Extremity Hemorrhage Control Research Articles

Immediate Medical Care Rendered by U.S. Law Enforcement Officers After Officer-Involved Shootings – An Open-Access Public Domain Video Analysis

Introduction:After officer-involved shootings, rapid delivery of emergency medical care is critical but may be delayed due to scene safety concerns. The purpose of this study was to describe medical care rendered by law enforcement officers (LEO) after lethal force incidents.Method:Retrospective analysis of open-source video footage of officer-involved shootings (OIS) occurring between 2/15/2013 and 12/31/2020. Frequency and nature of care provided, time until LEO and emergency medical services (EMS) care, and mortality outcomes were evaluated. The study was deemed exempt by the Mayo Clinic Institutional Review Board.Results:342 videos were included in the final analysis. LEOs rendered care in 172 (50.3%) incidents. The average elapsed time from the time of injury to LEO-provided care was 155.8 + 198.8 seconds. Hemorrhage control was the most common intervention performed. An average of 214.2 seconds elapsed between LEO care and EMS arrival. No mortality difference was identified between LEO vs EMS care (p = 0.1631). Subjects with truncal wounds were more likely to die than those with extremity wounds (p < 0.00001).Conclusion:LEO rendered medical care in half of all OIS incidents, initiating care on average 3.5 minutes prior to EMS arrival. Although no significant mortality difference was noted for LEO versus EMS care, this finding must be interpreted cautiously, as specific interventions, such as extremity hemorrhage control, may have impacted select patients. Future studies are needed to determine optimal LEO care for these patients.

Immediate Medical Care Rendered by US Law Enforcement Officers after Officer-Involved Shootings - An Open-Access Public Domain Video Analysis.

After officer-involved shootings (OIS), rapid delivery of emergency medical care is critical but may be delayed due to scene safety concerns. The purpose of this study was to describe medical care rendered by law enforcement officers (LEOs) after lethal force incidents. Retrospective analysis of open-source video footage of OIS occurring from February 15, 2013 through December 31, 2020. Frequency and nature of care provided, time until LEO and Emergency Medical Services (EMS) care, and mortality outcomes were evaluated. The study was deemed exempt by the Mayo Clinic Institutional Review Board. Three hundred forty-two (342) videos were included in the final analysis; LEOs rendered care in 172 (50.3%) incidents. Average elapsed time from time-of-injury (TOI) to LEO-provided care was 155.8 (SD = 198.8) seconds. Hemorrhage control was the most common intervention performed. An average of 214.2 seconds elapsed between LEO care and EMS arrival. No mortality difference was identified between LEO versus EMS care (P = .1631). Subjects with truncal wounds were more likely to die than those with extremity wounds (P < .00001). It was found that LEOs rendered medical care in one-half of all OIS incidents, initiating care on average 3.5 minutes prior to EMS arrival. Although no significant mortality difference was noted for LEO versus EMS care, this finding must be interpreted cautiously, as specific interventions, such as extremity hemorrhage control, may have impacted select patients. Future studies are needed to determine optimal LEO care for these patients.

AAST multicenter prospective analysis of prehospital tourniquet use for extremity trauma.

Tourniquet use for extremity hemorrhage control has seen a recent increase in civilian usage. Previous retrospective studies demonstrated that tourniquets improve outcomes for major extremity trauma (MET). No prospective study has been conducted to date. The objective of this study was to evaluate outcomes in MET patients with prehospital tourniquet use. We hypothesized that prehospital tourniquet use in MET decreases the incidence of patients arriving to the trauma center in shock. Data were collected prospectively for adult patients with MET at 26 Level I and 3 Level II trauma centers from 2015 to 2020. Limbs with tourniquets applied in the prehospital setting were included in the tourniquet group and limbs without prehospital tourniquets were enrolled in the control group. A total of 1,392 injured limbs were enrolled with 1,130 tourniquets, including 962 prehospital tourniquets. The control group consisted of 262 limbs without prehospital tourniquets and 88 with tourniquets placed upon hospital arrival. Prehospital improvised tourniquets were placed in 42 patients. Tourniquets effectively controlled bleeding in 87.7% of limbs. Tourniquet and control groups were similarly matched for demographics, Injury Severity Score, and prehospital vital signs (p > 0.05). Despite higher limb injury severity, patients in the tourniquet group were less likely to arrive in shock compared with the control group (13.0% vs. 17.4%, p = 0.04). The incidence of limb complications was not significantly higher in the tourniquet group (p > 0.05). This study is the first prospective analysis of prehospital tourniquet use for civilian extremity trauma. Prehospital tourniquet application was associated with decreased incidence of arrival in shock without increasing limb complications. We found widespread tourniquet use, high effectiveness, and a low number of improvised tourniquets. This study provides further evidence that tourniquets are being widely and safely adopted to improve outcomes in civilians with MET. Therapeutic/Care Management; Level IV.

Evaluation of the efficacy of commercial and noncommercial tourniquets for extremity hemorrhage control in a perfused cadaver model.

Tourniquets are a critical tool in the immediate response to life-threatening extremity hemorrhage; however, the optimal tourniquet type and effectiveness of noncommercial devices remain unclear. Our aim was to evaluate the efficacy of five tourniquets in a perfused-cadaver model. This prospective study used a perfused-cadaver model with standardized superficial femoral artery injury bleeding at 700 mL/min. Five tourniquets were tested: combat application tourniquet; rapid application tourniquet system; Stretch, Wrap, And Tuck Tourniquet; an improvised triangle bandage windlass; and a leather belt. Forty-eight medical students underwent a practical hands-on demonstration of each tourniquet. Using a random number generator, they placed the tourniquets on the bleeding cadaver in random order. Time to hemostasis, time to secure devices, estimated blood loss, and difficulty rating were assessed. A one-way repeated measures analysis of variance was used to compare efficacy between the tourniquets in achieving the outcomes. The mean ± SD participant age was 25 ± 2.6 years, and 29 (60%) were male. All but one tourniquet was able to stop bleeding, but the rapid application tourniquet system had a 4% failure rate. Time to hemostasis and estimated blood loss did not differ significantly (p > 0.05). Stretch, Wrap, And Tuck Tourniquet required the longest time to be secured (47.8 ± 17.0 seconds), whereas the belt was the fastest (15.2 ± 6.5 seconds; p < 0.001). The improvised windlass was rated easiest to learn and apply, with 22 participants (46%) assigning a score of 1. Four of five tourniquets evaluated, including both noncommercial devices, effectively achieved hemostasis. A standard leather belt was the fastest to place and was able to stop the bleeding. However, it required continuous pressure to maintain hemostasis. The improvised windlass was as effective as the commercial devices and was the easiest to apply. In an emergency setting where commercial devices are not available, improvised tourniquets may be an effective bridge to definitive care.

The Efficacy of Novel Commercial Tourniquet Designs for Extremity Hemorrhage Control: Implications for Spontaneous Responder Every Day Carry.

Tourniquets (TQs) save lives. Although military-approved TQs appear more effective than improvised TQs in controlling exsanguinating extremity hemorrhage, their bulk may preclude every day carry (EDC) by civilian lay-providers, limiting availability during emergencies. The purpose of the current study was to compare the efficacy of three novel commercial TQ designs to a military-approved TQ. Nine Emergency Medicine residents evaluated four different TQ designs: Gen 7 Combat Application Tourniquet (CAT7; control), Stretch Wrap and Tuck Tourniquet (SWAT-T), Gen 2 Rapid Application Tourniquet System (RATS), and Tourni-Key (TK). Popliteal artery flow cessation was determined using a ZONARE ZS3 ultrasound. Steady state maximal generated force was measured for 30 seconds with a thin-film force sensor. Success rates for distal arterial flow cessation were 89% CAT7; 67% SWAT-T; 89% RATS; and 78% TK (H 0.89; P = .83). Mean (SD) application times were 10.4 (SD = 1.7) seconds CAT7; 23.1 (SD = 9.0) seconds SWAT-T; 11.1 (SD = 3.8) seconds RATS; and 20.0 (SD = 7.1) seconds TK (F 9.71; P <.001). Steady state maximal forces were 29.9 (SD = 1.2) N CAT7; 23.4 (SD = 0.8) N SWAT-T; 33.0 (SD = 1.3) N RATS; and 41.9 (SD = 1.3) N TK. All novel TQ systems were non-inferior to the military-approved CAT7. Mean application times were less than 30 seconds for all four designs. The size of these novel TQs may make them more conducive to lay-provider EDC, thereby increasing community resiliency and improving the response to high-threat events.

Efficacy of Novel Commercial Tourniquet Systems in Extremity Hemorrhage Control - An Ultrasound and Generated Force Study

Introduction:Tourniquets (TQ) save lives. Although military-approved TQ are more effective than improvised TQ in controlling exsanguinating extremity hemorrhage, their bulk may preclude every day carry (EDC) by civilian lay-providers.Aim:The purpose of the current study was to compare the efficacy of 3 novel commercial TQ to a military-approved TQ.Methods:A convenience sample of EM residents was utilized. Four different TQ were evaluated: Gen 7 Combat Application Tourniquet (CAT; control), Stretch Wrap and Tuck Tourniquet (SWAT-T), Gen 2 Rapid Application Tourniquet System (RATS), and Tourni-Key (TK). Popliteal artery occlusion was determined using a ZONARE ZS3 ultrasound. Steady-state maximal generated force was measured for 30 seconds with a thin-film force sensor (Singletract). Opinions were solicited at the conclusion of the study.Results:Nine residents participated in the study (7 male, 2 female). Success rates for complete arterial occlusion were 89% CAT, 67% SWAT-T, 89% RATS, and 78% TK (H 0.89, p = 0.83). Mean (± SD) times to achieve occlusion were 10.4 ± 1.7 sec CAT, 23.1 ± 9.0 sec SWAT-T, 11.1 ± 3.8 sec RATS, and 20.0 ± 7.1 sec TK (F 9.71, p &lt; 0.001). Steady-state maximal forces were 29.9 ± 1.2 N CAT, 23.4 ± 0.8 N SWAT-T, 33.0 ± 1.3 N RATS, and 41.9 ± 1.3 N TK. Participants felt that the CAT was easiest to apply (61%), followed by the RATS (33%). Participants were most likely to select the TK (44%) for EDC, followed by the RATS (33%).Discussion:In this small convenience sampling, all novel TQ systems were non-inferior to the military-approved CAT TQ. Mean application times were less than 30 seconds. The size and unique nature of these novel TQs may make them more conducive to lay-provider EDC, thereby improving the response to high threat events.

Prehospital trauma experience of the Israel defense forces on the Syrian border 2013-2017.

The Israeli Defense Force Medical Corps (IDF-MC) is routinely collecting prehospital data to establish a prehospital registry. Since February 2013, Israel has been providing medical care to Syrian refugees. This unique humanitarian aid begins in prehospital settings and typically culminates in Israeli civilian hospitals. This report describes the accumulated experience of the IDF-MC to provide Syrian refugees with prehospital treatment. Care provided by IDF-MC medical teams, including prehospital casualty care, is regularly documented and after-action reports are conducted. Records of casualties arriving at the Israeli-Syrian border from February 16, 2013, to December 31, 2017, were prospectively extracted from the IDF Trauma Registry. Patients who did not have a casualty card were excluded. The database included demographic information, injury signature and treatment given. During the study period, 2,785 Syrian casualties were treated, of whom 2,339 were trauma victims. The most common mechanism of injury was penetrating (60.4%). Prehospital lifesaving interventions included 127 endotracheal intubations, 30 cricothyroidotomies, 55 chest decompressions, and 58 tourniquets for extremity hemorrhage control. Remote Damage Control Resuscitation included reconstituted freeze-dried plasma (n = 75) and tranexamic acid (n = 222 casualties) with no adverse effects. The experience of the IDF-MC teams in caring for civilian casualties along a hostile international border is unique. In this capacity, the IDF-MC has demonstrated effectiveness in providing lifesaving and resuscitative interventions including tranexamic acid and freeze-dried plasma. In this experience, tourniquets have been effective in controlling hemorrhage when applied early and endotracheal intubation and cricothyroidotomy have provided effective airway options in select patients. Prehospital combat casualty care presents a significant challenge both in terms of providing adequate care and in terms of data collection and analysis. The experience described in this article is one example of effective, ongoing prehospital data gathering process. Efforts to provide medical relief to victims of the Syrian civil war continue to this day. While we hope for a better future, as long as these lessons continue to accumulate, it is our obligation to use them to support improvement of trauma care and hopefully save more lives. Therapeutic, level III.

Control of Traumatic Extremity Hemorrhage.

Although most extremity hemorrhage from trauma can be controlled with direct pressure and/or pressure dressings, the occasional uncontrolled hemorrhage can be life threatening. Tools that may be able to control such life-threatening extremity hemorrhage include hemostatic dressings, tourniquets, and several new devices that have recently become available. Hemostatic dressings, a relatively new concept, incorporate materials that increase coagulation into a dressing that is applied directly to the wound. Although the use of tourniquets has a long history, recent military conflicts have provided numerous studies that supported and refined their use. The novel extremity hemorrhage control devices effectively control bleeding in one of several ways: direct compression, arterial compression above the level of injury, and sealing the wounds' edges, creating a hematoma.

Prehospital use of hemostatic dressings by the Israel Defense Forces Medical Corps: A case series of 122 patients.

Hemostatic dressings are advanced topical dressings designed to control hemorrhage by enhancing clot formation. These dressings may be effective when used on injuries sustained in junctional zones. The Israeli Defense Forces Medical Corps (IDF-MC) chose to equip its medical personnel with the QuikClot Combat Gauze. There is a paucity of data describing clinical use and results of hemostatic dressing especially at the point of injury. The purpose of this article was to report the IDF-MC experience with prehospital use of the QuikClot Combat Gauze in junctional zones in a case series retrieved from the IDF Trauma Registry. All IDF Trauma Registry documented cases of prehospital use of hemostatic dressings in the IDF-MC between January 2009 and September 2014 were retrieved. Data collection included injury mechanism, wound location, reported success of hemostatic dressing, tourniquet use, lifesaving interventions, mortality, and caregiver identity. A total of 122 patients on whom 133 hemostatic dressings were applied were identified. Median age was 22 years. Of the patients, 118 (96.7%) were male and 2 (1.6%) were female (missing, n = 2). Injury mechanism was penetrating in 104 (85.2%), blunt in 4 (3.3%), and combined in 14 (11.5%) patients. Seven patients (5.9%) died. Thirty-seven dressings (27.8%) were used for junctional hemorrhage control (pelvis, shoulder, axilla, buttocks, groin, neck), and 92 dressings (72.1%) were placed in nonjunctional areas (missing, n = 4). Nonjunctional dressings included 63 (47.4%) applied to the extremities, 14 (10.5%) to the back, and 4 (3%) to the head. Hemostatic dressing application was reported as successful in 88.6% (31 of 35 available; missing, n = 2) of junctional hemorrhage applications and in 91.9% (57 of 62 available; missing, n = 1) of extremity hemorrhage applications. Hemostatic dressings seem to be an effective tool for junctional hemorrhage control and should be considered as a second-line treatment for extremity hemorrhage control at the point of injury. Therapeutic study, level V.

Tourniquet use at the Boston Marathon bombing: Lost in translation.

The Boston Marathon bombing was the first major, modern US terrorist event with multiple, severe lower extremity injuries. First responders, including trained professionals and civilian bystanders, rushed to aid the injured. The purpose of this review was to determine how severely bleeding extremity injuries were treated in the prehospital setting in the aftermath of the Boston Marathon bombing. A database was created and populated by all the Boston Level I trauma centers following the Boston Marathon bombing. Data regarding specific injuries, extremities affected, demographics, prehospital interventions (including tourniquet types), and outcomes were extracted. Of 243 injured, 152 patients presented to the emergency department within 24 hours. Of these 152 patients, there were 66 (63.6% female) experiencing at least one extremity injury, with age ranging from younger than 15 years to 71 years, and with a median Injury Severity Score (ISS) of 10 (range, 1-38). Of the 66 injured patients, 4 had upper limbs affected, 56 had injuries on the lower limbs only, and 6 had combined upper and lower limbs affected. The extremity Abbreviated Injury Scale (AIS) scores had a median of 3 (range, 1-4). There were 17 lower extremity traumatic amputations in 15 patients. In addition, there were 10 patients with 12 lower extremities experiencing major vascular injuries. Of 66 injured patients, 29 patients had recognized extremity exsanguination at the scene. In total, 27 tourniquets were applied: 16 of 17 traumatic amputations, 5 of 12 lower extremities with major vascular injuries, and 6 additional limbs with major soft tissue injury. All tourniquets were improvised, and no commercial, purpose-designed tourniquets were identified. Among all 243 patients, mortality was 0%. After the Boston Marathon bombings, extremity exsanguination at the point of injury was either left untreated or treated with an improvised tourniquet in the prehospital environment. An effective, prehospital extremity hemorrhage control posture should be translated to all civilian first responders in the United States and should mirror the military's posture toward extremity bleeding control. The prehospital response to extremity exsanguination after the Boston Marathon bombing demonstrates that our current practice is an approach, lost in translation, from the battlefield to the homeland. Epidemiologic study, level V.

Evaluation of Contingency Telemedical Support to Improve Casualty Care at a Simulated Military Intermediate Resuscitation Facility: The EM-ANGEL Study

We sought to determine whether Contingency Telemedical Support (CTS) improves the success rate and efficiency of primary care providers performing critical actions during simulated combat trauma resuscitation. Critical actions included advanced airway, chest decompression, extremity hemorrhage control, hypothermia prevention, antibiotics and analgesics, and hypotensive resuscitation, among others.Recent studies report improved survival associated with skilled triage and treatment in the out-of-hospital/preoperative phase of combat casualty care. Historically, ground combat units are assigned primary care physicians and physician assistants as medical staff, due to resource limitations. Although they are recognized as optimal resuscitators, demand for military trauma surgeons and emergency physicians exceeds supply and is unlikely to improve in the near term.A prospective trial of telemedical mentoring during a casualty resuscitation encounter was studied using a high-fidelity patient simulator (HFPS). Subjects were randomized and formed into experimental (CTS) or control teams. CTS team leaders were equipped with a headset/microphone interface and telementored by a combat-experienced emergency physician or trauma surgeon. A standardized, scripted clinical scenario and HFPS were used with 14 critical actions. At completion, subjects were surveyed. Statistical approach included contingency table analysis, two-tailed t-test, and correlation coefficient. This study was reviewed and approved by our institutional review board (IRB).Eighteen CTS teams and 16 control teams were studied. By intention-to-treat ITT analysis, 89% of CTS teams versus 56% of controls completed all life-threatening inventions (LSIs) (p<.01); 78% versus 19% completed all critical actions (p<.01); and 89% versus 56% established advanced airways within 8 minutes (p<.06). Average time to completion in minutes (95% confidence interval [CI] 95) was 12 minutes (10?14) for CTS versus 18 (16?20) for controls, with 75% of control teams not completing all critical actions.In this model, real-time telementoring of simulated trauma resuscitation was feasible and improved accuracy and efficiency of non?emergency-trained resuscitators. Clinical validation and replicated study of these findings for guiding remote damage control resuscitation are warranted.

Tourniquets, Pressure Points, and Extremity Hemorrhage

General Albert Sydney Johnston, shot from behind unintentionally by one of his own men armed with an Enfi eld rifl e, exsanguinated and died within 30 minutes from a wound to his right popliteal artery. In the general’s uniform pocket was a fi eld tourniquet. Its use could have changed world history. The battle of Shiloh, in 1862, was a Northern victory because of Johnston’s untimely loss in the afternoon of the fi rst day of the 2-day battle. 1 Fifty years later the Boy Scouts of America, still in its infancy, described the cloth and windlass tourniquet, its indication and its application with succinct clarity 2 that fl ies in the face of apparent current confusion over control of extremity hemorrhage.

Part 13: First Aid

Part 13: First Aid

Comparison of Four Hemostatic Agents versus Standard Gauze Dressing in Control of Extremity Hemorrhage in a Model of Penetrating Combat Trauma

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Comparison of 4 Hemostatic Agents, CELOX-A, ChitoFlex, WoundStat, and Combat Gauze, Versus Standard Gauze Dressing in Control of Extremity Hemorrhage in a Limited Access Swine Model of Penetrating Combat Trauma

Comparison of 4 Hemostatic Agents, CELOX-A, ChitoFlex, WoundStat, and Combat Gauze, Versus Standard Gauze Dressing in Control of Extremity Hemorrhage in a Limited Access Swine Model of Penetrating Combat Trauma

Prehospital Tourniquet Use in Operation Iraqi Freedom: Effect on Hemorrhage Control and Outcomes

Up to 9% of casualties killed in action during the Vietnam War died from exsanguination from extremity injuries. Retrospective reviews of prehospital tourniquet use in World War II and by the Israeli Defense Forces revealed improvements in extremity hemorrhage control and very few adverse limb outcomes when tourniquet times are less than 6 hours. We hypothesized that prehospital tourniquet use decreased hemorrhage from extremity injuries and saved lives, and was not associated with a substantial increase in adverse limb outcomes. This was an institutional review board-approved, retrospective review of the 31st combat support hospital for 1 year during Operation Iraqi Freedom. Inclusion criteria were any patient with a traumatic amputation, major extremity vascular injury, or documented prehospital tourniquet. Among 3,444 total admissions, 165 patients met inclusion criteria. Sixty-seven patients had prehospital tourniquets (TK); 98 patients had severe extremity injuries but no prehospital tourniquet (No TK). Extremity Acute Injury Scores were the same (3.5 TK vs. 3.4 No TK) in both groups. Differences (p < 0.05) were noted in the numbers of patients with arm injuries (16.2% TK vs. 30.6% No TK), injuries requiring vascular reconstruction (29.9% TK vs. 52.5% No TK), traumatic amputations (41.8% TK vs. 26.3% No TK), and in those patients with adequate bleeding control on arrival (83% TK vs. 60% No TK). Secondary amputation rates (4 (6.0%) TK vs. 9 (9.1%) No TK); and mortality (3 (4.4%) TK vs. 4 (4.1%) No TK) did not differ. Tourniquet use was not deemed responsible for subsequent amputation in severely mangled extremities. Analysis revealed that four of seven deaths were potentially preventable with functional prehospital tourniquet placement. Prehospital tourniquet use was associated with improved hemorrhage control, particularly in the worse injured (Injury Severity Score >15) subset of patients. Fifty-seven percent of the deaths might have been prevented by earlier tourniquet use. There were no early adverse outcomes related to tourniquet use.

Extremity War Injuries: Development of Clinical Treatment Principles

The AAOS/OTA Extremity War Injuries: Development of Clinical Treatment Principles symposium, held in January 2007, was a follow-up to the first Extremity War Injuries symposium held a year earlier. Discussion focused on four specific areas: prehospital management of extremity wounds, initial débridement, early stabilization, and postoperative wound management during air evacuation. Liberal emergency use of field tourniquets likely is contributing to lower overall mortality and is associated with very low rates of complications. Additional tools for extremity hemorrhage control, such as chitosan-based patches and granular zeolite hemostat, were postulated to be effective. Consensus opinion was that necrotic, devitalized, and contaminated tissue must be removed although objective assessment of completeness of initial débridement is difficult. Definitive open reduction and internal fixation for US and Coalition forces in the theater of operations should be limited to fracture patterns associated with significant perceived risk of delay in treatment. Finally, primary skin closure should be avoided in theater. In addition, because of the time and complications involved in transporting patients to level 4 care facilities, surgeons should consider release of compartments prior to patient transport whenever significant perceived potential for compartment syndrome is present.

Influence of Systemic Hypotension on Skeletal Muscle Ischemia-Reperfusion Injury After 4-Hour Tourniquet Application

Tourniquet use for extremity hemorrhage control is common in military trauma. Tourniquet use may be accompanied by systemic hypotension, but this phenomenon has not been studied. We aimed to define the muscle effects of the combined insult of tourniquet-induced skeletal muscle ischemia-reperfusion injury (I-R) and hemorrhagic hypotension. After a 33% carotid arterial hemorrhage, Sprague-Dawley rats underwent 240-min hindlimb ischemia induced by pneumatic tourniquet. Control animals were not hemorrhaged. No resuscitation was given. After tourniquet release, muscles were reperfused for 120 min and then dissected. Weights and mitochondrial viability assays (nitroblue tetrazolium method) were performed on the plantaris (PL), and soleus (SO). Histologic analysis was performed on the PL and SO. Muscle edema is expressed as the ratio of tourniquet limb to contralateral limb muscle weight. Animal laboratories of the United States Army Institute of Surgical Research. STUDY ANIMALS: Twelve Sprague-Dawley rats. The mean arterial pressure of hemorrhaged animals was 38 +/- 3 mm Hg before tourniquet placement and 86 +/- 4 mm Hg before release, both significantly (p < 0.05) lower than controls at the same time points. Pre- tourniquet mortality was 38% with hemorrhage and 0% without. All muscles experienced edema, with weight ratios greater than 1. The PL experienced significantly (p < 0.05) less edema with hemorrhage. Viability was unaffected by hemorrhage in all muscles, as was tissue inflammation. No differences in inflammation were observed with hemorrhage. Systemic hypotension modulates the impact of 4 hours of tourniquet ischemia by decreasing muscle edema but minimally altering measures of muscle viability. Compartment anatomy and muscle fiber type both influence muscle response to the combined insult of hypotension and I-R. In this model, hypotension did not worsen the skeletal muscle I-R observed after the use of a tourniquet for 4 hours.