Incidence of primary blast injury in US military overseas contingency operations: a retrospective study.

OBJECTIVES: The present retrospective study was performed to determine the incidence and outcome of primary blast injury and to identify possible changes over the course of the conflicts between 2003 and 2006. SUMMARY BACKGROUND DATA: Combat physicians treating patients injured in overseas contingency operations observed an increase in the severity of explosion injuries occurring during this period. METHODS: This retrospective study included service members injured in explosions between March 2003 and October 2006. The Joint Theater Trauma Registry provided demographic information, injury severity score, and International Classification of Diseases 9 codes used to diagnose primary blast injury. Autopsy reports of the last 497 combat-related deaths of 2006 were also reviewed. RESULTS: Of 9693 admissions, of which 6687 were injured in combat, 4765 (49%) were injured by explosions: 2588 in 2003-2004 and 1935 in 2005-2006. Dates of injury were unavailable for 242 casualties. Injury severity score (9 +/- 10 vs. 11 +/- 10, P < 0.0001) and incidence of primary blast injury (12% vs. 15%, P < 0.01) increased. The return-to-duty rate decreased (40% vs. 18%, P < 0.001), but mortality remained low (1.4% vs. 1.5%, P = NS). There was no significant difference in incidence of primary blast injury between personnel who were killed in action and those who died of wounds at a medical facility. CONCLUSIONS: Injury severity and incidence of primary blast injury increased during the 4-year period, whereas return-to-duty rates decreased. Despite increasingly devastating injuries, the mortality rate due to explosion injuries remained low and unchanged.

The effect of a hypobaric, hypoxic environment on acute skeletal muscle edema after ischemia-reperfusion injury in rats.

BACKGROUND: Clinicians have postulated that decreased atmospheric pressure during air evacuation exacerbates muscle edema and necrosis in injured limbs. The present study investigated whether the mild hypobaric, hypoxic conditions of simulated flight during muscle reperfusion worsened muscle edema and muscle injury in an established animal model. METHODS: Twenty male Sprague-Dawley rats underwent tourniquet-induced hind limb ischemia for 2h. After removal of the tourniquet, rats were divided into two groups (n=10/group), and exposed to either (1) hypobaric, hypoxic conditions (HB) of 522 mm Hg (simulating 10,000 feet, the upper limit of normal aircraft cabin pressure), or (2) normobaric, normoxic conditions (NB) of 760 mm Hg (sea level), for 6h. Muscle wet weight, muscle dry:wet weight ratios, viability, and routine histology were measured on the gastrocnemius and tibialis anterior muscles. Blood samples were analyzed for percentage hematocrit, leukocyte count, and coagulation status. RESULTS: Ischemia resulted in significant edema in both groups (P<0.05). Normobaric normoxia caused greater edema in the gastrocnemius compared with hypobaric hypoxia; the tibialis anterior was not significantly different between groups. The decrease in body weight for NB and HB was 3.4+/-1.4 and 10.7+/-1.2g, respectively (P<0.05). Hematocrit was 44.7+/-0.5 and 42.6+/-0.6 (P<0.05). CONCLUSIONS: The hypobaric, hypoxic conditions of simulated medical air evacuation were not associated with increased muscle edema following 2h of ischemic injury. This suggests that other factors, such as resuscitation, may be the cause of muscle edema in flight-evacuated patients.

Posttraumatic stress disorder in combat casualties with burns sustaining primary blast and concussive injuries.

BACKGROUND: There is a heightened focus on postexplosion functional outcomes in combat casualties. Previously, we reported a high prevalence of posttraumatic stress disorder (PTSD) (32%) and mild traumatic brain injury (mTBI) (41%) in patients with explosion-related burns. We hypothesized that the prevalence of PTSD in patients with burn was associated with primary blast injuries (PBIs) and mTBI. METHODS: We reviewed the records of 333 patients admitted consecutively to the United States Army Institute of Surgical Research burn center for explosion-related injuries between March 2003 and March 2006. By using the Posttraumatic Checklist, Military Version (PCL-M), patients were evaluated for PTSD symptoms (PCL-M score >or=44). Loss of consciousness defined mTBI. Patient data were analyzed in groups based on PTSD (yes or no), mechanism of injury (improvised explosive device [IED] vs. other explosive), PBI (yes or no), and mTBI (yes or no). RESULTS: Of 333 patients, 119 had PTSD assessments. Overall, PTSD was 22% (26 of 119). The prevalence of PTSD differed between mechanism of injury groups (p = 0.03). In the IED group (n = 105), 25% had PTSD symptoms and 18% had mTBI; patients injured by other explosive devices (n = 14) had no PTSD symptoms and one had mTBI (p = 0.04; p = 0.69, respectively). Also in the IED group, in patients with PBI, PTSD was 45% (9 of 20) compared with 20% (17 of 85) without PBI (odds ratio=3.27; 95% confidence interval, 1.17-9.16). More patients with PBI and mTBI (4 of 6; 67%) had PTSD symptoms compared with other patients (22 of 99; 22%) (odds ratio, 7.00; 95% confidence interval, 1.20-40.78). No other associations were found between PBI and mTBI. CONCLUSION: IED-wounded burn patients with PBI and mTBI have a greater prevalence of PTSD. Patients who did not have IED-related injuries did not have PTSD and only one had mTBI.

Primary blast injury: update on diagnosis and treatment.

BACKGROUND: : Injuries from combat and terrorist explosions are increasing worldwide. As such, physicians can expect to treat more patients with complex and unique patterns of injury produced not only by fragments and blunt trauma, but also by high-pressure air expanding from the detonation center. DISCUSSION: : Tissue damage from the blast wave or primary blast injury can be an important cause of occult trauma to the ocular, aural, pulmonary, cardiovascular, musculoskeletal, and neurologic systems. Awareness of the extensive corporal effects of the blast wave is an essential prerequisite to diagnosis. SUMMARY: : This article focuses on the incidence, risk factors, diagnosis, management, and screening for primary blast injury.

Complications after fasciotomy revision and delayed compartment release in combat patients.

BACKGROUND: Incomplete or delayed fasciotomies are associated with muscle necrosis and death in civilian trauma. Combat explosions severely damage tissue and distort normal anatomy making fasciotomies challenging. Rapid air evacuation may delay treatment of patients with evolving extremity compartment syndrome. We investigated the impact of fasciotomy revision and delayed compartment release on combat casualties after air evacuation. METHODS: A retrospective review was performed of combat casualties who underwent fasciotomies in Iraq, Afghanistan, or at Landstuhl Regional Medical Center between January 1, 2005 and August 31, 2006. Outcomes were rates of muscle excision, major amputation, and mortality. RESULTS: A total of 336 patients underwent 643 fasciotomies. Most were to the lower leg (49%) and forearm (23%). Patients who underwent a fasciotomy revision had higher rates of muscle excision (35% vs. 9%, p < 0.01) and mortality (20% vs. 6%, p < 0.01) than those who did not receive a revision. The anterior and deep compartments of the lower leg were the most commonly unopened. Patients who underwent fasciotomy after evacuation had higher rates of muscle excision (25% vs. 11%), amputation (31 vs. 15%), and mortality (19% vs. 5%) than patients who received their fasciotomies in the combat theater (p < 0.01). Patients who underwent revisions or delayed fasciotomies had higher Injury Severity Score and larger burns as well as lower systolic blood pressure, acidosis, and more pressor use during air evacuation. These patients also received more blood products at Landstuhl Regional Medical Center. CONCLUSION: Fasciotomy revision was associated with a fourfold increase in mortality. The most common revision procedures were extension of fascial incisions and opening new compartments. The most commonly unopened compartment was the anterior compartment of the lower leg. Patients who underwent delayed fasciotomies had twice the rate of major amputation and a threefold higher mortality.

Tympanic membrane perforation and hearing loss from blast overpressure in Operation Enduring Freedom and Operation Iraqi Freedom wounded.

BACKGROUND: Tympanic membrane perforation is the most common primary blast injury in the current conflicts and occurs in approximately one tenth of service members wounded by combat explosions. We wanted to determine the severity of perforation and its effect on hearing and combat readiness. METHODS: This analysis is a retrospective study of US service members injured in combat explosions in Afghanistan or Iraq and treated at our institution between March 2003 and July 2006. Data captured included location and grade of perforation, symptoms, healing rates, audiogram results, need for hearing aids, and loss of eligibility for military service. RESULTS: Of 436 explosion-wounded patients admitted to our facility, 65 (15%) patients had tympanic membrane perforation diagnosed by the otolaryngology service. A total of 97 tympanic membrane perforations occurred among 65 patients. The average surface area involved was 41% +/- 32% (right) and 35% +/- 34% (left). More than one third of perforations were grade 4. The most common locations were central and anterior-inferior. Most (83%) patients reported symptoms, most commonly diminished hearing (77%) and tinnitus (50%). Outcome data were available for 77% of perforations. Spontaneous healing occurred in 48%. The remainder (52%) had surgical intervention. The most common audiogram abnormality was mild high frequency hearing loss. Ultimately, three patients (5%) required hearing aids and one discharge from military service. CONCLUSIONS: Tympanic membrane perforation occurs in 16% of explosion-injured patients. Most patients are symptomatic and many have large perforations requiring operative intervention. Long-term hearing loss is uncommon but does impact ability to continue military service.

Injury severity and causes of death from Operation Iraqi Freedom and Operation Enduring Freedom: 2003-2004 versus 2006.

BACKGROUND: The opinion that injuries sustained in Iraq and Afghanistan have increased in severity is widely held by clinicians who have deployed multiple times. To continuously improve combat casualty care, the Department of Defense has enacted numerous evidence-based policies and clinical practice guidelines. We hypothesized that the severity of wounds has increased over time. Furthermore, we examined cause of death looking for opportunities of improvement for research and training. METHODS: Autopsies of the earliest combat deaths from Iraq and Afghanistan and the latest deaths of 2006 were analyzed to assess changes in injury severity and causes of death. Fatalities were classified as nonsurvivable (NS) or potentially survivable (PS). PS deaths were then reviewed in depth to analyze mechanism and cause. RESULTS: There were 486 cases from March 2003 to April 2004 (group 1) and 496 from June 2006 to December 2006 (group 2) that met inclusion criteria. Of the PS fatalities (group 1: 93 and group 2: 139), the injury severity score was lower in the first group (27 +/- 14 vs. 37 +/- 16, p < 0.001), and had a lower number of abbreviated injury scores >or=4 (1.1 +/- 0.79 vs. 1.5 +/- 0.83 per person, p < 0.001). The main cause of death in the PS fatalities was truncal hemorrhage (51% vs. 49%, p = NS). Deaths per month between groups doubled (35 vs. 71), whereas the case fatality rates between the two time periods were equivalent (11.0 vs. 9.8, p = NS). DISCUSSION: In the time periods of the war studied, deaths per month has doubled, with increases in both injury severity and number of wounds per casualty. Truncal hemorrhage is the leading cause of potentially survivable deaths. Arguably, the success of the medical improvements during this war has served to maintain the lowest case fatality rate on record.

Lightning injury: a review.

Lightning is an uncommon but potentially devastating cause of injury in patients presenting to burn centers. These injuries feature unusual symptoms, high mortality, and significant long-term morbidity. This paper will review the epidemiology, physics, clinical presentation, management principles, and prevention of lightning injuries.

Compartment syndrome performance improvement project is associated with increased combat casualty survival.

BACKGROUND: In 2008, we showed that incomplete or delayed extremity fasciotomies were associated with mortality and muscle necrosis in war casualties with limb injury. Subsequently, we developed an education program focused on surgeon knowledge gaps regarding the diagnosis of compartment syndrome and prophylactic fasciotomy. The program included educational alerts, classroom training, video instruction, and a research publication. We compared casualty data before and after the program implementation to determine whether the education altered outcomes. METHODS: Similar to the previous study, a case series was made from combat casualty medical records. Casualties were US military servicemen with fasciotomies performed in Iraq, Afghanistan, or Germany between two periods (periods 1 and 2). RESULTS: In both periods, casualty demographics were similar. Most fasciotomies were performed to the lower leg and forearm. Period 1 had 336 casualties with 643 fasciotomies, whereas Period 2 had 268 casualties with 1,221 fasciotomies (1.9 vs. 4.6 fasciotomies per casualty, respectively; p < 0.0001). The mortality rate decreased in Period 2 (3%, 8 of 268 casualties) from Period 1 (8%, 26 of 336 casualties; p = 0.0125). Muscle excision and major amputation rates were similar in both periods (p > 0.05). Rates of casualties with revision fasciotomy decreased to 8% in Period 2, (22 of 268 casualties) versus 15% in Period 1 (51 of 336 casualties; p = 0.009). CONCLUSION: Combat casualty care following implementation of a fasciotomy education program was associated with improved survival, higher fasciotomy rates, and fewer revisions. Because delayed fasciotomy rates were unchanged, further effort to educate providers may be indicated. LEVEL OF EVIDENCE: Therapeutic study, level IV.

Burn center treatment of patients with severe anhydrous ammonia injury: case reports and literature review.

Anhydrous ammonia, a widespread industrial chemical, can cause severe inhalation and ophthalmic injuries, as well as cutaneous burns. We present five patients with ammonia injury treated at our burn center after an explosion in a warehouse. The challenges inherent in managing the pulmonary complications of this injury are emphasized.