14.1  Commentary

Lower limb injuries, due to penetrating trauma, can be devastating and occasionally may distract the clinician from less obvious but potentially life-threatening injuries to the head, neck and torso. It is important that some form of resuscitation protocol is followed such as the ATLS system to detect less obvious injuries. Time is of the essence when managing vascular injuries. While delays rarely occur in patients with obvious haemorrhage, it is the prompt instigation of life-saving measures and ongoing diagnosis in parallel with transfer to the operating theatre for definitive care that reduces morbidity and mortality. [Q1: A, D]

The clinical manifestations of vascular injury have traditionally been divided into “hard” and “soft” signs (Table 14.1). [Q2: B, E]

In general, preoperative arteriography may be used in the following situations: (1) to confirm the site and extent of vascular injury in stable patients whose clinical signs and symptoms are equivocal; and (2) to exclude vascular injury in patients with no hard signs, but who are considered to be at risk because of the proximity of the injury. The majority of patients with penetrating extremity trauma and the presence of a single hard sign should be transferred directly to the operating theatre. Possible exceptions to this rule include stable patients with multiple levels of injury, extensive bone or soft tissue injury, blast or shotgun injuries, potential injuries to the subclavian or axillary arteries and the pre-existence of peripheral vascular disease. Some centres report excellent results with emergency room angiography1 while recent advances in endovascular technique facilitate high-quality imaging in the operating theatre. [Q3: B, C]

Inadequatetissueperfusionduetomajorvesseldisruptionisaggravatedbyhypovolemic shock and associated bone and soft tissue injury. The resulting fall in tissue pO2 increases capillary membrane permeability, with increased exudation of fluid into the interstitial space. Compromised muscle fibres swell within the fascial compartments, causing further resistance to blood flow, and swelling becomes traumatic when arterial repair and restoration of flow brings about reperfusion injury. The degree of reperfusion injury depends on the duration of ischaemia, and is mediated by the generation of free radicals, activation of neutrophils, and production of arachidonic acid metabolites. Eventually, the microvascular bed of the extremity may undergo widespread thrombosis.2 It is generally accepted that a warm ischaemia time of more than 6–8 h makes limb survival unlikely. [Q4: C] To achieve optimal results from emergency vascular repair, and to avoid complications

such as compartment syndrome or contracture due to prolonged warm ischaemia and reperfusion injury, surgical exploration should be undertaken expeditiously.

A patient with complex lower limb injuries should be placed in a supine position on an operating table suitable for on-table angiography, if required, when clinical stability has been reached. Some form of warming device should be employed to maintain adequate body temperature. In lower limb trauma, both limbs should be prepared from umbilicus to toes; donor saphenous vein harvesting may be required from the contralateral limb, particularly if ipsilateral venous injury is suspected. Careful attention should be given to correct hypothermia, blood loss, electrolyte imbalance and coagulopathy.

The principal aims of emergency vascular surgery are to control life-threatening haemorrhage and prevent end-organ ischaemia. [Q5: A, B] An assistant should control haemorrhage using a pressure dressing until the patient is prepared and draped appropriately. Haemorrhage control can be difficult if the proximal vessels are not immediately apparent, and the use of a cephalad incision through virgin territory may be a reasonable alternative to obtain rapid proximal control. Care should be taken when making additional incisions, particularly if it seems likely that plastic surgery will be required at a later date. When access to the proximal or distal vessel is difficult, temporary control can be gained by careful cannulation and inflation of an embolectomy catheter. It is important that the surgeon cooperates fully with the anaesthetist during surgery as it may be necessary to pack the wound for a few minutes to facilitate IV fluid resuscitation before proximal vascular control can be obtained. Complex lengthy operations should be avoided in unstable patients and damage limitation surgery should be considered in patients with significant metabolic acidosis, coagulopathy and/or hypothermia.

Theuseofatemporaryintraluminalvascularshuntshouldbeconsideredinthemajority of limb vascular injuries and is particularly important in complex cases with associated bone and soft tissue injury.

Temporary shunts for arterial and venous injuries have been employed in Belfast since the late 1970s.2 A considerable body of evidence continues to support the use of these intravascular shunts in the management of both penetrating and blunt major vascular trauma.3–6 Before securing the shunt between the proximal and distal arteries, a careful embolectomyshouldbeperformedtoremoveanythrombusinthedistalvessel.Ifavenous injury is encountered, then an additional shunt can be employed to facilitate venous return. In the absence of coagulopathy or ongoing haemorrhage we use IV heparin routinely. Recent evidence has shown clearly that delayed renewal of venous flow in combined arterial and venous injury compounds ischaemia-reperfusion injury and causes remote lung injury.7 The advantages of shunting artery and vein are the early restoration of blood flow and venous return, respectively, thus avoiding the complications of prolonged ischaemia and ischaemia-reperfusion injury while ensuring that an optimal vascular repair can be performed.

In patients with concomitant fractures, accurate internal or external fixation of the fracture can be performed with the shunt secured carefully with sloops before definitive vascular repair is performed. This avoids the dilemma of unnecessary haste for both the orthopaedic and vascular surgeons, ensures that a vein graft will be of optimal length, and eliminates the risk of graft disruption during fracture manipulation. Autologous vein is our preferred bypass conduit in the majority of cases because of its durability and suitability in

a potentially contaminated wound. Satisfactory results, however, have been reported using synthetic grafts and in critically ill, unstable patients this may be a preferable option.8

The acute management of high energy limb trauma can be challenging and significant morbidity and mortality can occur following failed attempts at limb salvage. A number of scoring systems have been devised in an attempt to assist the clinician’s decision to either amputate or perform a limb-salvage procedure.9–13 In each of the systems, a score is assigned based on a range of differing criteria including patient age, “mechanism of injury”, time to treatment, degree of shock, warm ischaemia time and the presence of local injuries to the following structures: major artery, major vein, bone, muscle, nerve, skin, and degree of contamination. [Q6: E] All of these scoring systems demonstrate a much higher degree of specificity than sensitivity and are more useful in highlighting the patients who should be considered for a limb-salvage procedure, than identifying those who should proceed straight to primary amputation. Indeed a number of studies have challenged their use at all.14,15

It is the authors’ opinion that scoring systems can help the surgeon perform a detailed assessment of a complex limb injury. However, the decision to perform a primary amputation must be judged individually in each case. Extensive nerve injuries have a particularly poor prognosis and it is important that such injuries, where possible, are documented before taking the patient to the operating theatre. The patient’s life should never be put at risk in a futile attempt to save a severely compromised limb. Where possible, additional specialties such as orthopaedics and plastic surgery should be involved in the decision to perform a primary limb amputation, particularly in a case of upper limb trauma.

Venous injuries can be difficult to manage. Prior to World War II, the traditional treatment for lower extremity venous injuries was ligation. This custom was challenged by Debakey and Simeone16 in 1946 with an analysis of WWII battle injuries. Since then a number of clinical and laboratory investigations have confirmed that ligation of major veins in conjunction with repair of a traumatically injured arterial system leads to significantly poorer clinical outcomes, such as decreased function or even limb loss.17,18 Where possible vein repair should be attempted, particularly in the presence of significant lower limb arterial injury, in an attempt to reduce venous hypertension and associated morbidity. While there are few data regarding the long-term outcome of venous repairs, it is the authors’ impression that maintaining venous patency, in the initial few days after injury, can significantly help reduce acute post-injury swelling. If the superficial femoral vein requires ligation, it is important to maintain patency of the ipsilateral long saphenous and profundafemorisveins.Complexveinrepairshouldneverbeattemptedinunstablepatients who have sustained major blood loss and have significant problems with hypothermia and coagulopathy. In more stable patients, however, temporary intraluminal venous shunting can facilitate the construction of larger calibre panel grafts obtained from the contralateral long saphenous vein. [Q7: D, E]

Postoperative management of patients with complex limb injuries is critically important. The majority of these patients have been transferred immediately to the operating theatre and it is important that a thorough search for occult injuries is performed on admission to the intensive care unit. These patients are at risk of developing multiple organ dysfunctionsyndromeasaresultoftheirlargetransfusionrequirementsandlikelyreperfusion injury sustained.19,20 It is important that the vascular surgeon communicates clearly

with the staff in the intensive care unit regarding the presence or absence of distal pulses, to ensure that vascular repair remains patent. Young trauma patients with normal blood pressure and temperature should have a palpable distal pulse. If there is any doubt regarding the integrity of the vascular repair, the dressings should be removed and a careful assessmentperformedbyavascularsurgeonusinghandheldDopplerand/orportableultrasound device.

Wounds should be reinspected 24–48 h after initial surgery and at that stage definitive plastic surgery may be required to obtain soft tissue and skin cover. [Q8: D] Some centres advocate a selective policy with regard to fasciotomy based on compartmental pressures, whilemanycontinuetoadvocateamoreliberalpolicybasedonclinicalgrounds.Prolonged ischaemia time, combined arteriovenous injuries, complex injuries including bone and soft tissuedestructionandcrushinjuriesremainabsoluteindicationsforfasciotomy.Theavoidance of compartment syndrome and restoration of limb function far outweigh the low morbidity associated with liberal use of fasciotomy. These patients are at significant risk of wound and other nosocomial infections and prolonged antibiotic use may be required.

The management of patients with complex injuries can be difficult; however, timely surgery and the involvement of a multidisciplinary team can produce rewarding results. One possible criticism of the above care could be failure to use the great toe, from the amputated left lower limb, to replace the patient’s right thumb.

References

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