David S. Kauvar

The epidemiology and modern management of traumatic hemorrhage: US and international perspectives

Trauma is a worldwide problem, with severe and wide ranging consequences for individuals and society as a whole. Hemorrhage is a major contributor to the dilemma of traumatic injury and its care. In this article we describe the international epidemiology of traumatic injury, its causes and its consequences, and closely examine the role played by hemorrhage in producing traumatic morbidity and mortality. Emphasis is placed on defining situations in which traditional methods of hemorrhage control often fail. We then outline and discuss modern principles in the management of traumatic hemorrhage and explore developing changes in these areas. We conclude with a discussion of outcome measures for the injured patient within the context of the epidemiology of traumatic injury.

Effectiveness of Self-Applied Tourniquets in Human Volunteers

Background. Tourniquets are not commonly used in routine extremity trauma, but can be vital for hemorrhage control in austere conditions. Objective. To determine the effectiveness in human volunteers of currently available self-applied tourniquets for extremity hemorrhage. Methods. Seven tourniquets were tested on the thigh for elimination of detectable distal pulse by Doppler auscultation at the popliteal artery (experiment I, n = 18 subjects). The tourniquets that were effective in ≥80% of subjects in experiment I were tested for effectiveness on the upper arm by auscultation at the radial artery (experiment II, n = 12 subjects). Results. Three of the seven tourniquets were effective in all subjects in experiment I; a fourth tourniquet was effective in 88%. Three of the four successful devices were also 100% effective in experiment II; the fourth was effective in 75%. Failure of tourniquets to eliminate distal Doppler pulse signal was due to inadequate mechanical advantage for tightening, device failure (breakage), or intolerable pinching or circumferential pain prior to pulse elimination. The Combat Application Tourniquet (North American Rescue Products, Inc.), the Emergency & Military Tourniquet (Delfi Medical Innovations, Inc.), andthe Special Operations Forces Tactical Tourniquet (Tactical Medical Solutions, LLC) were all found to be 100% effective in elimination of distal arterial pulse in both the arm andthe leg in all subjects. Conclusion. Some commercially available tourniquets do not reliably occlude arterial blood flow andmay not be successful in preventing extremity exsanguination in a trauma patient. Potential purchasers of such devices should bear this in mind when selecting a device for clinical use.

Comparison Between Civilian Burns and Combat Burns From Operation Iraqi Freedom and Operation Enduring Freedom

Objective:To assess outcome differences between locally burned civilians and military personnel burned in a distant combat zone treated in the same facility. Summary Background Data:The United States Army Institute of Surgical Research (USAISR) Burn Center serves as a referral center for civilians and is the sole center for significant burns in military personnel. We made the hypothesis that outcomes for military personnel burned in the current conflict in Iraq and Afghanistan would be poorer because of delays to definitive treatment, other associated injury, and distance of evacuation. Methods:We reviewed the civilian and military records of patients treated at the USAISR from the outset of hostilities in Iraq in April 2003 to May 2005. Demographics, injury data, mortality, and clinical outcomes were compared. Results:We cared for 751 patients during this time period, 273 of whom were military (36%). Military injuries occurred in a younger population (41 ± 19 vs. 26 ± 7 years for civilian and military respectively, P < 0.0001) with a longer time from injury to burn center arrival (1 ± 5 days vs. 6 ± 5, P < 0.0001), a higher Injury Severity Score (ISS 5 ± 8 vs. 9 ± 11, P < 0.0001), and a higher incidence of inhalation injury (8% vs. 13%, P = 0.024). Total burn size did not differ. Mortality was 7.1% in the civilian and 3.8% in the military group (P = 0.076). When civilians outside the age range of the military cohort were excluded, civilian mortality was 5.0%, which did not differ from the military group (P = 0.57). Total body surface area (TBSA) burned, age ≥40 years, presence of inhalation injury, and ventilator days were found to be important predictors of mortality by stepwise regression, and were used in a final predictive model with the area under receiver operator characteristic curve of 0.97 for both populations considered together. No significant effect of either group was identified during development. Conclusions:Mortality does not differ between civilians evacuated locally and military personnel injured in distant austere environments treated at the same center.

The Combined Influence of Hemorrhage and Tourniquet Application on the Recovery of Muscle Function in Rats

Objective: The objective of this study was to compare the effect of tourniquet-induced ischemia/reperfusion (I/R) injury on the recovery of muscle function with and without prior hemorrhage. Methods: Male Sprague-Dawley rats (initially 400-450 g) were randomly assigned to 1 of 4 groups (n = 8 per group): (1) hemorrhage (33% of estimated blood volume) plus tourniquet +H/+TK; (2) tourniquet alone (−H/+TK); (3) hemorrhage alone (+H/−TK); and (4) surgical control (−H/−TK). A pneumatic tourniquet was applied to the upper leg for 4 hours, followed by 2 weeks of recovery. For +H animals, tourniquets were applied at the conclusion of blood withdrawal. The predominantly fast-twitch plantaris and the predominantly slow-twitch soleus muscles were examined using in situ isometric muscle function 2 weeks following treatment. Results: Tourniquet application resulted in significantly greater loss of force production [peak tetanic force (Po)] in the plantaris compared with the soleus. The decrease in Po was a result of both a loss of muscle mass and a reduction in specific force [force per unit weight; Po (n/g)]. Hemorrhage prior to tourniquet application significantly increased the extent of functional loss compared with tourniquet alone in the plantaris but not the soleus. Hemorrhage prior to tourniquet application significantly reduced the rate of postsurgical recovery of body weight. Conclusion: The functional loss resulting from tourniquet application is exacerbated by the superimposition of hemorrhage in the predominantly fast-twitch plantaris but not the predominantly slow-twitch soleus. This was likely a result of metabolic derangement resulting from the combination of hemorrhage and tourniquet application. The development of interventions designed to attenuate the loss of muscle mass and function following complex trauma is necessary for optimal patient recovery.

Effect of Reactive Skin Decontamination Lotion on Skin Wound Healing in Laboratory Rats

Reactive skin decontamination lotion (RSDL) is a proposed replacement for the existing skin and equipment decontamination kit. Because RSDL may need to be used to decontaminate wounded personnel, we conducted an assessment of the effect of this agent on wound healing. A skin incision model using male Sprague Dawley rats (n = 19 rats/group) was used. A 7.0-cm incision was made through the skin, and RSDL was (experimental group) or was not (control group) applied to the open wound; the wound edges were then approximated with sutures. Seven days later, animals were euthanized and wound samples were taken. Healing was assessed by measuring mechanical strength, collagen content, and histological appearance. RSDL-treated wounds had 23% lower tensile strength (p < 0.05) and 11% lower collagen content (p < 0.05) than did the untreated control wounds. Histological assessments did not differ significantly between groups. The results of this investigation demonstrate that the application of RSDL directly to an open wound impairs wound strength and decreases collagen content in the early phases of wound healing. This may have clinical implications for the treatment and outcomes of chemical casualty combat trauma.

Burn Hazards of the Deployed Environment in Wartime: Epidemiology of Noncombat Burns from Ongoing United States Military Operations

BACKGROUND Service in the deployed military environment carries risks for accidental (noncombat-related) burns. Examining these risks can assist in the development of military burn prevention measures. This study endeavored to examine noncombat burn epidemiology in the context of similar civilian data. STUDY DESIGN We performed a retrospective cohort study of consecutive casualties evacuated from operational military theaters in Iraq and Afghanistan to the sole tertiary military burn center in the US. Military data were compared with database samples of the US population from the American Burn Association and the Centers for Disease Control and Prevention. RESULTS The main causes of the 180 noncombat burns seen from March 2003 to June 2008 were waste burning, fuel mishaps, and unintentional ordinance detonations. Overall prevalence of noncombat burns was 19.5 burns/100,000 person-years lived. If causes specific to military operations are removed, military prevalence was 13.0/100,000. More than one-third of noncombat burns occurred in the first year of the study; a period of stability followed. A similar US population had an accidental burn prevalence of 7.1/100,000 from 2003 to 2007. Burn size, presence of inhalation injury, and burn center mortality were not different from those in a similar civilian cohort. CONCLUSIONS Deployed service members have a greater risk of unintentional burns than a similar civilian cohort does. This is in part because of the specific dangers of military activities. More attention to deployed military burn prevention is needed, especially early in combat support operations.

Endovascular versus open management of blunt traumatic aortic disruption at two military trauma centers: comparison of in-hospital variables.

BACKGROUND Blunt traumatic aortic disruption (BTAD) carries significant mortality and morbidity. Traditional open repair has appreciable risks of perioperative mortality and spinal cord ischemic complications. Endovascular repair may reduce the incidence of these adverse outcomes. We present the experience at two military trauma centers with thoracic aortic endografting for trauma (TAET) and compare this with recent open experience. METHODS A review of inpatient records was performed. All patients undergoing open repair or TAET for acute BTAD were studied. Collected data included demographics, injury characteristics, and in-hospital variables. Descriptive statistics were calculated with two-tailed t-tests performed for comparison of continuous variables. RESULTS Five open and eight TAET repairs were performed. Mean age was 32 years (range 28-50) in the TAET group and 35 (25-57) in the open group. All patients, except one TAET, had at least one associated injury with thoracic injuries predominating. Twelve BTAD were just distal to the left subclavian artery. One injury, treated with TAET, was just proximal to the celiac. Operative blood loss averaged 298 +/- 394 mL in the TAET group vs. 2,400 +/- 3,800 mL in the open group (p = 0.18). Crystalloid infusions were similarly reduced in TAET patients, 1,019 +/- 532 mL vs. 4,860 +/- 1,547 mL, p < 0.05), as were red blood cell transfusions, 1.6 units vs. 5.0 units (p = 0.12). The majority of patients [6/8 (75%) TAET, 5/5 (100%) open] experienced an inpatient complication (p = 0.09). All open patients had at least one infectious complication. There were no inpatient deaths related to aortic injury or spinal cord ischemic complications. CONCLUSIONS TAET is feasible for the treatment of BTAD in military trauma centers. It is important for military centers to accomplish this with adequate results as endovascular technologies are now being taken to the battlefield. Decreased blood loss and resuscitation requirements compared to open repair are likely contributors to improved outcomes with TAET.