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VASCULAR TRAUMA
DAMAGE CONTROL

 

 

Peripheral Vascular Trauma
Karim Brohi, trauma.org 7:3, March 2002

Management

The priorities of vascular injury are arrest of haemorrhage and restoration of normal circulation.

Airway control and respiratory assessment take priority over management of the circulation, but these can often be achieved in tandem when there is a trauma team in attendance.

 

Vascular Trauma Basics

Introduction
Pathophysiology
Diagnosis
Management
References

Immediate Haemorrhage Control
Immediate control is usually achievable by direct pressure over the site of injury. This pressure does not need to be great (Systolic blood pressure is around 100mmHg), but it does need to be directed over the site of haemorrhage. Large bandages and pads applied overwounds, with more and more bandaging applied as the bandages soak with blood, is not controlling haemorrhage! It is better to dedicaton one individual to manually compress the site of haemorrhage.

Where haemorrhage is welling up from a deep knif or gunshot track, control may be temporarily achieved by passing a urinary catheter into the track as far as possible, inflating the balloon, and then applying traction to the catheter. The catheter can be sutured in place if the patient is to be transferred to another department or hospital.

If angiography is performed prior to surgery, it may be possible to obtain proximal control by passing an angioplasty balloon catheter into the proximal vessel and inflating the balloon. This can also aid dissection of the vessel at operation, as the angioplasty balloon is easily palpable within the haematoma. The radiology suite should not be used for proximal control alone - this is more appropriately performed surgically in the operating room.

Blind clamping in the depths of a wound is dangerous, likely to fail, and likely to injure other structures.

Volume resuscitation
There are two phases in the resuscitation of patients with vascular injuries - before and after haemorrhage control. Prior to haemorrhage control, minimal fluids should be administered. Raising the blood pressure will increase haemorrhage from the vessel injury and dislodge any clot that has already formed. The patient cools as more cold fluids are administered. Clotting factors are used up and diluted, and the patients become coagulopathic. Shock worsens, heat production is impaired and clotting enzyme activity is attenuated.

The priority in this phase is operative control of haemorrhage and there should be no delay in transferring the patient. Systolic blood pressure can be maintained at a level that is appropriate for perfusion of the brain. If the patient is talking and orientated, the blood pressure is adequate, regardless of actual value. For unconscious patients, a sysolic of 60-70mmHg is adequate in the absence of significant brain injury. No inotropes should be given to the hypovolaemic patient as this will effectively deplete myocardial tissue oxygen and increase myocardial work in the absence of adequate preload. These patients are already maximally vasoconstricted.

Large bore venous access is necessary however, and there should be at least two sites of access to the circulation, appropriate for giving warmed fluids rapidly. Once haemorrhage control is achieved, there is a phase of aggressive volume resuscitation to restore circulating blood volume. Warmed fluids -crystalloid, blood or clotting factors as necessary -are administered to correct acidosis, hypothermia and coagulopathy, and to restore perfusion rapidly to shut-down organ systems. This should help to prevent the subsequent development of a systemic inflammatory response and its consequences.

Operative Strategy
The patient is positioned on the operating table to allow on-table angiography of the affected region and distal perfusion. The entire affected limb is prepped and draped, as well as proximal structures if control has to be gained more proximally. The hand or foot is prepped so that intra-operative assessment of distal perfusion is possible. An entire uninjured limb should also be prepped so that a vein graft can be harvested as required. Often the person applying manual compression at a bleeding site will have to be temporarily prepped into the operative field until scrubbed personnel can take over.

The basic principle of vascular repair is to gain proximal and distal control of the relevant vessel before investigating the site of injury. Direct exploration of a wound that is actively bleeding will inevitably lead to failure to control the haemorrhage and collateral damage to neighbouring structures. Proximal control is best achieved through a separate incision away from the site of injury. Distal control similarly is best achieved via a second incision. Once proximal and distal control is achieved, the site of injury can be explored and control made closer to the injury site. It may be tempting to directly explore a wound that is not actively bleeding. However, profuse haemorrhage can rapidly obscure the operative field once clot is dislodged from around the site of vascular injury.

Control is best achieved with slings passed twice around the vessel. If vascular clamps are used they should be applied with the minimum force necessary to obstruct flow, not racked closed causing vessel wall damage. Do not attempt to encircle the aorta or iliac arteries for risk of damage to lumbar arteries or iliac veins.

Once the vessel injury is identified, a decision on repair technique must be made. This will depend on the extent of damage to the vessel. The first step is therefore debridement of devitalised tissue and definition of the edges of the wound. Next an assessment of inflow and outflow is made. If it is inadequate, a balloon (Fogarty) catheter is passed proximally and distally to extract any thrombus. Following extraction, heparinized saline is instilled proximally and distally to locally antcoagulate the vessel.

Small, clean, transverse wounds to vessels that involve only part of the circumference can be repaired with a direct suture technique. A vein (or synthetic) patch may be required where there is a larger defect in the vessel wall where direct sutuing may lead to narrowing of the vessel lumen. While vein grafts probably have a longer patency, the graft infection rates are the same for both vein and synthetic grafts, regardless of wound contamination.

 
Vein patch to carotid artery

The ends of a transected artery usually retract. If the ends can be approximated without tension, a direct end-to-end anastomosis repair can be employed. Mobilisation of the two ends may be necessary, and aided by division of minor arterial branches.

 
End-to-end anastomosis of transected popliteal artery.

Where approximation of the vessels is not possible, a reversed vein graft, or synthetic graft is used to repair the defect. If there is a concomitant vein injury, this should usually be repaired first, if possible to avoid low-flow thrombosis of the arterial repair.

 
Reversed vein graft to transected common femoral artery.

Intra-operative angiography
Intra-operative angiography is indicated if the location of the vascular injury is unknown, if distal perfusion is inadequate after a vascular repair is completed, or at the end of a procedure for completion angiography.

To perform an angiogram, proximal control is attained. This prevents flushing away of contrast and makes timing of injection much easier. A small arteriotomy is made to allow the introduction of an 18 guage catheter. A 50/50 dilution of intravenous contrast is used. An initial scout film can be taken, and then 20 to 50 mls of contrast solution injected rapidly, and the arteriogram film obtained. A delay of 10 to 15 seconds should be used where distal vessels are being imaged. If there is any doubt about the timing of the image, a second film can be taken. Fluoroscopy and digital subtraction angiography avoid many of the pitfalls associated with plain film radiographjy in the operating room.

Damage Control
The principles of damage control surgery can be applied to vascular trauma. The basic damage control techniques are ligation and shunting.

Ligation
There are very few vessels that cannot be ligated in extremis, at varying risk to life and limb. The common and external carotid, subclavian, axillary, internal iliac can be ligated with few consequences. Ligation of the internal carotid artery carries a 10-20% risk of stroke. Ligation of the exteral iliac artery, common femoral or superficial femoral have a signficant risk of critical limb ischaemia following ligation. Ischaemia is more likely if there is significant soft tissue injury and distruction of supporting collateral circulation. Arteries of the celiac axis can be ligated but ligation of the superior or inferior mesenteric artery will almost inevitably lead to gut necrosis in the young trauma patient.

Almost all veins, including the inferior vena cava, can be ligated where necessary, with the consequence of lower limb oedema. Ligation of the portal vein is possible but bowel oedema with massive 'third-space' fluid losses will ensue..

Shunting
Where there is a significant risk of limb loss, stroke, gut ischaemia or other serios consequence of ligation, intraluminal shunts may be employed to temporarily restore flow. While specific vascular shunts are available, shunts can be rapidly constructed out of sterile intravenous tubing or chest tubes for larger calibre vessels. Ensure that shunts are secured in place so that they do not become dislodged during transfer to the intensive care unit or during nursing procedures.

Where there is a vascular injury associated with a fracture, and there is a risk of orthopaedic manoeuvers disrupting an arterial repair, shunts may be employed to temporarily restore flow to an injured limb. Definitive repair is then carried out after fracture fixation. Shunts may also be used while assessing an amputated limb for its viability for reimplantation.


Superficial Femoral Artery injury following impalement
(Classic Case 013)

Compartment syndrome
Prolonged interruprion of blood flow to a limb leads to cellular ischaemia, actibvation of cellular and humoral inflammatory responses and alterations in vascular permeability. Subsequent reperfusion of the limb leads to generalised tissue oedema. When this occurs in a limited, enclosed space - such as the fascial compartments of the lower limb, the pressure in the compartment may rise above capillary and venous pressure and cause vascular stasis, cellular ischaemia and death.

The pressure in the compartments is rarely above arterial pressure and distal pulses are preserved. If the patient is awake, there is intense, disporoportionate pain in the limb, worsened by passive flexion of the muscle groups. Many patients are unconscious, have spinal cord injury or epidural anaesthesia. In this case the early, reversible signs of compartment syndrome may be lost and diagnosis relies on a high index of suspicion and measurement of compartment pressures. Values over 30mmHg are diagnostic of compartment syndrome.

Prevention is better than cure and the aphorism 'If you think about doing a fasciotomy, you should do one' probably still holds true. Fasciotomy is best performed at the time of initial surgery, rather than as a subsequent procedure for a second episode of limb ischaemia. Compartment syndrome is not confined to the distal lower extremity and can occur in the thigh, buttock and forearm.

 

 

References

trauma.org (7:3) March 2002