Prehospital tourniquet use is one of the more controversial topics in the trauma community. Despite the potential advantages of using tourniquets in a prehospital setting to control extremity hemorrhage, their use has been debated due to their potential complications. The debate over tourniquet use began in the Civil War as surgeons started seeing ischemic complications secondary to their placement. Conversely, many argue that tourniquets still confer the benefit of saving lives that may otherwise have been lost from uncontrolled hemorrhage [6].

Controversy exists because the use of tourniquets has long been feared in the civilian world due to concern over improper use. Serious complications can arise if tourniquets are left in place too long, resulting in limb ischemia, muscle injury, nerve deficits, gangrene, and even amputation (Table 21.1).

These unfortunate side effects are inherent in the physiology behind how and why a tourniquet works. They function by radially compressing muscle and soft tissues that surround extremity artery and veins. This then compresses the lumens of these vessels to completely arrest distal flow both into and out of the extremity. Generally, the risks increase in limbs with larger circumference, given that this correlates with a higher tension required to stop arterial flow.

Prolonged tourniquet application more than 1.5–2 h can result in tourniquet palsy or tourniquet paralysis from injury to extremity muscles or nerves. Overall tourniquet time is important because it has been shown in animal studies that while after 1 h, little to no muscle damage was seen, 2 h of tourniquet time led to elevated levels of lactic acid and CPK, suggesting some degree of muscle damage, and 3 h or more led to myonecrosis of the muscles directly beneath the tourniquet. Nerve injuries have been reported after only 30 min of tourniquet time. Irreversible ischemic damage occurs after 6 h of tourniquet placement, and in this case, amputation of a limb above the level of tourniquet placement is routinely recommended. The less severe phenomenon known as post-tourniquet syndrome is a clinical entity comprised of extremity weakness, paresthesias, pallor, and stiffness. This constellation of symptoms is common after any length of tourniquet placement but seems to resolve in around 3 weeks [7].

Tourniquets are also associated with venous complications. They are a known cause of venous thromboembolism due to the venous stasis that occurs during their use, and these clots have the potential to embolize once the tourniquet is removed. Paradoxically, inappropriate usage when arterial injury does not exist can actually increase extremity bleeding by occluding venous return while not completely arresting arterial flow [8].

Despite this seemingly daunting list of complications, the military success and lives saved attributed to tourniquets are noteworthy as limb loss and limb trauma due to explosive injuries are so common. In this setting, military individuals, who are well trained in tourniquet use, demonstrate an associated complication rate less than 2 % [9]. Hence, contemporary EMS training now embraces the use of tourniquets in the right circumstances. Tourniquet use also has application in the use of mass casualty triage where EMS personnel can stop extremity hemorrhage in patients quickly and effectively and then move on to other victims who also require prompt attention. Guidelines regarding proper tourniquet application are evolving and vary among regions (Table 21.2). The pervasive rule, however, remains that tourniquet time should be minimized whenever possible and that total application time should not exceed more than 2 h [6–9]. In the civilian setting where transport times are typically short, prolonged placement of a tourniquet should be of little issue. On the contrary, in rural settings where transport times can be prolonged, the use of tourniquets remains controversial due to increased associated risks and guidelines must be established.

The safest tourniquets are made of uniform, smooth material with rounded, rather than sharp, edges, and wider devices are more effective. Pneumatic tourniquets such as blood pressure cuffs provide a more uniform pressure over a wide area, but their use is limited by their inability to maintain high pressures for long periods of time. The pneumatic tourniquet used by many surgeons today was developed in 1904 and has the advantage over previous versions of providing more uniform pressure around a limb, as well as being easier to place and remove. Surgical tourniquets should be placed over the thickest portion of the affected limb in order to maximize the amount of tissue through which pressure is exerted. This is contrary to military and EMS tourniquets which should be placed in close proximity to the wound as to preserve maximal limb length in the event limb loss occurs at the level of the tourniquet. Proximal placement of tourniquets allows for speed of application, minimization of pressure injury, and better hemorrhage control in the event that multiple distal bleeding sites exist [7–10].

In 2014, the American College of Surgeons Committee on Trauma convened a panel of nationally recognized experts in prehospital trauma care to develop an algorithm for prehospital external hemorrhage control recommendations (Fig. 21.1). Generally, based on the evidence for survival benefits, they strongly recommended the use of tourniquets in the prehospital setting when direct pressure is ineffective or impractical. The panel also suggested against releasing a tourniquet properly applied in the field before the patient reaches definitive care; however, the evidence for this recommendation was less strong [10].

It has been common teaching that once a tourniquet is placed, it should be left in place until assessment by a physician, regardless of the “tourniquet time.” This is due to the relatively short transport times seen with most emergency medical services; however, it is also acceptable for reassessment and possible de-escalation to a pressure dressing, should circumstances permit. This has significant relevance in the tactical and triage arena where an extreme early intervention was chosen but when circumstances permit may, in fact, be medically excessive [7]. Typically “reperfusion intervals” wherein the tourniquet is released are not effective at reducing complications unless perfusion is restored for a full 30 min or more. However, this could potentially lead to life-threatening exsanguination, so proposed algorithms have been created that can help determine the ongoing need for a tourniquet or if removal is a possibility (Fig. 21.2) [11].

In general, safe prehospital tourniquet use depends on a number of factors, including tourniquet design, placement location, tourniquet tightness, and tourniquet time. Fundamentally, for tourniquet use to gain more widespread acceptance, specific protocols need to be set in place, and regular training on these protocols for prehospital providers is required.

The implementation of arteriography gives surgeons the best chance to avoid negative traumatic wound explorations in the case of extremity trauma. Given the cost, time, invasive nature of angiography, and potential nephrotoxicity from the contrast dye, routine contrast imaging of all patients presenting with extremity trauma has been abandoned, due to the large percentage of normal studies that resulted. Now it is the practice in most trauma centers to perform selective arteriography on patients who present with increased suspicion for extremity arterial injury, often based on proximity of the injury to the neurovascular bundle. Suspicion in these patients arises based on “soft signs” of vascular injury noted on physical exam or Doppler ankle-brachial indices (ABI) of less than 0.9, both of which are considered indications to pursue arteriography [16]. Other indications for angiography include complex soft tissue injuries and fractures, large hematomas in proximity to the injury, any subjective neurological or vascular compromise, chronic vascular disease, multiple potential sites of injury, and thoracic outlet injuries. Based on the results of the angiogram, those with no signs of vascular injury may be observed, those with minimal vascular injury may be observed or serial angiograms can be performed, while those with major arterial injuries require either an operative exploration or endovascular intervention [1, 16].

Drawbacks to angiography include its costliness, potential for suboptimal and useless studies, and the high rate of negative studies that result from overuse. Additionally, obtaining this imaging can cost valuable time in the event of an ischemic limb. Arteriography can cause a delay of up to 3 h prior to definitive repair, which can translate to critical time lost and contribute to prognosis and limb salvage [17].

Handheld Doppler flow detectors screen for arterial injury by determining the phasic Doppler signals in a potentially injured vessel and can be used to determine the ABI in an extremity. This modality is useful to objectively establish the absence of flow in a vessel deemed to be pulseless on physical exam or if the exam is asymmetric. However, the presence of Doppler signals in the absence of a palpable pulse does not exclude a vascular injury, as signals can occur from collateral flow or from flow around or through a transected, partially transected, or thrombosed vessel [1]. Regardless, Doppler flow is an inexpensive, noninvasive, and easy method of confirming physical exam, as well a useful tool for serially monitoring any vascular reconstruction postoperatively. If ABIs are performed, a result of less 0.9 in otherwise healthy patients is considered abnormal and warrants further imaging [18].

The technology and diagnostic utility of duplex ultrasonography continues to improve. Ultrasound as a technique for extremity vascular trauma has several advantages in that it is noninvasive, painless, portable, and relatively inexpensive while still screening for extremity arterial injury with similar accuracy as arteriography [1]. Ultrasound can be used to follow exams serially and can be done at bedside by a non-physician. Additionally, the direction of blood flow within a vessel can be assessed by color flow Doppler. The sensitivity of ultrasound for a traumatic vascular injury has been reported to be 67–95 %, while its specificity and accuracy are more than 98 % [3, 19]. The primary limitation to its use is operator dependency. Accuracy is thus reflected at institutions with well-trained vascular technologists and interpretations by physicians [3, 20].

The advent of computer tomographic arteriography (CTA) is quickly making it the diagnostic test of choice o ver conventional angiography to evaluate vascular trauma. Improved technology that allows for multiplanar and three-dimensional reformatting allows for simultaneous imaging of vasculature and adjacent body structures, allowing for the diagnosis of multiple consequences of any trauma with one single examination [21]. This can provide the surgeon with a priority guide for perioperative planning in the setting of other injuries. This can also eliminate any delays associated with calling in a team to perform conventional angiography. CTA has the advantages of being readily available in most hospitals and of being easy to interpret. It requires the administration of contrast material, which carries nephrotoxic risks, making subsequent need for contrast in the setting of endovascular interventions a consideration. Sensitivity and specificity are reported to be more than 90 % and equivocal to that of conventional angiography [22]. One critical limitation that must be mentioned relative to CTA revolves around penetrating trauma with retained metallic foreign body or patients with metallic surgical implants. In this setting the CTA can be difficult or impossible to interpret, especially when the associated metallic scatter is in proximity to the vascular area in question. This can severely limit the value of CTA and must be considered, as traditional angiography would then be the preferred test of choice [3, 21, 22].

Although magnetic resonance arteriography (MRA) has increased in popularity as a diagnostic tool for vascular diseases in the general public, in acute traumatic situations, it is infrequently utilized. While MRA has the advantage of being specific, noninvasive, and not requiring contrast agents, its price, lack of accessibility in many hospitals, and contraindication in patients with metallic orthopedic implants make it impractical for use in acute extremity vascular trauma [3]. Artifacts due to metallic foreign bodies may interfere with interpretation of MRA images; however, of more concern is the risk of movement of the foreign object once placed in a high magnetic field. While magnetic deflection of various bullets and shotgun pellets is uncommon, the probability of migration cannot be predicted due to ferromagnetic contaminants that are commonly present in ballistics. Generally, MR imaging of patients with retained ballistic fragments is considered safe, but the indication for imaging, possible types of bullet present, and location of bullet fragments should all be considered. If the fragments are not associated with a vital organ such as brain, spinal cord, eye, or heart, or if the metallic fragments are clearly nonferromagnetic, MRA can be considered [23].

Vessels can be injured in a number of ways secondary to trauma (Fig. 21.4). The most common forms of injuries sustained are lacerations or transections. A laceration is a full-thickness tear in a vessel where part of the wall remains intact, thus preserving vessel continuity. Mild lacerations involve less than 25 % of the wall, moderate lacerations involve 25–50 % of the wall, and severe lacerations involve more than 50 % of the wall. Oftentimes distal pulses persist in the case of lacerations. A transection is complete division of a vessel with a loss of continuity. This injury can be more difficult to approach and require a more extensive exploration, as the transected ends of the vessels tend to retract and constrict. This frequently causes thrombosis and cessation of hemorrhage, making diagnosing and identifying these injuries more complex. Most complete transections are coupled with loss of pulses, pain, pallor, paralysis, and paresthesias of the affected limb given the development of ongoing tissue ischemia [1].

Arteriovenous fistulas develop when concomitant injuries occur to a neighboring artery and vein and an abnormal connection is created between the two. This can pressurize the vein and can lead to rupture of affected vessels, thrombosis, embolization, high-output cardiac failure, and impingement on surrounding nerves and soft tissues. Physical examination can reveal a bruit, murmur, or a thrill over the site of injury. However, diagnosis is often missed if physical findings are not present, in which case arteriovenous fistula can be picked up on angiography, CTA, or ultrasound [1, 24].

Vascular contusions are bruises of the arterial wall. Contusions can be mild and involve only the adventitia, causing no consequences of injury, or they can extend into the intima, causing constriction, occlusion of vessel lumen, or intimal rupture and subsequent thrombosis. Large contusions can cause full-thickness weakening of the arterial wall and create true arterial aneurysms [1, 25]. Alternatively, a false or pseudoaneurysm occurs when bleeding from injured vessels is contained within the vessel, muscles, or fascial compartments. Arterial spasm occurs as a myogenic reflex response to surrounding injury. This manifests as an area of narrowing seen either on angiography or on arterial exposure [1].

Nonoperative management of traumatic vascular injuries is a controversial subject. While many surgeons insist that all arterial injuries require repair, there are many who believe that clinically asymptomatic injuries found to be minimal and nonocclusive by angiography may be managed without exploration [3]. A nonoperative approach can typically be employed when the vascular injury is of low-velocity mechanism and associated with intact distal circulation, has no active hemorrhage, and has less than 5 mm of arterial wall disruption in the event of intimal defects and/or pseudoaneurysms [14]. A large majority of nonocclusive arterial injuries have a self-limiting course and can resolve spontaneously in about 3 months. A small percentage may form false aneurysms and require surgical intervention, but no adverse sequelae seem to occur related to treatment delay. In the event of nonoperative management, it is typically recommended that the patient undergo some form of repeat imaging to confirm stability of the lesion and rule out acute thrombosis or distal embolization [26].

Endovascular interventions have grown in popularity over the last decade for the management of acute traumatic vascular injuries. Over a 9-year time span, the National Trauma Data Bank reports that the use of endovascular techniques to repair vascular traumas jumped from 2.1 % of procedures in 1994 to 8.1 % in 2003 [27]. While angiography was once strictly used for diagnostic purposes, the advent of stent grafts and coil embolization techniques has helped transform angiography into a therapeutic modality. Often, select catheter-based endovascular techniques are associated with decreased morbidity and mortality compared with open vascular reconstructive procedures. Endovascular interventions have been shown to decrease operating room times, blood losses, and iatrogenic injuries. The primary disadvantage of endovascular technology is the need to call in dedicated teams, the need for operating rooms or angiography suites adapted for endovascular interventions, and the need for hospital personnel with sufficient experience. Associated costs can vary depending on the institution. Failure of endovascular repair often revolves around the inability to cross the lesion with a wire. A relative contraindication is uncontrolled hemorrhage and hemodynamic instability, although this holds true only in the setting of an operating room not equipped to employ prompt and effective endovascular control of an injury. Other relative contraindications include the inability to use systemic anticoagulation such as multisystem trauma or closed-head injuries. Additional limitations include the possible need to cover major arterial branches with stents and the need to place stents in areas of mobility such as the popliteal artery, common femoral artery, or axillary artery [27–29].

Patient selection is an important concept in choosing when endovascular therapy for traumatic vascular injuries may be most effective. Endovascular intervention is best suited for difficult anatomic areas where obtaining operative exposure prolongs operating or ischemic time or increases the risk of bleeding. Additionally, if the anatomic region carries a risk of iatrogenic nerve injury, such as injuries involving the subclavian artery or internal carotid artery, endovascular therapies can eliminate the need to dissect in those areas [29]. Low-velocity penetrating traumatic injuries are the most easily repaired with endovascular techniques. Conversely, high-velocity, large cavitating injuries cause more damaging injuries and typically pose a need for definitive open repair due to associated contamination requiring debridement, fasciotomy for compartment syndrome, or embolectomy. Alternatively, larger injuries can be approached with proximal balloon occlusion to control hemorrhage and decrease blood loss during open exposure for definitive repair. Active hemorrhage from smaller, noncritical arteries can be embolized to permanently occlude bleeding. Perhaps the most widely accepted use of endovascular intervention is in single-vessel injuries below the trifurcation, where anterior tibial or tibioperoneal injuries are simply embolized, with no repair required [28–30].

Associated vascular injuries have also been managed with endovascular techniques. Pseudoaneurysms and arteriovenous fistulas caused by traumatic injury to vessels have been successfully treated both with the use of covered stents and coil embolization [31]. For fistulas, coils are deployed to occlude the arterial side, usually by isolating the fistula with proximal and distal coils. When utilizing coils, it is important to approximate the coil size to the diameter of the artery being embolized, as inappropriately sized coils have the potential to dislodge and embolize elsewhere. Dissections have also been treated with balloon dilation and stenting [3, 32].

Endovascular therapies are also being employed as temporary measures to control hemorrhaging vascular injuries in the event of other life-threatening injuries that require prompt attention by the trauma team prior to definitive repair of vasculature [32]. One such adjunct to primary trauma resuscitation is the development of resuscitative endovascular balloon occlusion of the aorta, or REBOA, which is a technique that provides the physiological benefit of aortic occlusion without the morbidity of emergency thoracotomy and aortic cross clamping. This technique was initially described as early as the 1950s during the Korean War; however, its use has been limited secondary to lack of skill set and/or concern over the ineffectiveness of the technique. Now with the advent of endovascular training courses for trauma surgeons that teach even the most basic of skill sets, REBOA is being revisited as a feasible and effective manner of aortic control in patients that present in profound hemorrhagic shock [33].

In the case of an actively hemorrhaging traumatic extremity injury, the patient should be brought to the operating room promptly. Since the need for prosthetic grafting is a possibility, typically antibiotics with gram-positive coverage are administered to protect against skin flora; however, antibiotics with additional gram-negative coverage may be given if there is concern for bony injury and need for manipulation or hardware. For planning purposes, the entire injured extremity should be prepped and draped, and an uninjured extremity should be included in the operative field in the event that autologous vein needs to be harvested for grafting. Vein harvesting is avoided in the injured extremity to prevent further venous injury and worsened postoperative swelling.