When public health crises collide: 5 years of pediatric firearm injury prevention opportunities.

Objectives: Prior publications on pediatric firearm-related injuries have emphasized significant social disparities. The pandemic has heightened a variety of these societal stresses. We sought to evaluate how we must now adapt our injury prevention strategies. Patients and methods: Firearm-related injuries in children 15 years old and under at five urban level 1 trauma centers between January 2016 and December 2020 were retrospectively reviewed. Age, gender, race/ethnicity, Injury Severity Score, situation, timing of injury around school/curfew, and mortality were evaluated. Medical examiner data identified additional deaths. Results: There were 615 injuries identified including 67 from the medical examiner. Overall, 80.2% were male with median age of 14 years (range 0-15; IQR 12-15). Black children comprised 77.2% of injured children while only representing 36% of local schools. Community violence (intentional interpersonal or bystander) injuries were 67.2% of the cohort; 7.8% were negligent discharges; and 2.6% suicide. Median age for intentional interpersonal injuries was 14 years (IQR 14-15) compared with 12 years (IQR 6-14, p<0.001) for negligent discharges. Far more injuries were seen in the summer after the stay-at-home order (p<0.001). Community violence and negligent discharges increased in 2020 (p=0.004 and p=0.04, respectively). Annual suicides also increased linearly (p=0.006). 5.5% of injuries were during school; 56.7% after school or during non-school days; and 34.3% were after legal curfew. Mortality rate was 21.3%. Conclusions: Pediatric firearm-related injuries have increased during the past 5 years. Prevention strategies have not been effective during this time interval. Prevention opportunities were identified specifically in the preteenage years to address interpersonal de-escalation training, safe handling/storage, and suicide mitigation. Efforts directed at those most vulnerable need to be reconsidered and examined for their utility and effectiveness. Level of evidence: Level III; epidemiological study type.

The Windlass Tourniquet: Is It Taking the Wind Out of the "Stop the Bleed" Sails?

BACKGROUND: Civilians are often first-line responders in hemorrhage control; however, windlass tourniquets are not intuitive. Untrained users reading enclosed instructions failed in 38.2% of tourniquet applications. This prospective follow-up study replicated testing following Stop the Bleed (STB) training. MATERIALS AND METHODS: One and six months following STB, first-year medical students were randomly assigned a windlass tourniquet with enclosed instructions. Each was given one minute to read instructions and two minutes to apply the windlass tourniquet on the TraumaFX HEMO trainer. Demographics, time to read instructions and stop bleeding, blood loss, and simulation success were analyzed. RESULTS: 100 students received STB training. 31 and 34 students completed tourniquet testing at one month and six months, respectively. At both intervals, 38% of students were unable to control hemorrhage (P = 0.97). When compared to the pilot study without STB training (median 48 sec, IQR 33-60 sec), the time taken to read the instructions was shorter one month following STB (P <0.001), but there was no difference at 6 months (P = 0.1). Incorrect placement was noted for 19.4% and 23.5% of attempts at 1 and 6 months. Male participants were more successful in effective placement at one month (93.3% versus 31.3%, P = 0.004) and at six months (77.8% versus 43.8%, p = 0.04). CONCLUSIONS: Skills decay for tourniquet application was observed between 1 and 6 months following STB. Instruction review and STB produced the same hemorrhage control rates as reading enclosed instructions without prior training. Training efforts must continue; but an intuitive tourniquet relying less on mechanical advantage is needed.

Pediatric Firearm-Related Injuries: Taking Kids Out of Harm's Way Begins with Targeted Prevention.

BACKGROUND: Firearm-related injury is a public health crisis and remains the 3rd most common cause of death from ages 1 15 years. By evaluating events surrounding such injuries, evidence-based intervention strategies efforts may be targeted to maximize impact. MATERIAL AND METHODS: A retrospective chart review was performed for firearm-related injuries in patients 15 years-old and under at an urban Pediatric Level 1 Trauma Center between January 2016 and December 2020. Age, gender, race/ethnicity, injury severity score (ISS), reported cause of injury, timing of injury around school and curfew, and mortality were evaluated. Medical Examiner data identified other deaths that occurred within the hospital's catchment area. RESULTS: There were 195 injuries including 14 from the Medical Examiner. Overall, 82.6% were male with median age of 14 years (range 1-15; IQR 13-15), and median ISS of 5 (IQR 1-10). African-American children comprised 74.9% of the cohort while only representing 35.9% of local schools. Intentional interpersonal injuries comprised 65.6%; 17.4% were bystanders; 7.2% were negligent discharges; and 0.5% suicide. Median age for intentional interpersonal injuries was 14 years (IQR 13-15) compared to 11 years (IQR 8-14, P = 0.03) for negligent discharges. Regarding timing, 6.9% of injuries occurred during school hours; 56.4% after school or during non-school days; and 36.7% were after legal curfew. Mortality rate was 17.4%. CONCLUSIONS: Firearm safety education and community-based violence intervention should start in the pre-teen years. Pediatric firearm-related injury prevention strategies must be multifaceted addressing structural racism, truancy, curfew violation, extra-curricular activities, childcare options, firearm safety education, violence reduction, suicide prevention, and recidivism.

Isolating Populations to Control Pandemic Spread in an Austere Military Environment.

BACKGROUND: The COVID-19 pandemic has been a struggle for medical systems throughout the world. In austere locations in which testing, resupply, and evacuation have been limited or impossible, unique challenges exist. This case series demonstrates the importance of population isolation in preventing disease from overwhelming medical assets. METHODS: This is a case series describing the outbreak of COVID-19 in an isolated population in Africa. The population consists of a main population with a Role 2 capability, with several supported satellite populations with a Role 1 capability. Outbreaks in five satellite population centers occurred over the course of the COVID-19 pandemic from its start on approximately 1 March 2020 until 28 April 2020, when a more robust medical asset became available at the central evacuation hub within the main population. RESULTS: Population movement controls and the use of telehealth prevented the spread within the main population at risk and enabled the setup of medical assets to prepare for anticipated widespread disease. CONCLUSION: Isolation of disease in the satellite populations and treating in place, rather than immediately moving to the larger population center's medical facilities, prevented widespread exposure. Isolation also protected critical patient transport capabilities for use for high-risk patients. In addition, this strategy provided time and resources to develop infrastructure to handle anticipated larger outbreaks.

Bronchoalveolar lavage and plasma Antithrombin and cytokines in inhalation and burn injury: a pilot study.

Systemic inflammatory response syndrome (SIRS) is initiated during the acute phase of thermal injury. The objective was to determine the SIRS impact on cytokine and Antithrombin (AT) levels in smoke inhalation and burn injury. This observational pilot study compared plasma and bronchoalveolar lavage fluid (BAL) cytokine and AT levels in the first six days post smoke inhalation and burn injury. Twenty-five patients, 14 with inhalation + burn injury > 10% total body surface area (TBSA) and 11 with inhalation injury and ≤ 10% TBSA participated. Human Th1/Th2 cytometric bead array kit from BD Biosciences Pharmingen determined cytokine levels; AT levels with Sigma Diagnostics and spectrophotometry. Results indicated no significant age difference between the two groups (42.1 ± 7.2) versus 49.6 ± 6.4 years. On admission, the inhalation group had 5.4 ± 3.9% TBSA compared to 35.0 ± 22.2% TBSA in the inhalation + burn group, P < 0.001. Comparing groups, AT plasma levels were significantly decreased (P = 0.025) and IL-2 levels significantly increased (P = 0.025) in the inhalation + burn group compared to the inhalation group; there was no significant difference in BAL AT or cytokine levels. Combined group plasma AT levels (65.41 ± 4.44%) were significantly increased compared to BAL AT levels (1.06 ± 0.71%), P < 0.001. In contrast, BAL TNF-α levels (35.61 ± 16.01 pg/ml) were significantly increased in relation to the plasma levels (4.68 ± 1.27 pg/ml), P = 0.02. On days 1-2, AT plasma levels were significantly decreased in the inhalation + burn group (41.01 ± 5.24%) compared to the inhalation group (81.02 ± 10.99%), P = 0.002. IL-6 plasma levels were higher in the inhalation + burn group compared to the inhalation group on admission, but both levels decreased by days 3-6. IL-6 BAL levels were elevated in both groups on days 1-2 and decreased by days 3-6. In the first six days of resuscitation, all plasma cytokines were increased in the two groups compared to controls. AT plasma and BAL levels were significantly reduced in both groups, contributing to the coagulopathy. Increased BAL TNF-α and IL-6 levels may have contributed to the pulmonary perturbations during the initial SIRS response in both groups.

The scales of recovery: Balancing posttraumatic stress with resilience in the violently injured.

BACKGROUND: Community violence remains a clinical concern for urban hospitals nationwide; however, research on resilience and posttraumatic growth (PTG) among survivors of violent injury is lacking. This study intends to assess survivors of violent injury for resilience and PTG to better inform mental health interventions. METHODS: Adults who presented with nonaccidental penetrating trauma to an urban level 1 trauma center and were at least 1 month, but no more than 12 months, from treatment were eligible. Participants completed the Connor-Davidson Resiliency Scale, Posttraumatic Growth Inventory (PTGI), Primary Care Posttraumatic Stress Disorder screen, and a community violence exposure screen. Additional demographic, injury, and treatment factors were collected from medical record. RESULTS: A total of 88 patients participated. The mean resiliency score was 83.2, with 71.1% scoring higher than the general population and 96.4% scoring higher than the reported scores of those seeking treatment for posttraumatic stress disorder (PTSD). Participants demonstrated a mean PTGI score of 78 (SD, 20.4) with 92.4% scoring above the significant growth threshold of 45. In addition, 60.5% of patients screened positive for significant PTSD symptoms, approximately eight times higher than general population. Exposure to other traumatic events was high; an overwhelming 94% of participants stated that they have had a family member or a close friend killed, and 42% had personally witnessed a homicide. Higher resilience scores correlated with PTGI scores (p < 0.001) and lower PTSD screen (p = 0.02). CONCLUSION: Victims of violent injury experience a myriad of traumatic events yet are highly resilient and exhibit traits of growth across multiple domains. Resiliency can coexist with posttraumatic stress symptoms. Practitioners should assess for resiliency and PTG in addition to PTSD. Further investigation is needed to clarify the relational balance between resilience and posttraumatic stress. LEVEL OF EVIDENCE: Epidemiological study type, Level II.

Does Pain Have a Role When It Comes to Tourniquet Training?

BACKGROUND: One of the greatest conundrums with tourniquet (TQ) education is the use of an appropriate surrogate of hemorrhage in the training setting to determine whether a TQ has been successfully used. At our facility, we currently use loss of audible Doppler signal or loss of palpable pulse to represent adequate occlusion of vasculature and thus successful TQ application. We set out to determine whether pain can be used to indicate successful TQ application in the training setting. METHODS: Three tourniquet systems (a pneumatic tourniquet, Combat Application Tourniquet® [C-A-T], and Stretch Wrap and Tuck Tourniquet™ [SWAT-T]) were used to occlude the arterial vasculature of the left upper arm (LUA), right upper arm (RUA), left forearm (LFA), right forearm (RFA), right thigh (RTH), and right calf (RCA) of 41 volunteers. A 4MHz, handheld Doppler ultrasound was used to confirm loss of Doppler signal (LOS) at the radial or posterior tibial artery to denote successful TQ application. Once successful placement of the TQ was noted, subjects rated their pain from 0 to 10 on the visual analog scale. In addition, the circumference of each limb, the pressure with the pneumatic TQ, number of twists with the C-A-T, and length of TQ used for the SWAT-T to obtain LOS was recorded. RESULTS: All 41 subjects had measurements at all anatomic sites with the pneumatic TQ, except one participant who was unable to complete the LUA. In total, pain was rated as 1 or less by 61% of subjects for LUA, 50% for LFA, 57.5% for RUA, 52.5% RFA, 15% for RTH, and 25% for RCA. Pain was rated 3 or 4 by 45% of subjects for RTH. For the C-A-T, data were collected from 40 participants. In total, pain was rated as 1 or less by 57.5% for the LUA, 70% for the LFA, 62.5% for the RUA, 75% for the RFA, 15% for the RTH, and 40% for the RCA. Pain was rated 3 or 4 by 42.5%. The SWAT-T group consisted of 37 participants for all anatomic locations. In total, pain was rated as 1 or less by 27% for LUA, 40.5% for the LFA, 27.0% for the RUA, 43.2 for the RFA, 18.9% for the RTH, and 16.2% for the RCA. Pain was rated 5 by 21.6% for RTH application, and 3 or 4 by 35%. CONCLUSION: The unexpected low pain values recorded when loss of signal was reached make the use of pain too sensitive as an indicator to confirm adequate occlusion of vasculature and, thus, successful TQ application.

Hemorrhage control by law enforcement personnel: a survey of knowledge translation from the military combat experience.

BACKGROUND: Military data demonstrate that exsanguinating hemorrhage is the leading cause of potentially preventable combat death. The purpose of this study was to evaluate attitudes and approaches of civilian law enforcement personnel in the management of acute hemorrhagic trauma. METHODS: Anonymous survey administered via an online distribution mechanism. RESULTS: 1,317 U.S. law enforcement personnel began the survey. 370 respondents (30.4%) reported their agencies issued tourniquets, whereas 48.8% indicated their agencies had provided specific training in tourniquet application. Pressure dressings were provided to 43.6% of respondents while hemostatic agents were available to 29.8%. Tourniquets were considered the intervention most likely to save a life, but were also deemed most likely to possibly cause harm or injury if used inappropriately. 43 respondents (0.036%) stated they were aware of circumstances within the past year in which an officer in their agency sustained injuries where a tourniquet could have been used, but was not. CONCLUSIONS: Hemorrhage control supplies are being issued to less than half of the responding officers. When used, these interventions were generally thought to be effective. Further study is needed to delineate specific medical interventions, and therefore training and equipment, needed by law enforcement personnel.

Trans-abdominal wall traction as a universal solution to the management of giant ventral hernias.

BACKGROUND: Domain loss following damage-control laparotomy is a challenging problem many surgeons face. The authors recently developed trans-abdominal wall traction, which closed 100 percent of domain loss abdomens in the acute setting. They hypothesized that it can be used successfully in patients with chronic giant ventral defects. METHODS: From 2008 to 2013, 44 patients with acute loss of domain and 10 with chronically giant ventral defects were enrolled in the open abdomen protocol with subsequent placement of the trans-abdominal wall traction device. RESULTS: Patients' average age in the acute and chronic groups was 28.2 and 35.3 years and average body mass index was 26.4 and 32.4 kg/m2, respectively. Ventral hernia size was reduced with the first trans-abdominal wall traction insertion from 610.5 cm2 to 274.6 cm2 in the acute setting and from 598 cm2 to 236.9 cm2 in the chronic setting. Average time from damage-control laparotomy to device insertion was 12.9 days in the acute group and more than 3 years in the chronic group. Lost domain was achieved with an average of less than 2.5 trans-abdominal wall traction tightenings, correlating to 9.2 and 8.2 days in the acute and chronic groups, respectively. Enterocutaneous fistula occurrence was 9 percent in the acute group and 0 percent in the chronic group. CONCLUSIONS: All patients were successfully closed after reestablishment of the lost domain. Trans-abdominal wall traction is an effective means of reestablishing abdominal domain and achieving primary abdominal wall closure in all patients with giant ventral defects, both acute and chronic.

Are general surgeons behind the curve when it comes to disaster preparedness training? A survey of general surgery and emergency medicine trainees in the United States by the Eastern Association for the Surgery for Trauma Committee on Disaster Preparedness.

PURPOSE: We think that general surgeons are underprepared to respond to mass casualty disasters. Preparedness education is required in emergency medicine (EM) residencies, yet such requirements are not mandated for general surgery (GS) training programs. We hypothesize that EM residents receive more training, consider themselves better prepared, and are more comfortable responding to disaster events than are GS residents. METHODS: From February to May 2009, the Eastern Association for the Surgery of Trauma-Committee on Disaster Preparedness conducted a Web-based survey cataloging training and preparedness levels in both GS and EM residents. Approximately 3000 surveys were sent. Chi-squared, logistic regression, and basic statistical analyses were performed with SAS. RESULTS: Eight hindered forty-eight responses were obtained, GS residents represented 60.6% of respondents with 39% EM residents, and four residents did not respond with their specialty (0.4%). We found significant disparities in formal training, perceived preparedness, and comfort levels between resident groups. Experience in real-life disaster response had a significant positive effect on comfort level in all injury categories in both groups (odds ratio, 1.3-4.3, p < 0.005). CONCLUSION: This survey confirms that EM residents have more disaster-related training than GS residents. The data suggest that for both groups, comfort and confidence in treating victims were not associated with training but seemed related to previous real-life disaster experience. Given wide variations in the relationship between training and comfort levels and the constraints imposed by the 80-hour workweek, it is critical that we identify and implement the most effective means of training for all residents.

Taser X26 discharges in swine: ventricular rhythm capture is dependent on discharge vector.

BACKGROUND: Data from our previous studies indicate that Taser X26 stun devices can acutely alter cardiac function in swine. We hypothesized that most transcardiac discharge vectors would capture ventricular rhythm, but that other vectors, not traversing the heart, would fail to capture the ventricular rhythm. METHODS: Using an Institutional Animal Care and Use Committee (IACUC) approved protocol, four Yorkshire pigs (25-36 kg) were anesthetized, paralyzed with succinylcholine (2 mg/kg), and then exposed to 10 second discharges from a police-issue Taser X26. For most discharges, the barbed darts were pushed manually into the skin to their full depth (12 mm) and were arranged in either transcardiac (such that a straight line connecting the darts would cross the region of the heart) or non-transcardiac vectors. A total of 11 different vectors and 22 discharge conditions were studied. For each vector, by simply rotating the cartridge 180-degrees in the gun, the primary current-emitting dart was changed and the direction of current flow during the discharge was reversed without physically moving the darts. Echocardiography and electrocardiograms (ECGs) were performed before, during, and after all discharges. p values < 0.05 were considered significant. RESULTS: ECGs were unreadable during the discharges because of electrical interference, but echocardiography images clearly demonstrated that ventricular rhythm was captured immediately in 52.5% (31 of 59) of the discharges on the ventral surface of the animal. In each of these cases, capture of the ventricular rhythm with rapid ventricular contractions consistent with ventricular tachycardia (VT) or flutter was seen throughout the discharge. A total of 27 discharges were administered with transcardiac vectors and ventricular capture occurred in 23 of these discharges (85.2% capture rate). A total of 32 non-transcardiac discharges were administered ventrally and capture was seen in only eight of these (25% capture rate). Ventricular fibrillation (VF) was seen with two vectors, both of which were transcardiac. In the remaining animals, VT occurred postdischarge until sinus rhythm was regained spontaneously. CONCLUSIONS: For most transcardiac vectors, Taser X26 caused immediate ventricular rhythm capture. This usually reverted spontaneously to sinus rhythm but potentially fatal VF was seen with two vectors. For some non-transcardiac vectors, capture was also seen but with a significantly (p < 0.0001) decreased incidence.

Acute effects of MK63 stun device discharges in miniature swine.

OBJECTIVE: Electromuscular incapacitation (EMI) devices are being used and evaluated by both military and law enforcement agencies. Although the gross muscular response is obvious, physiological responses to these devices are poorly understood. We hypothesized that the intense, repetitive, muscle contractions evoked by EMI devices would cause dose-dependent metabolic acidosis, accompanied by neuromuscular or cardiac injury. METHODS: Using an approved protocol, 26 Yucatan mini-pigs (22 experimental animals and 4 control animals) were anesthetized with ketamine and xylazine. Experimental animals were exposed to MK63 (Aegis Industries, Bellevue, Idaho) discharges over the left anterior hind limb for 10, 20, 40, or 80 seconds. Electrocardiograms, electromyograms, troponin I levels, blood gas values, and electrolyte levels were recorded before and 5, 15, 30, and 60 minutes and 24, 48, and 72 hours after discharge. Skin, muscle, and nerve biopsies were taken from the shocked and contralateral sides. RESULTS: Core body temperature significantly decreased (1.0-1.5 degrees C) in all shocked animals but not in sham-treated control animals. No cardiac dysrhythmias or deaths were seen, and heart rate was unaffected. No clinically significant changes were seen in troponin I, myoglobin, or creatine kinase-MB levels. Central venous blood pH decreased, whereas carbon dioxide pressure and lactate levels increased for 60 minutes after discharge. All values returned to normal by 24 hours after discharge, and no significant histological or electromyographic changes were found. CONCLUSIONS: Changes in blood chemistry were observed but were of little clinical significance, and no neuromuscular damage was detected. Therefore, within the limitations of this model, it appears that EMI can safely be achieved by using this device, even for lengthy periods, without causing significant injury.

TASER X26 discharges in swine produce potentially fatal ventricular arrhythmias.

OBJECTIVES: Data from the authors and others suggest that TASER X26 stun devices can acutely alter cardiac function in swine. The authors hypothesized that TASER discharges degrade cardiac performance through a mechanism not involving concurrent acidosis. METHODS: Using an Institutional Animal Care and Use Committee (IACUC)-approved protocol, Yorkshire pigs (25-71 kg) were anesthetized, paralyzed with succinylcholine (SCh; 2 mg/kg), and then exposed to two 40-second discharges from a TASER X26 with a transcardiac vector. Vital signs, blood chemistry, and electrolyte levels were obtained before exposure and periodically for 48 hours postdischarge. Electrocardiograms and echocardiography (echo) were performed before, during, and after the discharges. p-Values < 0.05 were considered significant. RESULTS: Electrocardiograms were unreadable during the discharges due to electrical interference, but echo images showed unmistakably that cardiac rhythm was captured immediately at a rate of 301 +/- 18 beats/min (n = 8) in all animals tested. Capture continued for the duration of the discharge and in one animal degenerated into fatal ventricular fibrillation (VF). In the remaining animals, ventricular tachycardia (VT) occurred postdischarge for 1-17 seconds, whereupon sinus rhythm was regained spontaneously. Blood chemistry values and vital signs were minimally altered postdischarge and no significant acidosis was seen. CONCLUSIONS: Extreme acid-base disturbances usually seen after lengthy TASER discharges were absent with SCh, but TASER X26 discharges immediately and invariably produced myocardial capture. This usually reverted spontaneously to sinus rhythm postdischarge, but fatal VF was seen in one animal. Thus, in the absence of systemic acidosis, lengthy transcardiac TASER X26 discharges (2 x 40 seconds) captured myocardial rhythm, potentially resulting in VT or VF in swine.

Acute effects of TASER X26 discharges in a swine model.

BACKGROUND: Very little objective laboratory data are available describing the physiologic effects of stun guns or electromuscular incapacitation devices (EIDs). Unfortunately, there have been several hundred in-custody deaths, which have been temporally associated with the deployment of these devices. Most of the deaths have been attributed to specific cardiac and metabolic effects. We hypothesized that prolonged EID exposure in a model animal system would induce clinically significant metabolic acidosis and cardiovascular disturbances. METHODS: Using an Institutional Animal Care and Use Committee-approved protocol, 11 standard pigs (6 experimentals and 5 sham controls) were anesthetized with ketamine and xylazine. The experimentals were exposed to two 40-second discharges from an EID (TASER X26, TASER Intl., Scottsdale, AZ) across the torso. Electrocardiograms, blood pressure, troponin I, blood gases, and electrolyte levels were obtained pre-exposure and at 5, 15, 30, and 60 minutes and 24, 48, and 72 hours postdischarge. p values <0.05 were considered significant. RESULTS: Two deaths were observed immediately after TASER exposure from acute onset ventricular fibrillation (VF). In surviving animals, heart rate was significantly increased and significant hypotension was noted. Acid-base status was dramatically affected by the TASER discharge at the 5-minute time point and throughout the 60-minute monitoring period. Five minutes postdischarge, central venous blood pH (6.86 +/- 0.07) decreased from baseline (7.45 +/- 0.02; p = 0.0004). Pco2 (94.5 mm Hg +/- 14.8 mm Hg) was significantly increased from baseline (45.3 mm Hg +/- 2.6 mm Hg) and bicarbonate levels significantly decreased (15.7 mmol/L +/- 1.04 mmol/L) from baseline (30.4 mmol/L +/- 0.7 mmol/L). A large, significant increase in lactate occurred postdischarge (22.1 mmol/L +/- 1.5 mmol/L) from baseline (1.5 mmol/L +/- 0.3 mmol/L). All values returned to normal by 24 hours postdischarge in surviving animals. A minor, nonsignificant increase in troponin I was seen at 24 hours postdischarge (0.052 ng/mL +/- 0.030 ng/mL, mean +/- SEM). CONCLUSIONS: Immediately after the discharge, two deaths occurred because of ventricular fibrillation. In this model of prolonged EID exposure, clinically significant acid-base and cardiovascular disturbances were clearly seen. The severe metabolic and respiratory acidosis seen here suggests the involvement of a primary cardiovascular mechanism.

Neuromuscular effects of stun device discharges.

BACKGROUND: Stun guns or electromuscular incapacitation devices (EMIs) generate between 25,000 and 250,000 V and can be discharged continuously for as long as 5 to 10 min. In the United States, over 200,000 individuals have been exposed to discharges from the most common type of device used. EMI devices are being used increasingly despite a lack of objective laboratory data describing the physiological effects and safety of these devices. An increasing amount of morbidity, and even death, is associated with EMI device use. To examine this type of electrical injury, we hypothesized that EMI discharges will induce acute or delayed cardiac arrhythmia and neuromuscular injury in an animal model. METHODS: Using an IACUC approved protocol, from May 2005 through June 2006 in a teaching hospital research setting, 30 Yucatan mini-pigs (24 experimentals and 6 sham controls) were deeply anesthetized with ketamine and xylazine without paralytics. Experimentals were exposed to discharges from an EID (MK63; Aegis Industries, Bellevue, ID) over the femoral nerve on the anterior left hind limb for an 80 s exposure delivered as two 40 s discharges. EKGs, EMGs, troponin I, CK-MB, potassium, and myoglobin levels were obtained pre-discharge and post-discharge at 5, 15, 30, and 60 min, 24, 48, and 72 h (n = 6 animals) and 5, 15, and 30 d post-discharge (n = 6 animals at each time point). Skin, skeletal muscle, and peripheral nerve biopsies were studied bilaterally. Data were compared using one-way analysis of variance and paired t-tests. P-values <0.05 were considered significant. RESULTS: No cardiac arrhythmias or sudden deaths were seen in any animals at any time point. No evidence of skeletal muscle damage was detected. No significant changes were seen in troponin I, myoglobin, CK-MB, potassium, or creatinine levels. There were no significant changes in compound muscle action potentials (CMAP). No evidence of conduction block, conduction slowing, or axonal loss were detected on EMG. M-wave latency (M(lat), ms), amplitude (M(amp), mV), area (M(area), mV-ms), and duration (M(dur), ms) were not significantly affected by MK63 discharge compared with contralateral or sham controls. F-wave latency (F(lat), ms), a sensitive indicator of retrograde nerve conduction and function, was not significantly affected by MK63 discharge compared with contralateral or sham controls. No significant histological changes were seen at any time point in skeletal muscle or peripheral nerve biopsies although mild skin inflammation was evident. CONCLUSIONS: There was no evidence of acute arrhythmia from MK63 discharges. No clinically significant changes were seen in any of the physiological parameters measured here at any time point. Neuromuscular function was not significantly altered by the MK63 discharge. In this animal model, even lengthy MK63 discharges did not induce muscle or nerve injury as seen using EMG, blood chemistry, or histology.

Repeated thoracic discharges from a stun device.

BACKGROUND: Little objective laboratory data are available describing the physiologic effects of stun guns or electromuscular incapacitation (EMI) devices, but increasing morbidity and even deaths are associated with their use. We hypothesized that exposure to EMI discharges in a model animal system would induce clinically significant acidosis and cardiac arrhythmia. METHODS: Ten Yucatan mini-pigs, six experimental and four sham controls, were anesthetized with ketamine, xylazine, and glycopyrrolate. Experimental pigs were exposed to two 40-second discharges from an EMI device over the left thorax. Electrocardiograms, troponin I, blood gases, and lactate levels were obtained pre-exposure, at 5, 15, 30, 60 minutes, and at 24, 48, and 72 hours postdischarge. RESULTS: No acute or delayed cardiac arrhythmias were seen. Heart rate was not affected significantly (p>0.05). A subclinical increase in troponin I was seen at 24 hours postdischarge (0.040+/-0.030 ng/mL, p>0.05). Central venous blood pH (7.432+/-0.014) and pCO2 (36.1+/-0.9 mm Hg) were not changed significantly (p>0.05) during the 60-minute postdischarge period. A moderate significant increase in lactate occurred in the 5-minute postdischarge group (4.9+/-0.3 mmol/L, p=0.0179). All blood chemistry and vital signs were normal at 24, 48, and 72 hours postdischarge. CONCLUSIONS: Although significant changes in some parameters were seen, these changes were small and of little clinical significance. Lengthy EMI exposures did not cause extreme acidosis or cardiac arrhythmias. These findings may differ from those seen with other EMI devices because of the unique MK63 waveform characteristics or to specific characteristics of the model systems.

Reducing complexity when studying seed dispersal at community scales: a functional classification of vertebrate seed dispersers in tropical forests.

The process of seed dispersal has a profound effect on vegetation structure and diversity in tropical forests. However, our understanding of the process and our ability to predict its outcomes at a community scale are limited by the frequently large number of interactions associated with it. Here, we outline an approach to dealing with this complexity that reduces the number of unique interactions considered by classifying the participants according to their functional similarity. We derived a classification of dispersers based on the nature of the dispersal service they provide to plants. We described the quantities of fruit handled, the quality of handling and the diversity of plants to which the service is provided. We used ten broad disperser traits to group 26 detailed measures for each disperser. We then applied this approach to vertebrate dispersers in Australia's tropical forests. Using this we also develop a classification that may be more generally applicable. For each disperser, data relating to each trait was obtained either from the field or published literature. First, we identified dispersers whose service outcomes were so distinct that statistical analysis was not required and assigned them to functional groups. The remaining dispersers were assigned to functional groups using cluster analysis. The combined processes created 15 functional groups from 65 vertebrate dispersers in Australian tropical forests. Our approach--grouping dispersers on the basis of the type of dispersal service provided and the fruit types it is provided to--represents a means of reducing the complexity encountered in tropical seed dispersal systems and could be effectively applied in community level studies. It also represents a useful tool for exploring changes in dispersal services when the distribution and abundance of animal populations change due to human impacts.