderly female occupants.

Mass gathering medicine: event factors predicting patient presentation rates.

This study was conducted to identify the event characteristics of mass gatherings that predict patient presentation rates held in a southeastern US university community. We conducted a retrospective review of all event-based emergency medical services (EMS) records from mass gathering patient presentations over an approximate 23 month period, from October 24, 2009 to August 27, 2011. All patrons seen by EMS were included. Event characteristics included: crowd size, venue percentage filled seating, venue location (inside/outside), venue boundaries (bounded/unbounded), presence of free water (i.e., without cost), presence of alcohol, average heat index, presence of climate control (i.e., air conditioning), and event category (football, concerts, public exhibitions, non-football athletic events). We identified 79 mass gathering events, for a total of 670 patient presentations. The cumulative patron attendance was 917,307 persons. The patient presentation rate (PPR) for each event was calculated as the number of patient presentations per 10,000 patrons in attendance. Overdispersed Poisson regression was used to relate this rate to the event characteristics while controlling for crowd size. In univariate analyses, increased rates of patient presentations were strongly associated with outside venues [rate ratio (RR) = 3.002, p < 0.001], unbounded venues (RR = 2.839, p = 0.001), absence of free water (RR = 1.708, p = 0.036), absence of climate control (RR = 3.028, p < 0.001), and a higher heat index (RR = 1.211 per 10-unit heat index increase, p = 0.003). The presence of alcohol was not significantly associated with the PPR. Football events had the highest PPR, followed sequentially by public exhibitions, concerts, and non-football athletic events. In multivariate models, the strong predictors from the univariate analyses retained their predictive significance for the PPR, together with heat index and percent seating. In the setting of mass event medical care, we note that several factors are strongly associated with an increased patient census, including outside (external) or unbounded venues, the absence of fee water (i.e., without cost), no climate control, percent (occupied) seating, and increasing heat index. Although the presence of alcohol is noted to increase patient needs, it does not do so significantly. Regarding event type, collegiate football games have the highest patient census among the range of other events studied. These findings should be considered during the process of EMS resource planning for mass gatherings.