Dorion Wiley

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.

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.

Screening for traumatic stress among survivors of urban trauma.

OBJECTIVE This study piloted the use of the Primary Care PTSD (PC-PTSD) screening tool in an outpatient setting to determine its utility for broader use and to gather data on traumatic stress symptoms among direct (patients) and indirect (families) survivors of traumatic injuries. METHODS Using the PC-PTSD plus one question exploring openness to seeking help, participants were screened for PTSD in the outpatient clinic of an urban Level 1 trauma center. The survey was distributed during a 23-week period from April to September 2011. The screen was self-administered, a sample of convenience, and participation was voluntary and anonymous. RESULTS With a response rate of 66%, 307 surveys were completed. Forty-two percent of participants had a positive screen. Patients greater than 30 and 90 days from injury had 1.5 and 1.7 times more positive screens than those less than 30 days. Patients with gunshot wounds were 13 times as likely as those with falls and twice as likely as those in a motor vehicle crash to have a positive screen. Sixty percent of patients with a positive screen noted it would be helpful to talk to someone. CONCLUSION The PC-PTSD was an easy to administer screening tool. Patients reported PTSD symptoms at higher rates than previous studies. Patients with gunshot wounds and those injured greater than 30 days from the time of the screen were more likely to report PTSD symptoms. Although males represented 82% of positive screens, there was no statistical difference in PTSD symptoms between male and female participants because of the small number of females represented. Families also reported significant levels of PTSD. Both patients and families may benefit from additional screening and intervention in the early posttrauma period. LEVEL OF EVIDENCE Epidemiologic study, level IV.

Not so fast to skin graft: Transabdominal wall traction closes most ''domain loss'' abdomens in the acute setting

BACKGROUND Damage-control laparotomy (DCL) has revolutionized the surgery of injury. However, this has led to the dilemma of the nonclosable abdomen. Subsequently, there exists a subgroup of patients who after resuscitation and diuresis, remain nonclosable. Before the adoption of our open abdomen protocol (OAP) and use of transabdominal wall traction (TAWT), these patients required skin grafting and a planned ventral hernia. We hypothesize that our OAP and TAWT device, which use full abdominal wall thickness sutures to dynamically distribute midline traction, achieve an improved method of fascial reapproximation. METHODS From 2008 to 2011, all DCL and decompressive laparotomy patients in our urban trauma center were managed by our OAP. Thirty two were noncloseable “domain loss abdomens” after achieving physiologic steady state and near dry weight. All patients received the TAWT device when near dry weight was achieved. Wound size, days to closure, days to TAWT, and TAWT to closure were tracked. RESULTS During this 36-month period, OAP/TAWT was applied to 32 patients. All patients demonstrated domain loss precluding fascial closure. Average wound size was 18.5-cm width by 30.5-cm length. Mean time DCL surgery to TAWT was 9.5 days. At time of placement, TAWT decreased initial wound width by an average of 9.8 cm (51.4%). Patients returned to the operating room for tightening/washout an average of 2.2 times (excluding TAWT insertion and final closure operations). Mean time TAWT to closure was 8.7 days. Mean time from admission surgery to primary closure was 18.2 days. All patients achieved primary fascial closure using this method without components separation or biologic bridge operations. CONCLUSION OAP/TAWT has revolutionized the way we manage “domain loss” open abdomen patients and has virtually eliminated the acceptance of planned ventral hernia. TAWT consistently recaptures lost domain, preserves the leading fascial edge, and eliminates the need for biologic bridges, components separation, or skin grafting. LEVEL OF EVIDENCE Therapeutic study, level III.

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.

Hyperthermic resuscitation is safe and effective after hemorrhagic shock in dogs.

OBJECTIVE To show that resuscitation from hypothermic, hemorrhagic shock using 65 degrees C intravenous fluid results in a more rapid return to euthermia compared with 40 degrees C intravenous fluid, without significant endothelial or hemolytic injury. DESIGN Fourteen anesthetized beagles (10-12 kg) were cooled to a core temperature of 30 degrees C and hemorrhaged to a mean arterial pressure of 40 to 45 mm Hg for 30 minutes. The animals were randomized to receive either 65 degrees C or 40 degrees C intravenous fluid through a specially designed catheter at a rate of 80% of their blood volume per hour until euthermic (37 degrees C) or for 2 hours. MATERIALS AND METHODS Blood pressure, pulmonary artery pressure, heart rate, and core temperature were continuously monitored. Blood samples were collected at baseline, after hemorrhage, 2 hours of resuscitation, and at postmortem examination after 7 days of survival. Laboratory measurements included complete blood count, plasma-free hemoglobin, and osmotic fragility. Values were compared using the Students paired or unpaired t test with p approximately 0.05 indicating significance. Postmortem examination included light microscopy of the proximal superior vena cava or right atrium. RESULTS Animals receiving 65 degrees C intravenous fluid warmed 3.6 degrees C/hour, significantly faster than the 40 degrees C animals (1.9 degrees C/hour). There were no significant differences in plasma-free hemoglobin or osmotic fragility. Endothelial injuries were found in two animals in each group. These defects occurred along the path of catheter insertion and not at the infusion site. CONCLUSIONS Central intravenous fluid at 65 degrees C is a more rapid means of treating hypothermia than standard 40 degrees C intravenous fluid. It is safe even in hypovolemic animals.

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. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.