Acute and chronic paediatric limb ischaemia

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dalsing
Michael Dalsing

Nothing is more frightening than an injured child. In general, paediatric limb ischaemia is a traumatic event presenting with varying degrees of severity. Paediatric vascular trauma is fortunately observed in only about 1% of all paediatric trauma series. The traumatic etiology is age=related with the majority of infants and children <2 years old suffering an iatrogenic event (catheterisation diagnostic or monitoring), those from 2 to 12 years old suffering from blunt trauma such as a fall or playground injury, and older children (reminiscent of adults) experiencing some type of penetrating trauma (eg. gunshot or car accident). Infants and young children more commonly present with leg ischaemia (eg. groin arteries); middle aged children more often experience arm ischaemia, while older children have a slight preponderance for lower leg injury.

The clinical presentation is similar to adults with the exception of the inability of younger patients to express pain and sensory loss. A history of the injury, type and extent—sometimes obtained from a responsible adult—is important as an indicator of trauma severity. After a standard trauma examination, a careful limb examination is warranted to listen for bruits or thrills, to palpate all pulses with Doppler assistance to determine the ankle/brachial index (ABI) or wrist/brachial index (WBI) as a haemodynamic confirmation and estimate of ischaemia. Children older than one year of age have an ABI of >0.9, as would be expected in an adult, while those less than one year may have an ABI averaging 0.88+/-0.11. Although arterial spasm is a prominent reaction to trauma in children, a return to normal within a few hours is expected or thrombosis should be assumed until proven otherwise. Vigilance is very important because the infant/young child cannot express pain or describe sensory loss. Although not typically described in the paediatric literature, I would like to make a plea that the Rutherford classification of acute limb ischaemia be applied to this patient population to provide a standard method of determining the need for aggressive intervention. A missed diagnosis can have limb loss implications and the combination of clinical findings and mechanism of injury (eg. knee dislocation) should drive the need for diagnostic confirmation or immediate operation. An expeditious operative intervention is required to control active bleeding, for symptomatic injury (eg. arteriovenous fistula with heart failure) and imminent limb loss (Rutherford class 2b ischaemia after best medical care).

Confirmatory studies consist of duplex imaging which can be quite accurate in the hands of well-trained personnel and is preferred over more invasive studies if applicable. In traumatised patients, including the paediatric population, computerised tomographic angiography has replaced convention angiogram with excellent accuracy in both blunt and penetrating injuries. Angiography is generally indicated only if a therapeutic percutaneous option for treatment is being considered and is likely.

Management is generally based on patient age and presentation. Neonates and infants (<2 years old) have very small arteries, prone to intense vasospasm and appear to develop collateral flow quite rapidly. These patients often present with less limb-threatening events with acceptable capillary refill, the absence of skin mottling, and often audible distal Doppler signals (Rutherford class 1, 2a). But even in more severe initial presentations, therapeutic heparin anticoagulation and symptomatic care results in a viable limb in 90–95% of cases, even with a return of normal pulses. Systemic thrombolysis can be considered in non-responders if bleeding is not a significant risk. Surgery is warranted only in life- or limb-threatening situations. Even those children less than 6 years old are often managed best by anticoagulation and symptomatic care with less than a quarter experiencing long-term limb length discrepancies. Older children tolerate operative intervention better and are treated more like adults, especially as they mature. However, in the final analysis, the decision to operate rests on the degree of ischaemia, the medical condition of the child, and the risk of a vascular intervention. If open operation is required some helpful tips are: the use of systemic anticoagulation, the use of saphenous vein in those >10kg in size, a topical/intravascular vasodilator to reduce vasospasm, loupe or microscope magnification, spatulation of the graft ends to double the diameter, and use fine prolene sutures in interrupted fashion for the anastomosis. Fasciotomy should be considered as per adult indications.

When managed as described above, the limb salvage rate for infants and children younger than 2 years is quite good, with a return to normal perfusion at a rate of 70–90%. The majority of those older than 2 years also have an an excellent limb salvage rate if vascular injury was an isolated event and there was no delay in the diagnosis. Associated injuries can be detrimental and the use of the mangled extremity severity score has a prognostic accuracy of over 90%. From the data available, the saphenous vein provides a stable conduit over time when used in a child’s extremity. Mortality is near zero in the case of isolated vascular injury but with associated injuries, in particular traumatic head injury, the results can be more devastating.

In conclusion, paediatric extremity vascular injuries are uncommon and the diagnosis can be challenging, especially in the very young. A high index of suspicion is warranted, especially when vascular monitoring or interventions have been required or the child has been injured. The ischaemic limb presents with the 5 Ps (pale, pulseless, painful, paralysed and paraesthetic), as in adults (Rutherford classification) but can be difficult for a young child to communicate. Diagnostic confirmation helps to determine the haemodynamic consequences (arterial Doppler study) and the location of injury (duplex, or more commonly CTA). Fortunately, for children older than 6 years and especially those younger than 2 years, systemic anticoagulation generally results in a salvaged limb. Children older than 6 years are treated more aggressively with vascular interventions. Limb salvage per se is common in the absence of associated injury or a delay in diagnosis. Mortality is a consequence of associated injuries.

References:

  1. Dalsing MC, Cikrit DF, Sawchuk AS. J Vasc Surg 2005;41:983–7.
  2. Dalsing MC, Sohn ME, Cikrit DF, et al. Trends in Vascular Surgery 2007;chapter 21:215–229.
  3. Matos JM, Fajardo A, Dalsing MC, et al. J Vasc Surg 2012;55:1156–9.

Michael C Dalsing is at Indiana University Health, Indianapolis, USA