Vascular Surgery in the Austere Environment





Key Words:

vascular trauma , austere setting , resources , logistics , military , nongovernmental , team

 




Introduction


Vascular surgery is normally conducted in a highly technical environment with a full complement of specialized equipment including noninvasive ultrasound technology, state-of-the-art computed tomography (CT), modern fluoroscopy, specialized instruments for open surgery, and postoperative intensive care units and wards staffed with experienced vascular nurses and junior doctors. Performing vascular surgery in an austere environment is the antithesis to this. Faced with major vascular injury, the surgeon will find few tasks more demanding of his or her wisdom, especially with regard to decision making. The primary principles are always control of life-threatening hemorrhage and prevention of end-organ ischemia. However, time, resources, and the patient’s physiology are pressing factors that require constant consideration. The diagnosis and management of arterial and venous injury are performed by careful clinical examination supplemented with a continuous-wave Doppler probe. In the austere setting, there are rarely other, more-elaborate diagnostic modalities. Correct clinical decisions are paramount with limited equipment, inexperienced intensive care staff, and a limited means to transfer patients to a higher level of care.


It is vitally important to begin the task with the right mindset and to approach all vascular injuries in damage control mode. Blood loss alone will have altered the patient’s physiology, and the overriding necessities are to stop bleeding, to reestablish blood flow using shunts combined with fasciotomy or to ligate; and, if necessary, to perform amputation. One must also be prepared to make quick decisions. This is not the environment in which to spend a long time performing extensive and difficult vascular reconstructions. In general, one should not entertain the idea of performing a complex vascular anastomosis at the first operation. If the decision is to shunt the injured vessel, one must make sure all the bleeding has stopped and bring the patient back the following day for a more definitive operation. That strategy will allow time for the patient to warm up, will allow for adequate resuscitation to take place, and will allow time to source blood donors if blood is still required.


The single surgeon working in a relief or humanitarian aid scenario requires a multiplicity of skills. Apart from knowledge pertaining to vascular anatomy and surgical techniques, including extraanatomic bypass, it is also necessary to be able to perform nerve and tendon repairs, to undertake orthopedic trauma management (reduction of fractures, external fixation), and to be able to perform elements of plastic surgery (which entails knowledge of the blood supply to muscles and skin necessary to cover vascular repairs). The aim of this chapter is to review the management of the patient with vascular and associated injuries from the perspective of marked resource constraint and to highlight areas of differences and commonality with trauma surgery as it is practiced in replete, developed-world settings.




Fundamentals


Figure 23-1 demonstrates much of the basic equipment that should be taken on austere missions in which extensive injury management is anticipated. A handheld Doppler machine, magnifying loops, an operating headlight with batteries, 20 or so umbilical vein catheters (size 4 and size 6), and 4 boxes of 5-0 Prolene. Most nongovernmental organization (NGO) operating theaters are well provisioned, but lighting is usually a limitation, and the instruments tend to be fairly large and cumbersome.




FIGURE 23-1


Important tools for the austere vascular surgeon.


In general, clinical evidence of an arterial injury is manifested in one of the following four ways: external bleeding, end-organ or extremity ischemia, pulsatile hematoma, or internal bleeding accompanied by signs of shock. Patients present very early, early, late, or very late. Those who present late are a self-selected group, often hemodynamically normal but with mummified limbs (if in hot, dry climates). In this scenario, there is no role for revascularization; and amputation is the necessary option ( Fig. 23-2 ).




FIGURE 23-2


A 14-year-old girl who fell off a tree while picking mangos in Chad and presented to the hospital 2 weeks later.


Sometimes the patient may not understand the consequences of an arterial injury, therefore, making the rational argument for the amputation in order to save the patient’s life can be extremely challenging. The patient in Figure 23-3 did not appreciate that his leg was beyond salvage. When he did agree to an amputation 4 days later, he consented only to a below-knee amputation (though the whole of the below-knee compartment was necrotic). It took another week of intense discussion before the patient agreed to the definitive procedure, and by that time sepsis was present. In these instances, even if the patient understands that a limb is not viable, culture and religion sometimes decree that a person must die with his/her body in toto or intact. In such difficult circumstances, the surgeon must rely on his or her understanding and empathy for the patient’s personal and religious beliefs. The patient in South Sudan in Figure 23-4 was otherwise very fit and well, but he chose to return to his village with a wooden splint and died 2 weeks later.




FIGURE 23-3


Discussions pertinent to the level of amputation.



FIGURE 23-4


This patient had absent distal Doppler pulses due to a gunshot wound to the leg and refused treatment on religious grounds.


As highlighted in Chapter 5 , the decision to operate on vascular trauma is based on hard and soft signs of injury. Hard signs of vascular injury include the absence of distal pulses, active external hemorrhage, signs of ischemia, expanding or pulsatile hematoma, and a bruit or thrill (in the case of an arteriovenous fistula). Soft signs of vascular injury consist of a stable hematoma, diminished distal pulses, injury in the proximity of a major vessel, or neurological deficit. The most common arterial injury associated with hard signs is either a partial laceration or a complete vessel transection. In general, complete transection leads to retraction and thrombosis of the proximal and distal ends of the vessel with subsequent ischemia. In contrast, partial laceration causes persistent bleeding or pseudoaneurysm formation. In the austere environment, only those patients with hard signs undergo treatment. The diagnostic equipment is generally not available to accurately diagnose vascular injury presenting only with soft signs. Repeat examinations or serial clinical monitoring and pressure measurements (i.e., injured extremity index [IEI]) with the handheld Doppler will often reveal a trend in patients who initially present with soft signs and then go on to develop hard signs.




Neck Injuries


Carotid Injuries


In austere environments, the only indication for surgery in the neck is penetrating trauma with hard signs. Blunt carotid injuries resulting in intimal disruption with subsequent dissection or thrombosis may present with catastrophic neurological symptoms that develop sometime after the injury was sustained. Such patients do not normally present to the surgeon. In cases of penetrating trauma, the method of exposure and treatment of injuries to the vascular structures of the neck is determined in large part by the precise location of the injury and the anatomy of blood vessels and surrounding structures. The neck has been classically been divided into three zones ( Fig. 23-5 ). Zone I is from below the cricoid cartridge to the superior border of the clavicle; zone II lies between the cricoid cartilage and the angle of the jaw; zone III extends above the angle of the jaw to the base of the skull. Hard signs include external or intraoral bleeding, an expanding (arterial) or stable (venous) hematoma, stridor and air bubbling from the wound, and a palpable thrill or audible bruit. In the absence of hard signs, assessment of the neck is by careful clinical examination, which must be repeated serially. Without clinical signs of a vascular- or aerodigestive injury (such as pain on swallowing, subcutaneous emphysema, or soft tissue air on a lateral neck radiograph), nonoperative management should be followed. If facilities for a barium/Gastrografin swallow are available, that should be performed. Nonoperative management does not equate with conservative management, and these patients should be regularly reviewed. Any change in status may mean a change in the management plan is needed. There has been considerable debate in the literature regarding whether it is mandatory to explore any wound in the neck that has penetrated the platysma. This author’s policy is to not explore the neck in the absence of hard signs.




FIGURE 23-5


Zones of the neck.

(Redrawn from Penetrating neck injuries. Oral Maxillofacial Surg Clin N Am 20:393–414, 2008.)


If bleeding is coming from the external carotid artery or its branches, ligation is the preferred option. An injury to the common carotid artery below the bulb, if deemed unreconstructible, can be managed with ligation. In these challenging cases, one must accept that perfusion of the brain on the injured side will occur via retrograde flow from the posterior circulation and the contralateral side. Other injuries of the bulb and internal carotid artery can be reconstructed with a vein patch and segmental defects managed with an interposition vein graft. In all cases, the long saphenous vein should be harvested from the groin because there are reports of carotid patch disruption if the vein is taken from the ankle. Resection of the internal carotid with external-to-internal carotid artery transposition is a good option when treating proximal internal carotid artery (ICA) injuries in children. Injuries involving the jugular veins can be ligated with impunity, and this is the preferred option over reconstruction in the austere setting.


There has been debate about the use of a cervical collar in penetrating neck injuries. In the author’s opinion most patients with penetrating neck injuries will not survive if they have cervical spine trauma because they are already tetraplegic or have associated major head injury. Those with no neurological signs rarely have a spinal injury, so using a collar may potentially obstruct the airway and mask other injuries.


The patient with a hard sign or signs of cervical vascular trauma should be taken urgently to the operating theater, because rapid expansion of a hematoma may occur, resulting in deviation of the trachea and elevation of the floor of the mouth. In this circumstance, one must be prepared to perform an emergency tracheostomy or cricothyroidotomy if the anesthetist is having any difficulty with intubation. One must also be sure to prep the neck and chest, in case of the requirement for proximal control, and to prep the proximal thigh for vein harvesting ( Fig. 23-6 ). If needed, suction drains can easily be made by creating a vacuum in a 50-mL syringe and then using plungers from 20-mL syringes to maintain the plunger in the suction position ( Fig. 23-7 ).




FIGURE 23-6


Tetraplegic patient with a low-velocity gunshot wound to the side of the face, causing external carotid artery and internal jugular vein disruption. Both the artery and the vein were ligated.



FIGURE 23-7


Syringe suction bottle.


Preoperatively, it is very important to assess the neurological status of the patient using the Glasgow Coma Scale (GCS). An adverse outcome is more likely to occur in a patient with a GCS of less than 8, and in this situation the ICA should be ligated if it is found to be the cause of the bleeding. In this scenario, no attempt at carotid repair should be made, even if there is antegrade flow, due to the risks of causing propagation of thrombus and, on restoration of perfusion, converting an ischemic infarct into a hemorrhagic one. Those not in coma or with only a mild neurological deficit should be considered for carotid repair using a vein patch or reversed vein. Because only 35% of patients have an intact circle of Willis, there is a risk of significant neurological insult if the ICA is ligated.


Carotid—jugular fistulae are rare. In 1994, during this author’s mission to Sarajevo, a 13-year-old girl with a fragment wound to the neck presented for care. The penetrating wound had become swollen, and there was a readily palpable thrill over the enlarged neck mass. Unlike arteriovenous fistulae in the limbs, carotid–jugular fistulae are particularly prone to complications such as intractable high-output cardiac failure, atrial fibrillation, and embolization. In the case of the 13-year-old girl, the common carotid artery was clamped; and perfusion of the internal carotid relied on flow from the external carotid. Having isolated the fistula, both the internal jugular vein and the common carotid artery were repaired with 5-0 Prolene.


It is recognized that internal carotid artery stump pressures are highly variable; but, on the whole, the ICA back pressure may be augmented by 10 mm Hg to 15 mm Hg if the external carotid artery is maintained in continuity. If this can be maintained, it may augment internal carotid artery stump pressures to the degree that repair of some carotid injuries may not be necessary. Although some surgeons advocate using a shunt in isolated common carotid artery injuries, this author has not used one in this situation; and there are no studies to support its role in this setting.


Associated Neck Injuries


In the setting of penetrating neck wounds with a vascular component, one should always look for injuries to the esophagus and the laryngotrachea. If preoperative radiology is not possible, one can ask the anesthetist to pass a nasogastric tube to allow easier identification of the esophagus. Repair of local damage to the esophagus may be undertaken with a two-layered 3-0 absorbable suture, using the sternomastoid muscle to buttress the suture line and to reduce the risk of leakage. This muscle takes its blood supply from the occipital artery and the superior thyroid artery branches of the thyrocervical trunk and thus can be mobilized from the clavicle by dividing the sternal and clavicular heads. Tracheal injuries can be repaired primarily with an absorbable suture and similarly buttressed with the sternomastoid muscle. If the tracheal defect is large, it should be converted into a tracheostomy.


Operative Management of Zone III Injuries


Various techniques for gaining access to the inherently difficult-to-expose distal internal carotid artery have been reported. However, methods involving subluxation of the temporomandibular joint and vertical ramus osteotomy are often not achievable in the austere environment. A useful technique is to divide the digastric muscle and to partially sublux the mandibular condyle. This is accomplished by forceful opening of the mouth, kept open by careful positioning of a self-retaining retractor with swabs over the molars and a Langenbeck retractor placed under the angle of the jaw to lift it forward. This was the technique used in one such case that is depicted in Figure 23-8 .




FIGURE 23-8


Zone III injury of the carotid, with the defect repaired with a vein patch.


Operative Management of Zone I Injuries


The classic teaching for zone I injuries of the neck is that proximal control of the innominate, the subclavian, and the carotid arteries should be enabled via a median sternotomy, followed by cervical extension into either side of the neck ( Fig. 23-9 ). In the austere environment, this approach has to be tempered with the available resources for preoperative and postoperative care. In some circumstances, appropriate facilities are available, and in these cases a median sternotomy is the best option. If the necessary equipment is available, this exposure is not difficult to perform and provides an excellent working view of zone I vascular structures.




FIGURE 23-9


Pulsatile swelling in zone I and zone II of the neck due to a gunshot wound with median sternotomy to gain proximal control of the carotid artery.


If conditions are not suitable to perform a median sternotomy, one should consider taking the clavicle out in order to gain access to the root of the neck. This is performed by making a supraclavicular incision extending from the midline, coursing over the midpoint of the clavicle, and continuing below the clavicle to the deltopectoral groove. The sternal and clavicular heads of the sternomastoid muscle are divided, and a periosteal elevator is used to separate the structures over the clavicle. It is easier to divide the clavicle with bone cutters than to dislocate it from the acromioclavicular and sternoclavicular joints. Following separation from the underlying subclavius muscle, divide the scalenus anterior while preserving the phrenic nerve. This gives excellent access to the whole of the first part of the subclavian artery, the proximal common carotid, and the axillary vessels. Contrary to opinion, the shoulder is not destabilized by its removal, provided the muscles attached to it are reconstituted.


The left side may be more difficult to expose because the subclavian artery arises posteriorly from the aortic arch, but gentle traction on the first part with a Satinsky clamp often yields an additional centimeter of length. This must be performed with care as the subclavian artery is thin and nonmuscular, and it tears easily. If the subclavian artery is torn during access maneuvers, the first task should be to ligate the vessel rather than to try to repair it. In most cases, upper limb circulation is maintained via the rich collateral circulation around the shoulder girdle ( Fig. 23-10 ).




FIGURE 23-10


Gunshot to zone I of the neck with removal of the clavicle and ligation of the subclavian artery.


An alternative to full sternotomy is limited sternotomy, which can be performed using bone cutters to divide the manubrium to the level of the sternomanubrial joint giving access to the upper mediastinum. In this author’s view, one should avoid the trapdoor incision and exposure (which includes an anterior left thoracotomy and median sternotomy through the third or fourth interspace), because this is associated with the following: significant bleeding (resulting from the division of thick muscles); severe postoperative pain (due to iatrogenic rib fractures); and a high incidence of respiratory complications. If it is not possible to perform a limited sternotomy, one should consider an anterolateral thoracotomy with extension to the other chest (i.e., a clamshell incision), which provides excellent exposure. Postoperative ventilation may be promoted through aggressive analgesia, including intercostal nerve blocks, and early physiotherapy.




Carotid Injuries


In austere environments, the only indication for surgery in the neck is penetrating trauma with hard signs. Blunt carotid injuries resulting in intimal disruption with subsequent dissection or thrombosis may present with catastrophic neurological symptoms that develop sometime after the injury was sustained. Such patients do not normally present to the surgeon. In cases of penetrating trauma, the method of exposure and treatment of injuries to the vascular structures of the neck is determined in large part by the precise location of the injury and the anatomy of blood vessels and surrounding structures. The neck has been classically been divided into three zones ( Fig. 23-5 ). Zone I is from below the cricoid cartridge to the superior border of the clavicle; zone II lies between the cricoid cartilage and the angle of the jaw; zone III extends above the angle of the jaw to the base of the skull. Hard signs include external or intraoral bleeding, an expanding (arterial) or stable (venous) hematoma, stridor and air bubbling from the wound, and a palpable thrill or audible bruit. In the absence of hard signs, assessment of the neck is by careful clinical examination, which must be repeated serially. Without clinical signs of a vascular- or aerodigestive injury (such as pain on swallowing, subcutaneous emphysema, or soft tissue air on a lateral neck radiograph), nonoperative management should be followed. If facilities for a barium/Gastrografin swallow are available, that should be performed. Nonoperative management does not equate with conservative management, and these patients should be regularly reviewed. Any change in status may mean a change in the management plan is needed. There has been considerable debate in the literature regarding whether it is mandatory to explore any wound in the neck that has penetrated the platysma. This author’s policy is to not explore the neck in the absence of hard signs.




FIGURE 23-5


Zones of the neck.

(Redrawn from Penetrating neck injuries. Oral Maxillofacial Surg Clin N Am 20:393–414, 2008.)


If bleeding is coming from the external carotid artery or its branches, ligation is the preferred option. An injury to the common carotid artery below the bulb, if deemed unreconstructible, can be managed with ligation. In these challenging cases, one must accept that perfusion of the brain on the injured side will occur via retrograde flow from the posterior circulation and the contralateral side. Other injuries of the bulb and internal carotid artery can be reconstructed with a vein patch and segmental defects managed with an interposition vein graft. In all cases, the long saphenous vein should be harvested from the groin because there are reports of carotid patch disruption if the vein is taken from the ankle. Resection of the internal carotid with external-to-internal carotid artery transposition is a good option when treating proximal internal carotid artery (ICA) injuries in children. Injuries involving the jugular veins can be ligated with impunity, and this is the preferred option over reconstruction in the austere setting.


There has been debate about the use of a cervical collar in penetrating neck injuries. In the author’s opinion most patients with penetrating neck injuries will not survive if they have cervical spine trauma because they are already tetraplegic or have associated major head injury. Those with no neurological signs rarely have a spinal injury, so using a collar may potentially obstruct the airway and mask other injuries.


The patient with a hard sign or signs of cervical vascular trauma should be taken urgently to the operating theater, because rapid expansion of a hematoma may occur, resulting in deviation of the trachea and elevation of the floor of the mouth. In this circumstance, one must be prepared to perform an emergency tracheostomy or cricothyroidotomy if the anesthetist is having any difficulty with intubation. One must also be sure to prep the neck and chest, in case of the requirement for proximal control, and to prep the proximal thigh for vein harvesting ( Fig. 23-6 ). If needed, suction drains can easily be made by creating a vacuum in a 50-mL syringe and then using plungers from 20-mL syringes to maintain the plunger in the suction position ( Fig. 23-7 ).




FIGURE 23-6


Tetraplegic patient with a low-velocity gunshot wound to the side of the face, causing external carotid artery and internal jugular vein disruption. Both the artery and the vein were ligated.



FIGURE 23-7


Syringe suction bottle.


Preoperatively, it is very important to assess the neurological status of the patient using the Glasgow Coma Scale (GCS). An adverse outcome is more likely to occur in a patient with a GCS of less than 8, and in this situation the ICA should be ligated if it is found to be the cause of the bleeding. In this scenario, no attempt at carotid repair should be made, even if there is antegrade flow, due to the risks of causing propagation of thrombus and, on restoration of perfusion, converting an ischemic infarct into a hemorrhagic one. Those not in coma or with only a mild neurological deficit should be considered for carotid repair using a vein patch or reversed vein. Because only 35% of patients have an intact circle of Willis, there is a risk of significant neurological insult if the ICA is ligated.


Carotid—jugular fistulae are rare. In 1994, during this author’s mission to Sarajevo, a 13-year-old girl with a fragment wound to the neck presented for care. The penetrating wound had become swollen, and there was a readily palpable thrill over the enlarged neck mass. Unlike arteriovenous fistulae in the limbs, carotid–jugular fistulae are particularly prone to complications such as intractable high-output cardiac failure, atrial fibrillation, and embolization. In the case of the 13-year-old girl, the common carotid artery was clamped; and perfusion of the internal carotid relied on flow from the external carotid. Having isolated the fistula, both the internal jugular vein and the common carotid artery were repaired with 5-0 Prolene.


It is recognized that internal carotid artery stump pressures are highly variable; but, on the whole, the ICA back pressure may be augmented by 10 mm Hg to 15 mm Hg if the external carotid artery is maintained in continuity. If this can be maintained, it may augment internal carotid artery stump pressures to the degree that repair of some carotid injuries may not be necessary. Although some surgeons advocate using a shunt in isolated common carotid artery injuries, this author has not used one in this situation; and there are no studies to support its role in this setting.




Associated Neck Injuries


In the setting of penetrating neck wounds with a vascular component, one should always look for injuries to the esophagus and the laryngotrachea. If preoperative radiology is not possible, one can ask the anesthetist to pass a nasogastric tube to allow easier identification of the esophagus. Repair of local damage to the esophagus may be undertaken with a two-layered 3-0 absorbable suture, using the sternomastoid muscle to buttress the suture line and to reduce the risk of leakage. This muscle takes its blood supply from the occipital artery and the superior thyroid artery branches of the thyrocervical trunk and thus can be mobilized from the clavicle by dividing the sternal and clavicular heads. Tracheal injuries can be repaired primarily with an absorbable suture and similarly buttressed with the sternomastoid muscle. If the tracheal defect is large, it should be converted into a tracheostomy.




Operative Management of Zone III Injuries


Various techniques for gaining access to the inherently difficult-to-expose distal internal carotid artery have been reported. However, methods involving subluxation of the temporomandibular joint and vertical ramus osteotomy are often not achievable in the austere environment. A useful technique is to divide the digastric muscle and to partially sublux the mandibular condyle. This is accomplished by forceful opening of the mouth, kept open by careful positioning of a self-retaining retractor with swabs over the molars and a Langenbeck retractor placed under the angle of the jaw to lift it forward. This was the technique used in one such case that is depicted in Figure 23-8 .




FIGURE 23-8


Zone III injury of the carotid, with the defect repaired with a vein patch.




Operative Management of Zone I Injuries


The classic teaching for zone I injuries of the neck is that proximal control of the innominate, the subclavian, and the carotid arteries should be enabled via a median sternotomy, followed by cervical extension into either side of the neck ( Fig. 23-9 ). In the austere environment, this approach has to be tempered with the available resources for preoperative and postoperative care. In some circumstances, appropriate facilities are available, and in these cases a median sternotomy is the best option. If the necessary equipment is available, this exposure is not difficult to perform and provides an excellent working view of zone I vascular structures.




FIGURE 23-9


Pulsatile swelling in zone I and zone II of the neck due to a gunshot wound with median sternotomy to gain proximal control of the carotid artery.


If conditions are not suitable to perform a median sternotomy, one should consider taking the clavicle out in order to gain access to the root of the neck. This is performed by making a supraclavicular incision extending from the midline, coursing over the midpoint of the clavicle, and continuing below the clavicle to the deltopectoral groove. The sternal and clavicular heads of the sternomastoid muscle are divided, and a periosteal elevator is used to separate the structures over the clavicle. It is easier to divide the clavicle with bone cutters than to dislocate it from the acromioclavicular and sternoclavicular joints. Following separation from the underlying subclavius muscle, divide the scalenus anterior while preserving the phrenic nerve. This gives excellent access to the whole of the first part of the subclavian artery, the proximal common carotid, and the axillary vessels. Contrary to opinion, the shoulder is not destabilized by its removal, provided the muscles attached to it are reconstituted.


The left side may be more difficult to expose because the subclavian artery arises posteriorly from the aortic arch, but gentle traction on the first part with a Satinsky clamp often yields an additional centimeter of length. This must be performed with care as the subclavian artery is thin and nonmuscular, and it tears easily. If the subclavian artery is torn during access maneuvers, the first task should be to ligate the vessel rather than to try to repair it. In most cases, upper limb circulation is maintained via the rich collateral circulation around the shoulder girdle ( Fig. 23-10 ).




FIGURE 23-10


Gunshot to zone I of the neck with removal of the clavicle and ligation of the subclavian artery.


An alternative to full sternotomy is limited sternotomy, which can be performed using bone cutters to divide the manubrium to the level of the sternomanubrial joint giving access to the upper mediastinum. In this author’s view, one should avoid the trapdoor incision and exposure (which includes an anterior left thoracotomy and median sternotomy through the third or fourth interspace), because this is associated with the following: significant bleeding (resulting from the division of thick muscles); severe postoperative pain (due to iatrogenic rib fractures); and a high incidence of respiratory complications. If it is not possible to perform a limited sternotomy, one should consider an anterolateral thoracotomy with extension to the other chest (i.e., a clamshell incision), which provides excellent exposure. Postoperative ventilation may be promoted through aggressive analgesia, including intercostal nerve blocks, and early physiotherapy.

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Oct 11, 2019 | Posted by in CARDIOLOGY | Comments Off on Vascular Surgery in the Austere Environment
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