Vascular Extremity Trauma

Etiology

Peripheral vascular trauma can occur in either the civilian or military setting.  From there it subdivides by the mechanism of injury (which can be blunt, penetrating, or combination) and anatomical location (upper or lower extremity). Penetrating trauma can be from objects that are missiles (e.g., bullets, fragments from a blast, etc.) or stabs (e.g., knife, coat hangers, keys, etc.). Blunt trauma occurs secondary to fractures or dislocations.[1]

Epidemiology

Civilian patients with vascular injuries (central and peripheral) account for 1% to 2% of all injuries reported in trauma patients.  However, these injuries account for greater than 20% of all trauma-related deaths.[3] Penetrating extremity trauma (PET) is the leading cause of peripheral vascular injuries, as they account for 75 to 80% of these injuries. Projectiles from handguns account for 50% of these injuries, followed by stab wounds (30%), and shotguns (5%). In this setting, the most common arterial injury is that of the femoral or popliteal arteries which occur in 50% to 60%  followed by the brachial artery which occurs in 30% of traumatic arterial injuries (west trauma). Blunt trauma (fractures, dislocations, crush, and traction) account for the other 5 to 25% of peripheral vascular injuries.[1] In the civilian setting, this accounts for less than 1% of all fractures.[4]

The reported rate of vascular injuries in the military setting has changed significantly since World War I (WWI) until the present.  The rate in WWI was reported to be 0.4% to 1.3% and in World War II 0.96%. The rate increased slightly during the Korean and Vietnam wars to a rate of 2% to 3%.  However, the rate increased to 12% during the recent tours in Afghanistan and Iraq. Of these injuries, the extremities were the most commonly reported at 79%, with 66% of those occurring in the lower extremity.[5]

Blunt vascular injuries more commonly occur within the torso secondary to motor vehicle accidents.  For the extremities, there are a few specific dislocations or fracture patterns that correlate with vascular injuries.  The injuries include supracondylar fracture of the humerus, posterior knee dislocation, or tibial plateau fracture. These injuries correlate with high morbidity and mortality.[6]

Perkin et al.[7] did a retrospective observational study of vascular trauma over a period of 6 years (256 patients; 135 penetrating and 121 blunt) at The Royal London Hospital. There was a male predilection with a mean age of 29 years; the general trauma patient was also more commonly male with a mean age of 32 years.  In this study, the authors divided the vasculature system into three anatomical zone: Junctional Zone (carotid, vertebral, jugular, external iliac, common femoral, profunda femoris, subclavian and axillary vessels, along with branches of the aortic arch), Extremity Zone (vessels distal to the Junctional Zone) and Central Zone (vessels proximal to Junctional Zone).  Central Zone injuries were the most common followed by Extremity Zone injuries.  Patients with penetrating trauma were more likely to be admitted for vascular rather than general trauma.  Blunt vascular injuries correlate with higher odds of death, three times that of penetrating and a 50% mortality rate if it occurred with an injury at the Junctional Zone.  The authors concluded that this was due to the significant force that was necessary to cause these injuries.  Overall, vascular trauma when compared to general trauma, required more blood transfusions (76% of vascular trauma vs 16% of general trauma), longer hospital stays (12 days for vascular vs 2 days for general trauma), and more critical care management (49% of vascular trauma admitted to intensive care vs 28% of general trauma).  Comparison of blunt and penetrating vascular injuries revealed that blunt vascular injuries required more blood transfusions (mean packed red blood cells units 9 vs. 4), longer hospital stays (mean of 35 days vs. 7 days), and more critical care admissions. 

Barmparas et al.[8] reviewed the National Trauma Databank for vascular injuries in pediatric patients.  Males made up 74% of the patients with a mean age of 10.7 years old.  The four most common modes of injuries were firearms, stabbing, motor vehicle collisions (MVC), and falls.  The overall incidence of trauma-related vascular injuries in the pediatric population is 0.6%.  The most common vessels injured were the brachial, radial, and ulnar vessels. When compared with adults, penetrating vascular injuries were less common (42% vs. 51%), and overall mortality was less (13% vs. 23%).   The rate of lower extremity amputations was similar for pediatric and adult patients; however, the pediatric population has a lower mortality rate.  The authors conclude that the difference in mortality is likely due to the pediatric population having more isolated upper extremity vascular injuries and the adult population having diseases vasculature (atherosclerosis and calcified vessels).  Children also required fewer fasciotomies (13% vs. 20%).  Pediatric patients divided into four groups: infants (<1 year old), early childhood (1 to 5 years old), middle childhood (5 to 11 years old) and adolescent (11 to 16 years old).  The highest mortality with vascular injuries was in infants. 

Konstantinidis et al. noted that geriatric patients (>65 years old) make up a small percentage (7.6%) of vascular trauma. Blunt trauma is by far a more common cause of vascular injuries in this population as penetrating injuries account for only 16.1% of all injuries.  Males (60.8%) still account for a majority of vascular trauma with the mean age being 70.7 years old.  The overall incidence of trauma-related vascular injuries is 0.7%.  The four most common mechanisms for traumatic vascular injuries are once again MVC, firearms, stabbing and falls.  MVC account for 59.2% of vascular injuries in this population.  The most common vascular injury occurs within the chest.  When penetrating vascular injuries occur, they are more common in the neck or the upper extremity.  There is no difference in the amputation rate.  If an upper extremity amputation is required the most frequently injured vessel is the brachial artery.  Similar to pediatric patients, geriatric patients undergo few fasciotomies in comparison to the adult population.  Geriatric patients have an increased mortality associated with vascular trauma.  These patients have a 4-fold higher mortality rate and are more likely to perish in the emergency room, as 10% will do so verus 5.3% of the general adult population.  When admitted to the hospital these patients have a slightly longer ICU stay (9.4 days vs. 8 days) but their length of hospitalization is no different than that of a general adult.[9]

History and Physical

As with all trauma patients, advanced trauma life support (ATLS) protocol should be followed as with any patient that presents to the trauma bay.  After completion of airway and breathing evaluation, assessment of circulation is next.  The management of vascular injuries has its basis the concept of hard or soft signs.  The WTA and EAST each have different definitions of hard signs and soft signs.  The WTA defines hard signs as expanding hematoma, bruit, thrill, external bleeding, pulselessness, pallor, paresthesia, paralysis or pain. The WTA recommends using the hard signs for major named arteries, which includes anything proximal to the anterior tibial artery or tibioperoneal bifurcation but it excludes the profunda femoris artery.  The EAST defines hard signs as pulsatile bleeding, thrill, pulse deficit, bruit or expanding hematoma.  The definition of soft signs, per the WTA, is a history of arterial bleeding at the scene or in transit, neurological deficit occurring in a nerve adjacent to a name artery, proximity of the injury to name artery or a small nonpulsatile hematoma present over an artery.  The EAST definition of soft signs is the same as the WTA.[1][10]  The finding of a single soft sign has approximately a 10% rate of vascular injury.  In comparison, two or more soft signs can have a vascular injury rate of 25%.[11]

When assessing circulation, pulses in the extremities should undergo palpation first. For overt vascular injuries noted on the initial survey, such as active bleeding, manual compression or a compressive dressing should be attempted to control hemorrhage.[1]  If manual compression fails to control hemorrhage, there is level III evidence to support the use of a tourniquet until definitive repair.[10] Patients with hard signs require immediate operative intervention.  If no hard signs are present, then one will move onto the next assessment in the primary survey.  Once the primary survey is complete, the secondary survey occurs, and this is where soft signs for vascular injuries will undergo evaluation. Being able to palpate pulses that are equal bilaterally is a good indicator that no arterial injury or a very limited arterial injury is present.  However, even with the ability to palpate equal pulses bilaterally, additional studies need to be obtained to provide a complete examination of the patient.[1]

When evaluating traumatic extremities injuries, if it appears severe, one must decide if the limb is salvageable.  A mangled extremity will have injuries to three of the four functional components (vessels, soft tissue, bone, and nerves).  Multiple scoring systems have been created to predict limb salvage including the Mangled Extremity Severity Score (MESS), Predictive Salvage Index, NISSSA score, Limb Salvage Index and Hannover Fracture Index.[12]  The MESS is probably the most well known of these and consists of various points (age, extremity injury type, ischemia of wound and hypotension/shock) that are calculated to help determine if amputation is likely needed. (Johnson et al. determined that a score greater than 7 predicts a 100% need for amputation; study evaluated 25 patients.)[13]  However, in larger studies, these scoring systems have failed to prove effective in predicting the need for amputation.[12]

Evaluation

Standard trauma labs should be obtained at the time of presentation.  Depending on the mechanism of injury and stability of the patient pertinent imaging should be obtained. 

Frykberg et al. did an observational study (2,674 trauma Pt in 1 year;  of which 366 had PTE) to determine if the physical exam was an accurate and safe modality to be the sole method of evaluation for vascular injuries. For penetrating extremity trauma, the conclusion was that if hard signs are present, a patient requires operative intervention, because, in this study, all patients with hard signs were noted to have a major vascular injury at the time of operative intervention.  If there is a need to localize the vascular defect (multiple fracture or GSW), then an arteriogram (in an emergency room or operative suite) or duplex ultrasound can be attempted.[1] EAST recommend that restoration of perfusion be done within 6 hours to maximize salvage of the limb.[10] 

A normal pulse exam can be present in 5% to 15% of patients with vascular injuries.[2]Overall, the incidence of arterial injuries in patients with soft signs is 3% to 25%.[6][14] Considering this apart from the physical exam, an ankle-brachial index (ABI) to brachial-brachial index (BBI) or arterial pressure index (API) is required. If the index is =0.9, then additional imaging studies are not needed as the sensitivity and specificity are greater than 95%.  Older patients are at higher risk for arterial disease, and these studies may not be as accurate.  To account for this the contralateral limb's ABI/API is recorded.  If the injured extremity's ABI/API is =0.1, additional imaging is necessary. The effectiveness of API was noted in a study by Lynch and Johannsen. In this study, they found that an API < 0.90, had a sensitivity of 87% and a specificity of 97% for arterial disruption when compared to arteriography.  When they compared it to clinical outcomes, the sensitivity, and specificity increase to 95% and 97%.[15]  For stable patients with an abnormal physical exam or ABI/API, arteriography, CT arteriography, or duplex ultrasound should be ordered to localize the injury.   

Multiple studies within the literature have concluded that CT arteriography (CTA) has a high sensitivity and specificity in the evaluation of traumatic arterial injuries of the extremities. There are other advantages of CTA including non-invasive, rapid evaluation and readily available.  Disadvantages include poor arterial opacification, inability to intervene, streak artifacts, and increased need for larger IV contrast load.[16][1] Per the EAST, there is level I evidence to support CTA as the imaging modality of choice.[10] Standard arteriography (digital subtraction after intra-arterial or intravenous contrast injection, conventional films or surgeon performed study) is a more invasive study but can be done in the operative suite and allows for on-the-spot intervention. The proximity of wound to the artery does not justify arteriography, as it is invasive, costly, and physical exam has been shown to provide essentially the same information. The small number of injuries that eventually require surgical intervention are treated successfully at that time of operative intervention without any increase in morbidity. Duplex ultrasound is another option for evaluation of vascular injuries. The major limiting factor to ultrasound is having experienced staff to operate and interpret the exam. Specificity is reported to be at 95%. However, sensitivity ranges from 50% to 100%.[1]

Treatment / Management

Findings on imaging that require immediate operative intervention include pulsatile hematoma, extravasation of contrast or early pseudoaneurysm, occlusion or AV fistula of a major named artery.  If there is extravasation, AV fistula, or occlusion is noted in an artery that is not considered to be one of the major named ones (profunda femoris, anterior tibial, posterior tibial or peroneal artery), then observation (occlusion) or therapeutic embolization (AV fistula or extravasation) can be done. The recommendation is that in 3 to 5 days a repeat arteriogram or duplex ultrasound be done to rule out pseudoaneurysm or pulsatile hematoma which can develop secondary to distal backflow.[1]

If an intimal defect is present on imaging, no invasive intervention is necessary as 87% to 95% will heal without vascular operative intervention. The patient can be placed on heparin or aspirin for prophylaxis as long as there is no contraindication. Urgent imaging is necessary if there is an abrupt change in the flow to an extremity or signs of AV fistula or pseudoaneurysm.[1]

The peripheral artery can spasm (common in younger patients), and this is visible on imaging. Rewarming of the extremity is advisable as long as there are signs of good distal flow.  Other pathologies must merit consideration and monitoring including compartment syndrome, in situ thrombosis or distal embolism.  If the spasm is severe and threating the limb, there are numerous intra-arterial treatments that can be attempted which include: papaverine bolus of 60 mg followed by infusion of 30 to 60 mg/h, nitroglycerin of 50 to 100mg or infusion of 1000 mL of normal saline plus 1000 units of heparin 500 mg tolazoline at a rate of 30 to 60 mL/h.[1]

Preparation and draping for operative intervention should be done in a fashion that allows for proximal and distal control, as well as any area where a fasciotomy would be performed.  In the upper extremity, skin prep is done from the chin to umbilicus, from the contralateral nipple to ipsilateral fingernails and includes one of the lower extremities to the toenails. For lower extremity intervention, the preparation is from the nipples to bilateral toenails.[17]

If the injured vessel is <100% transected with minimal tissue loss, an interrupted or continuous repair of the vessel can be done with 6-0 or 7-0 polypropylene.  If complete transection has occurred, the artery should be debrided back to healthy intima. Evaluate for the tension that will be present when an end-to-end anastomosis is under consideration. If tension is too great, then the proximal and distal branches can be ligated to gain up to 3 cm of total advancement from both ends.  Care is necessary when attempting ligation of the geniculate collaterals from the popliteal artery.  For transactions in arteries that are distal to the axillary artery or common femoral artery that are less than 1 cm in diameter, a spatulated end-to-end anastomoses with 6-0 or 7-0 polypropylene can be done.  If the diameter is more than 1 cm than a non-spatulated, end-to-end anastomosis with 6-0 or 7-0 polypropylene is a choice for repair.  If a segmental loss is present, then an interposition graft autogenous (greater saphenous vein) or ringed polytetrafluoroethylene (PTFE or Teflon) can be placed.  Due to its high long-term patency rate, the greater saphenous vein is the conduit of choice.  If the greater saphenous vein is not usable, then the lesser saphenous vein is another option. In the upper extremity, the basilic or cephalic veins are options.  If no autogenous grafts are available, then PTFE graft can be placed.[17]

The repair of a vascular injury should never be left exposed as this increases the risk for infection. If there is inadequate healthy tissue to cover the repair, then the surgeon needs to consider (possible consultation to a plastic surgeon) if a transposition or rotational muscle flap will be necessary.  If a muscle flap cannot be done, then a vacuum-assisted device or open packing can be placed.[17]

After repair of a peripheral artery a completion arteriogram should be done in a stable patient if there was a delay in diagnosis and/or treatment, complex repair done (segmental resection and an end-to-end anastomosis or insertion of an interposition graft), if palpable pulses are not present distally after repair or there is concern for narrowing at anastomosis. Metal clips can be placed at the distal and proximal end of the repair to aid with the arteriogram.  If the anastomosis appears narrowed and the patient is stable, cut out the polypropylene suture, debride any questionable tissue (especially adventitia) and if the artery appears to be in vasospasm, a dilator (Garrett coronary artery or Bakes biliary) can be inserted. It is recommended to use an interrupted suture technique if a continuous technique was used the first time.[17]

A patient that is hemodynamically unstable may not be suitable for placement of an autogenous graft. Therefore, lateral arteriography should be covered with a porcine xenograft under mesh gauze soaked in saline-antibiotics.  A temporary intraluminal shunt is inserted with a porcine xenograft under mesh gauze soaked in a saline-antibiotic solution to cover it. Upon achieving patient stability, he or she can return to the operating room for a more definitive intervention.[17]

If limb salvage is the treatment choice, the first step of the procedure is to establish arterial inflow via insertion of a temporary intraluminal shunt. Several shunts are options, including intravenous tubing or carotid artery-type shunts.  For large peripheral veins (popliteal or femoral), 16-24 Fr thoracostomy tubes are a viable option.  Palpable pulses or doppler flow at the wrist or ankle establish that the shunts are functional.  The exact time frame that a shunt can remain in place is unknown but the longer that one is left in places the patient at increased risk for complications such as thrombosis.  After removal of the shunt, an autogenous graft or extra-anatomic bypass should be performed.[17]

If the patient is at increased risk for compartment syndrome (delay in treatment, significant swelling of extremity, neuromuscular findings or need for simultaneous arterial and venous clamping along with venous ligation) a fasciotomy can be done.  Compartment pressure can be measured if there is an abnormal completion arteriogram.  If the pressure is >30 mmHg, then a fasciotomy is done.  Historically, there was a 20% return to the operating room to perform a delayed fasciotomy, the goal of the aforementioned is to avoid this.[17]

No antibiotic guidelines exist for GSW associated fracture.  For low-velocity GSW related fractures, some recommend antibiotics (either short IV course or short outpatient course) if the case is being managed non-operatively, while others feel that antibiotics are not necessary as multiple studies have suggested that there is no difference in the infection rate.  In the studies, the most common antibiotic class used was cephalosporins.  There is also debate on the need for debridement on these non-operative fractures; no definitive evidence is present to settle this debate.  For high-velocity GSW related fracture, once again, no high-quality studies exist.  The consensus is that debridement and antibiotic therapy is necessary.[18]

Differential Diagnosis

Five different arterial injuries can occur with either blunt or penetrating injuries.  The five different injuries include complete wall defect (hemorrhage or pseudoaneurysm), intimal injury (subintimal/intramural hematomas, flaps, disruptions), arteriovenous (AV) fistula, complete transection (with hemorrhage or occlusion), and spasm. Blunt traumas are most commonly associated with intimal defects, whereas, penetrating trauma correlates with defects of the wall, complete transection or AV fistulas.[2][1]

Prognosis

Overall, patients with penetrating extremity trauma can be safely discharged to home if pulses are present and equal bilaterally at the wrist (or ankles) or ABI to API ratio = 0.9 in an injured extremity.  The WTA notes that this includes patients that are post-reduction for posterior knee dislocations. Discharged patients should have close follow up as 1% to 4% will have progression of a small injury not seen at the time of initial evaluation that requires operative intervention.[1]  The median delay between injury and diagnosis in one study was 10 days.[19]

Complications

A significant complication of penetrating trauma is acute compartment syndrome; this is a surgical emergency as it causes tissue ischemia and eventually necrosis.  In general, reversible neuropraxia can occur with ischemia time of one hour.  If the ischemia time continues to the four-hour mark, it correlates with irreversible axonotmesis, and if it goes longer than six hours, necrosis can occur and be irreversible.  There are common areas within the body where compartment syndrome can occur.  The areas that are most common include below the knee, thigh, forearm, and arm.  Of these the most common site is below the knee.  Studies have demonstrated that one can predict the risk of compartment syndrome based on the site of injury.   The risk of compartment syndrome occurring with a proximal below the knee injury (proximal tib/fib fracture) is much high than a distal below the knee injury (middle or distal fracture).  Fracture of the lower extremity is the leading cause of compartment syndrome. Patients that have an injury to both the venous and arterial system are at high risk.[20]  Acute compartment syndrome can be challenging to diagnosis on physical exam, especially in a trauma patient, as multiple confounding issues are present. Classically the 6 'P's' are taught.  There are pain, pallor, pulselessness, poikilothermia, paresthesia, and paralysis.  Unfortunately, data to support the 6 'P's' for acute compartment syndrome is lacking.  Pain is usually an early symptom.  The pain is described as "being out of proportion to the exam."   On physical exam, one can attempt to passively stretch the toe or finger to assess if pain is present, which is often the earliest physical exam finding. Other suggest that a loss of two-point discrimination is an early sign.  Studies suggest that the above clinical signs have poor sensitivity and specificity.[21]  Shuler et al.[22] looked at the ability of a physical exam to assess the firmness of a compartment and concluded that manual detection is not adequate.  Compartment syndrome should have vigilant monitoring even when managing an open fracture, as this does not mean that the compartments cannot be compressed. Compartment pressures are measurable with a handheld manometer (Stryker device).  If the delta pressure is <30 mmHg, then a fasciotomy is needed.[20]  Another issue that one needs to be aware of is lead shrapnel within a synovial fluid as this fluid as a solvent for the lead, and this can lead to lead toxicity.[18]