Mitchell W. Cox

Penetrating femoropopliteal injury during modern warfare: Experience of the Balad Vascular Registry

OBJECTIVE Wounding patterns, methods of repair, and outcomes from femoropopliteal injury have been documented in recent civilian literature. In Operation Iraqi Freedom, as in past conflicts, these injuries continue to be a therapeutic challenge. Therefore, the objective of the current study is to document the pattern of femoropopliteal injuries, methods of repair, and early outcomes during the current military campaign in Iraq. METHODS From September 1, 2004, to April 30, 2007, all vascular injuries arriving at the Air Force Theater Hospital (the central echelon III medical facility in Iraq; equivalent to a civilian level I trauma center), Balad Air Base, Iraq were prospectively entered into a registry. From this, injuries involving the lower extremities were reviewed. RESULTS During the 32-month study period, 9289 battle-related casualties were assessed. Of these, 488 (5.3%) were diagnosed with 513 vascular injuries, and 142 casualties sustained 145 injuries in the femoropopliteal domain. Femoral level injury was present in 100, and popliteal level injury occurred in 45. Injuries consisted of 59 isolated arterial, 11 isolated venous, and 75 combined. Fifty-eight casualties were evacuated from forward locations. Temporary arterial shunts were placed in 43, of which 40 (93%) were patent on arrival at our facility. Our group used shunts for early reperfusion before orthopedic fixation, during mass casualty care, or autogenous vein harvest in 11 cases. Arterial repair was accomplished with autogenous vein in 118 (88%), primary means in nine (7%), or ligation in seven (5%). Venous injury was repaired in 62 (72%). Associated fracture was present in 55 (38%), and nerve injury was noted in 19 (13%). Early limb loss due to femoropopliteal penetrating injury occurred in 10 (6.9%). Early mortality was 3.5% (n = 5). CONCLUSIONS Femoropopliteal vascular injury remains a significant reality in modern warfare. Femoral injuries appear more prevalent than those in the popliteal region. Early results of in-theater repair are comparable with contemporary civilian reports and are improved from the Vietnam era. Rapid evacuation and damage control maneuvers such as temporary shunting and early fasciotomy assist timely definitive repair and appear effective.

Development and implementation of endovascular capabilities in wartime.

BACKGROUND Endovascular techniques are widespread in the management of civilian trauma and provide standard treatment for select injuries. Despite the commonality of this less invasive technology, there have been no reports on its use in wartime. The objective of this study was to describe the implementation of endovascular capability at a level III surgical facility in Iraq and illustrate the effectiveness of catheter-based techniques. METHODS From September 1, 2004 through April 30, 2007, injuries at the Air Force Theater Hospital, Balad, Iraq, were registered in a database and reviewed. Patients in whom endovascular procedures were performed comprise the study group (N = 139). RESULTS During this period, 150 catheter-based procedures were performed, including placement of 39 vena cava filters. The 111 nonfilter procedures were performed in the setting of extremity (N = 72), cervical (N = 19), and torso (N = 20) injuries. Of the diagnostic procedures, an abnormal finding was present in 67 (61%) cases, and 47 of these underwent either open surgical repair (N = 30) or endovascular treatment (N = 17). Endovascular therapies fell into three categories: embolization (N = 10), covered stent placement (N = 5), or miscellaneous (N = 2). The technical success rate of endovascular treatments was 100%, and procedure-related complications were uncommon (N = 4; 3%). CONCLUSION This report is the first to demonstrate the effectiveness of diagnostic and therapeutic endovascular capability in the management of acute wartime injury. Implementation of this capability has unique requirements related to imaging and a trauma-specific endovascular inventory. Once established, however, endovascular capability markedly expands the injury management armamentarium and, in certain cases, provides the preferred treatment.

Outcome-based anatomic criteria for defining the hostile aortic neck

OBJECTIVE There is abundant evidence linking hostile proximal aortic neck anatomy to poor outcome after endovascular aortic aneurysm repair (EVAR), yet the definition of hostile anatomy varies from study to study. This current analysis was undertaken to identify anatomic criteria that are most predictive of success or failure at the aortic neck after EVAR. METHODS The study group comprised 221 patients in the Aneurysm Treatment using the Heli-FX Aortic Securement System Global Registry (ANCHOR) clinical trial, a population enriched with patients with challenging aortic neck anatomy and failure of sealing. Imaging protocols were not protocol specified but were performed according to the institutions standard of care. Core laboratory analysis assessed the three-dimensional centerline-reformatted computed tomography scans. Failure at the aortic neck was defined by type Ia endoleak occurring at the time of the initial endograft implantation or during follow-up. Receiver operating characteristic curve analysis was used to assess the value of each anatomic measure in the classification of aortic neck success and failure and to identify optimal thresholds of discrimination. Binary logistic regression was performed after excluding highly intercorrelated variables, creating a final model with significant predictors of outcome after EVAR. RESULTS Among the 221 patients, 121 (54.8%) remained free of type Ia endoleak and 100 (45.2%) did not. Type Ia endoleaks presented immediately after endograft deployment in 58 (58.0%) or during follow-up in 42 (42.0%). Receiver operating characteristic curve analysis identified 12 variables where the classification of patients with type Ia endoleak was significantly more accurate than chance alone. Increased aortic neck diameter at the lowest renal artery (P = .013) and at 5 mm (P = .008), 10 mm (P = .008), and 15 mm (P = .010) distally; aneurysm sac diameter (P = .001), common iliac artery diameters (right, P = .012; left, P = .032), and a conical (P = .049) neck configuration were predictive of endoleak. By contrast, increased aortic neck length (P = .050), a funnel-shaped aortic neck (P = .036), and neck mural thrombus content, as measured by average thickness (P = .044) or degrees of circumferential coverage (P = .029), were protective against endoleak. Binary logistic regression identified three variables independently predictive of type Ia endoleak. Neck diameter at the lowest renal artery (P = .002, cutpoint 26 mm) and neck length (P = .017, cutpoint 17 mm) were associated with endoleak, whereas some mural neck thrombus content was protective (P = .001, cutpoint 11° of circumferential coverage). CONCLUSIONS A limited number of independent anatomic variables are predictive of type Ia endoleak after EVAR, including aortic neck diameter and aortic neck length, whereas mural thrombus in the neck is protective. This study suggests that anatomic measures with identifiable threshold cutpoints should be considered when defining the hostile aortic neck and assessing the risk of complications after EVAR.

The Use of Prosthetic Grafts in Complex Military Vascular Trauma: A Limb Salvage Strategy for Patients With Severely Limited Autologous Conduit

BACKGROUND The use of prosthetic grafts for reconstruction of military vascular trauma has been consistently discouraged. In the current conflict, however, the signature wound involves multiple extremities with significant loss of soft tissue and potential autogenous venous conduits. We reviewed the experience with the use of prosthetic grafts for the treatment of vascular injuries sustained during recent conflicts in Iraq and Afghanistan. METHODS Trauma registry records with combat-related vascular injuries repaired using prosthetic grafts were retrospectively reviewed from March 2003 to April 2006. Data collected included age, gender, mechanism of injury, vessel injured, conduit, graft patency, complications, including amputation and eventual outcome of repair. RESULTS Prosthetic grafts were placed in 14 of 95 (15%) patients undergoing extremity bypass for vascular injuries. Patients were men with an average age of 25 years (range, 19-39 years). All prosthetic grafts in this series were made of polytetrafluoroethylene. Mechanism of injury included blast (n = 6), gunshot wounds (n = 6), and blunt trauma (n = 2), resulting in prosthetic repair of injuries to the superficial femoral (n = 8), brachial (n = 3), common carotid (n = 1), subclavian (n = 1), and axillary (n = 1) arteries. Mean evacuation time from injury to stateside arrival was 7 days (range, 3-9 days). Twelve grafts were placed initially at the time of injury, and two after vein graft blow out with secondary hemorrhage. The mean follow-up period was 427 days (range, 49-1,285 days). Seventy-nine percent of prosthetic grafts stayed patent in the short term, allowing patient stabilization, transport to a stateside facility, and elective revascularization with the remaining autologous vein graft. Three prosthetic grafts were replaced urgently for thrombosis. The remaining seven grafts were replaced electively for severe stenosis (3) or exposure (4) with presumed infection. There were no prosthetic graft blow outs or deaths in this series. No patients required amputation because of prosthetic graft failure. Three (21%) patients went on to have elective lower extremity amputation, despite patent grafts for nonsalvagable limbs. CONCLUSIONS When managing patients with multiple extremity trauma and limited noninjured autogenous venous conduits, emergent use of prosthetic grafts may provide an effective limb salvage strategy. Despite being placed in multisystem trauma patients with large contaminated soft tissue wounds, emergent revascularization with polytetrafluoroethylene allowed patient stabilization, transport to a higher echelon of care, and elective revascularization with remaining limited autologous vein.

Surgical trainee participation during infrainguinal bypass grafting procedures is associated with increased early postoperative graft failure

OBJECTIVE This study was conducted to determine the potential effect of surgical trainee participation during infrainguinal bypass procedures on postoperative graft patency rates. METHODS Data from the National Surgical Quality Improvement Program (NSQIP) Participant User Files from 2005 through 2009 were retrospectively reviewed, using propensity score matching, to identify all patients undergoing infrainguinal bypass grafting procedures, excluding those who had prior operation ≤30 days of the index procedure. A separate analysis was performed on a subset of procedures from the entire NSQIP sample that was matched on propensity for intraoperative surgical trainee participation. The primary predictor variable was intraoperative surgical trainee participation. The main outcome measure was the 30-day postoperative graft failure rate. RESULTS For the entire sample of 14,723 NSQIP patients undergoing infrainguinal bypass grafting, 30-day graft failure rates were significantly higher when a surgical trainee participated (5.8%) vs without participation (3.9%; P < .0001). For the cohort of 9234 patients matched on their propensity for intraoperative trainee participation, this difference in graft failure rate remained significant (5.0% with participation vs 4.0% without participation; P = .02). CONCLUSIONS Surgical trainee participation is an independent risk factor for technical failure after infrainguinal bypass grafting. Prospective evaluation is needed to determine the cause of this increase in graft failure rates for procedures that involve surgical trainees.

Cervical Spine Instability: Clearance Using Dynamic Fluoroscopy

Cle aring the cervical spine in a multiply injured trauma patient is a dilemma because clinical examination for ligamentous instability cannot be performed, and the standard cervical spine series can miss isolated ligamentous injury. Static flexion/extension views are unsafe, as the obtunded patient has no protective reflexes and cannot complain of pain during the exam. This results in a need for prolonged spinal immobilization and its attendant complications. Dynamic fluoroscopy may be useful in the detection of otherwise occult injuries.We performed a prospective study of a cervical spine clearance algorithm incorporating dynamic fluoroscopy with flexion/extension views. Inpatient records over a 3-year period were reviewed. Patient demographic data, results of cervical spine films and fluoroscopic exams, interventions based on positive results, and missed injuries were recorded.One hundred ten patients with normal spine plain films underwent dynamic fluoroscopy with flexion and extension views of the cervical spine. The average Glasgow Coma Score was 9.2 and the average revised Trauma Score was 9.5. Nine patients had evidence of cervical instability on exam. Six of these were deemed stable by the orthopedic or neurosurgical spine consultants, and these patients had their hard collars removed. One patient with positive findings had cervical immobilization with hard collar continued, a second had halo placement, and a third underwent spinal fusion for atlanto-occipital disassociation. No patients undergoing dynamic fluoroscopy were subsequently found to have missed cervical spine injury.With our protocol, 3 patients had significant cervical instability that would have been missed without dynamic fluoroscopy. Given the significant medical and legal ramifications of missed cervical spine injury and the benefits of early removal of cervical collars, more widespread use of dynamic fluoroscopy of the cervical spine is warranted.

Sixty-four Slice Multidetector Computed Tomographic Angiography in the Evaluation of Vascular Trauma

BACKGROUND Artifacts produced by metallic fragments and orthopedic hardware limit the usefulness of conventional computed tomography in many military trauma patients. Contemporary literature suggests that multidetector computed tomographic angiography (MDCTA) by resolving these limitations may provide a useful noninvasive alternative to invasive arteriography. The objective of this study is to review the utility of MDCTA in the evaluation of recent combat casualties with vascular injuries. METHODS Data on all vascular trauma patients seen by our service has been collected prospectively and entered into a database. A retrospective review was conducted of patients seen from August through December 2006 who underwent MDCTA. Patient demographics, mechanism of injury, modality of evaluation, and findings were recorded. RESULTS Twenty patients underwent MDCTA. Thirteen patients were injured by blast fragments. Seven patients were injured by gunshot wounds. Nineteen of 20 studies were diagnostic and one was judged to be indeterminate. Studies in nine patients identified arterial injuries. Multiple extremities were evaluated with a single study in 16 patients. Fifteen studies assessed the lower extremities, four the upper extremities and two the neck. Fourteen patients in this series had retained fragments, 10 had external fixators or intramedullary rods, and only 4 had neither retained fragments nor orthopedic hardware. MDCTA allowed for assessment of the arterial runoff despite hardware or fragments in 15 of 16 (94%) patients. Comparative studies were available in four patients in addition to MDCTA. There were no missed injuries in these four patients. CONCLUSIONS MDCTA yielded high resolution images that were very useful for the delayed evaluation of combat casualties. The presence of metallic fragments or orthopedic hardware did not significantly interfere with MDCTA. It is a reliable and promising alternative to traditional arteriography for evaluating clinically occult vascular trauma.

Outcomes of selective tibial artery repair following combat-related extremity injury

OBJECTIVE Selective tibial revascularization refers to the practice of vessel repair vs ligation or observation based on factors observed at the time of injury. Although commonly employed, the effectiveness of this strategy and its impact on sustained limb salvage is unknown. The objective of this study is to define the factors most relevant in selective tibial artery revascularization and to characterize limb salvage following tibial-level vascular injury. METHODS The cohort of active-duty military patients undergoing infrapopliteal artery repair comprises the tibial Bypass group. A similarly injured cohort of patients that did not undergo operative vascular intervention (No Bypass group) was identified. All tibial vessel injuries were documented by angiography. Data were compiled via medical records and patient interview. The primary outcome measure was failure of limb salvage. Multivariate regression was performed to identify factors associated with revascularization and to describe factors associated with amputation. RESULTS Between March 2003 and September 2008, 135 of 1332 patients with battle-related vascular injuries had documented tibial vessel disruption or occlusion. Of these, 104 were included for analysis. Twenty-one underwent autologous vein bypass at the time of injury (Bypass group), and the remaining 83 patients were managed without revascularization (No Bypass group). Mean follow-up (39 vs 41 months; P = .27), age (25 vs 27 years; P = .66), and mechanism of injury (88% vs 92% penetrating blast; P = .56) were similar, but the No Bypass group had higher Injury Severity Scores (ISS; 16.3 vs 11.7; P < .01). Injury characteristics, including Gustilo III classification (49% vs 43%; P = .81) and nerve injury (55% vs 53%; P = 1.0), were similar. Subjects were more likely to receive tibial bypass with an increasing number of tibial vessel occlusions and documented ischemia on initial exam. However, of the 23 in the No Bypass group with initially unobtainable Doppler signals, 17 (74%) regained pedal flow following resuscitation and limb stabilization. Amputation rates were similar (23% vs 19%; P = .79), but the prevalence of chronic limb pain was lower in the Bypass group (10% vs 30%, respectively; P = .08). Cox regression analysis of amputation-free survival demonstrated an association between mangled extremity severity score >5 (hazard ratio [HR], 2.7; P = .01) and amputation. CONCLUSIONS This report provides outcomes data for wartime tibial vascular injury, which supports a selective approach to tibial artery revascularization. Clinical factors such as ISS and degree of ischemia guide which patients are best suited for tibial vascular repair, while injury-specific characteristics are associated with amputation regardless of revascularization status.

Risk Factors for Early Failure of Surgical Amputations: An Analysis of 8,878 Isolated Lower Extremity Amputation Procedures

BACKGROUND There are very few data currently published on risk factors for early failure of lower extremity amputation procedures. STUDY DESIGN All patients from the 2005-2010 American College of Surgeons NSQIP database who underwent isolated lower extremity amputation were included for analysis (excluding patients with earlier operation within 30 days, patients undergoing an open amputation, and patients undergoing another procedure during amputation). Multivariate logistic regression was used to determine predictors of early amputation failure (defined as need for reoperation within 30 days postoperatively) after adjustment for a number of preoperative and intraoperative variables. RESULTS A total of 8,878 patients were included for analysis (4,258 below-knee amputations [BKA]; 3,415 above-knee amputations; and 1,205 transmetatarsal amputations). Overall rate of early amputation failure was 12.7% (12.6% for BKA, 8.1% for above-knee amputations, and 26.4% for transmetatarsal amputations; p < 0.0001). Several pre- and intraoperative variables appeared to be independently associated with early amputation failure, including emergency operation, transmetatarsal amputation (reference = BKA), sepsis (reference = no sepsis), septic shock (reference = no sepsis), end-stage renal disease, systemic inflammatory response syndrome (reference = no sepsis), intraoperative surgical trainee participation, body mass index ≥30, and ongoing tobacco use. Characteristics associated with decreased early amputation failure include age 80 years or older (reference = younger than 65 years), locoregional anesthesia, above-knee amputation (reference = BKA), operative time 40 to 59 minutes (reference = <40 minutes), operative time ≥80 minutes (reference = <40 minutes), and operative time 60 to 79 minutes (reference = <40 minutes). CONCLUSIONS Increased operative time and heightened supervision of participating surgical trainees can decrease the risk of early amputation failure. In addition, specific clinical situations, such as sepsis or emergency procedures, should prompt vascular surgeons to consider either an open amputation procedure or a more proximal closed amputation.

Retrieval of iatrogenic intravascular foreign bodies

Malposition, embolization, fracture, and migration of endovascular devices are unfortunate consequences of endovascular intervention and will be encountered at some point by nearly every practitioner. The existing literature on foreign body retrieval consists of large single-institution series and case reports. We provide an overview of this recent literature, clarifying what devices are being lost, what symptoms occur as a result, and how retrieval is being performed. We have identified all case series and case reports since the year 2000, summarized the results, and made some general observations and recommendations that may be useful to the practitioner faced with the prospect of retrieving a fractured medical device, malpositioned coil, or migrated inferior vena cava filter.