Print this pageImproved Long-Term Outcomes Following Temporary Vascular Shunting for Wartime Vascular Injury: A Case Control Analysis from the GWOT Vascular Initiative
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Shaun M. Gifford*1, Gilbert Aidinian*2, W. Darrin Clouse1, Charles J. Fox*2, W. Tracey Jones*1, Brandon W. Propper*1, Gabriel E. Burkhardt*1, Todd E. Rasmussen*1
1Wilford Hall Medical Center, San Antonio, TX;2Walter Reed Army Medical Center, Washington, DC, DC
Background: Extremity vascular injury remains a leading cause of morbidity and mortality on the battlefield. Experience in Iraq and Afghanistan demonstrates that 75% of battle-related injuries occur in the extremities and the rate of vascular injury is now 3-5 times reported in previous wars. The management of this injury pattern has evolved over the past century from ligation in World Wars I and II, to vascular reconstruction first initiated in Korea and then extended in Vietnam and now the Global War on Terrorism (GWOT). Amputation rates associated with extremity vascular injury have decreased with each wartime experience from 50% in World Wars I and II to 10-20% in Korea and Vietnam. To date, early amputation rates associated with extremity vascular injury reported from GWOT are between 5-10%.
Modern advances in the management of vascular injury include positioning of forward surgical teams (FSTs) close to the location of wounding, use of adjuncts such as commercially designed tourniquets and temporary vascular shunts (TVS), and a theater-wide trauma system and registry. Level II FSTs allow initiation of the triad of vascular injury exploration, restoration of flow and fasciotomy most often within 60 minutes of wounding. Tourniquets have been useful in this conflict because of their unique design and their early evaluation and removal by surgical teams also within 60 minutes of application. TVS used to restore extremity perfusion in the setting of vascular injury have been shown to be commonly used during times of high casualty flow. This adjunct has been particularly useful in larger or proximal vascular injuries including extremity venous injuries. The Joint Theater Trauma System (JTTS) and Registry (JTTR) promote the most efficient placement of surgical resources, maximize casualty movement, and provide treatment information across all echelons of care in both theaters of war. GWOT represents the first sustained military conflict in which the impact of these advances, collective and individual, can be assessed on a large scale with meaningful outcomes data.
Despite encouraging experiences with the management of vascular injury from both Level III in-theater hospitals (Air Force Theater Hospital, Balad Air Base, Iraq) and Level V facilities in the US (Walter Reed Army Hospital, Washington, DC) none have provided outcomes data relating to amputation free survival. Similarly in-theater descriptions of TVS allude only to technical considerations and immediate limb salvage and fail to address any long-term positive or negative effect of this surgical adjunct on outcomes. The objective of this study is to harness the power of individual vascular registries and the JTTR to provide meaningful limb salvage outcomes data for wartime extremity vascular injury. An additional aim of this analysis is to assess for any positive or negative impact of TVS on limb salvage following vascular injury.
Methods: The Balad, Iraq and Walter Reed Vascular Registries were retrospectively reviewed for cases in which TVS were used in the management of extremity vascular injury prior to definitive repair. Cases were researched using the JTTR located at the Institute of Surgical Research, Fort Sam Houston, Texas. Additional information was obtained from the Armed Forces electronic medical record system, and via direct patient contact. All data were obtained under a human use protocol with Institutional Review Board approval through the Department of Clinical Investigation at Brooke Army Medical Center, Fort Sam Houston, Texas.
Dates of injury were June 2003 through December 2007 and patients identified with extremity vascular injury in which temporary vascular shunting was used comprise the study or TVS Group. These cases were matched to a cohort of patients, or Control Group, injured during the same time period having sustained extremity vascular injury managed without TVS. The TVS and Control Groups were also matched for distribution of injury (upper and lower extremity). The TVS and Control Groups were reviewed for demographics, en route care, vascular injury repair method, complications, and follow-up information including limb salvage. Iraqi national and non-US coalition forces were excluded due to the inability to obtain follow-up information. Descriptive statistics were employed and means were compared using a Student t-test. Kaplan-Meier with log-rank test and Cox proportional-hazards regression were used to define amputation-free survival and to describe the impact of TVS on limb salvage.
Results: Temporary vascular shunt utilization data was obtained for 64 arterial injuries in 62 injured US Troops from June 2003 until December 2007. Of these injuries, 25 (39%) had concomitant venous injury, 13 employing venous TVS. The Control Group consisted of 61 arterial injuries in 60 injured US Troops, with a concomitant venous injury rate of 38% (N=23). Distribution of injury site and age at time of injury was similar between the TVS and Control Groups (Table 1). Army and Marine casualties predominated, making up 60% and 39% in the TVS Group and 75% and 20% in the Control Group, respectively. 97% of the casualties occurred in the Iraqi theater with the remaining injuries occurring in Afghanistan. Demographics and treatment for the two cohorts are described in Table 1.
| TVS Group (n=64) | Control Group (n=61) | P value | |
| Age | 25 (SD 7.2) | 27 (SD 7) | P = 0.21 |
| Injury distribution | Upper extremity 30% (n=19) Lower extremity 70% (n=45) |
Upper extremity 26% (n=16) Lower extremity 74% (n=45) |
P =0.45 P = 0.41 |
| Follow-up (months) | 22 (range=1 to 44) | 23 (range=3 to 54) | P = 0.69 |
| Tourniquet | 51% (n=33) | 38% (n=23) | P =0.09 |
| Treatment at Level II | 27% (n=17) | 10% (n=6) | P=0.01 |
| Fasciotomy | 65% (n=42) | 64% (n=39) | P = 0.46 |
| MESS | 6 (SD 1.8) | 5 (SD 1.6) | P = 0.14 |
| ISS_05 | 16 (SD 6.5) | 15 (SD 8.6) | P = 0.57 |
Table 1: Demographics and treatment
Descriptive indices demonstrated no difference between groups in most major categories although patients in the TVS Group were nearly three times as likely to have been treated initially at a Level II surgical facility (Table 1). The 2005 Injury Severity Score (ISS_05) was 16 (SD 6.5, Range 4-35) and 15 (SD 8.6, Range 2-43) for the TVS and Control Groups, respectively (P=0.57). Similarly, the Mangled Extremity Severity Score (MESS) was not significantly different between the TVS and Control Groups (6, SD 1.8 and 5, SD 1.6; P=0.14). Cox regression demonstrated that MESS scores dichotomized to 8 and above were at increased risk of extremity amputation (hazard ratio = 10; 95% [CI] 4.3 to 23.9; P<0.001) compared to MESS scores ranging 1-7. High energy munitions led to several patients in each cohort having multiple injuries (Table 2). Torso injury, which included abdominal and thoracic injuries, was significantly more prevalent in the TVS Group versus Control Group.
| Associated Injury | TVS Group (n=64) | Control Group (n=61) | P value |
| Nerve | 23% (n=15) | 33% (n=20) | P = 0.17 |
| Bone | 57% (n=37) | 59% (n=36) | P = 0.48 |
| Torso | 46% (n=28) | 17% (n=10) | P = .0006 |
| Head | 10% (n=6) | 18 % (n=11) | P = 0.14 |
Table 2: Associated injuries
In the short term, more primary amputations were performed in the Control Group than the TVS Group (13% (n=8) and 3% (n=2); P=0.044). At two years follow-up, limb salvage rates were 83% in the TVS group and 77% in the control group. Kaplan-Meier analysis (Figure 1) demonstrated amputation free survival of 82% and 77% at 1600 days in the TVS and Control Groups respectively (p=0.42).
Figure 1: Kaplan-Meier analysis of limb salvage
After adjustment for MESS score, the TVS group had a significantly reduced hazard of amputation (HR=0.43; 95% [CI] 0.19 to 0.96; P=0.04) (Figure 2).
Figure 2. Cox regression analysis adjusted for MESS
Conclusions: This study provides the first meaningful outcomes data following extremity vascular injury in wartime. Although long-term limb salvage rates are excellent, they are not as high as those reported in the early postoperative period indicating a subset of patients receiving amputation during the rehabilitation period. These results provide a more realistic limb salvage rate using a novel theater-wide trauma system and registry and outcomes analysis. Temporary vascular shunts used as a damage control adjunct in the setting of extremity vascular injury have no negative impact on long-term limb salvage. On the contrary, the use of TVS in the most seriously injured of extremities is associated with lower rates of amputation. The impact of TVS and other modern combat casualty care advances on quality or functional limb salvage remain to be delineated.
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