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.

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.

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.

Comparison of dermal substitutes in wound healing utilizing a nude mouse model.

BACKGROUND: Dermal skin substitutes have become a standard of care in burn treatment. OBJECTIVE: To compare and assess wound contracture reduction and histologic incorporation into the wound, dermal substitutes were implanted into full-thickness skin wounds in nude mice. MATERIALS AND METHODS: Thirty-seven mice received a full-thickness 2 x 2 cm dorsal skin wound, and were either implanted with an acellular dermal matrix, Alloderm, Dermagraft-TC, Dermalogen, or Integra or assigned to the control group (with no dermal substitute). At 28 days postsurgery, the wounds were assessed for contraction, epithelialization, and other histological characteristics. RESULTS: Each dermal substitute decreased wound contracture, but Alloderm and the acellular dermal matrix did so significantly compared to the control (P < .01 and P < .03, respectively). Within-group and control comparisons showed no significant differences with respect to the presence of dystrophic calcification, squamous hyperplasia, infiltration of neutrophils, fibroblasts, and macrophages, epidermal keratinocyte stratification, or collagen fiber configuration. CONCLUSIONS: Integra elicited the greatest foreign body response. Although the Dermalogen group had the thickest elastin fiber fragments, Dermagraft may have initiated the earliest elastin fiber formation in the wounds. While all dermal substitutes were incorporated into the wound bed and wound contracture was decreased, acellular dermal matrix and Alloderm, both human skin-derived products, produced less contraction and the thickest new "dermis" in the healed wounds compared to the control or synthetic dermal substitutes.