TTL tips 14: Should I CTA this limb injury?

Not all limb-threatening injuries bleed dramatically. When we think about vascular injury, many of us picture pulsatile haemorrhage, expanding haematomas and dramatic physiology. Those patients are easy to spot. The challenge is the patient who looks relatively well. A small stab wound near the groin. A dislocated knee that’s now been reduced. A femoral fracture with apparently normal distal pulses. These are the injuries that can catch us out.

As TTL, you don’t need to know how to perform a vascular repair. You do need to recognise when an arterial injury might be present and make sure the patient reaches definitive care quickly.

The Obvious Ones

Some patients announce the diagnosis. An absent pulse, pulsatile bleeding, an expanding haematoma, a bruit, a thrill or signs of distal ischaemia should immediately raise concern for a significant arterial injury. These are the hard signs in patients who need vascular surgery involvement early. Most will require CT angiography, although the unstable patient may need to proceed directly to theatre.

The important thing is not to spend time convincing yourself that the injury is there. Assume it is.

The Less Obvious Ones

Many arterial injuries are far more subtle. Perhaps there was significant bleeding at scene that has now stopped. Perhaps there is a stable haematoma. Perhaps the injury sits uncomfortably close to a major vessel. These “soft signs” are where good trauma team leaders make a difference. They maintain suspicion when everyone else is becoming reassured. A patient can have a vascular injury without having a dramatic vascular signs.

A small stab wound near a major vessel can create:

Intimal injury
Pseudoaneurysm
Arteriovenous fistula

Know the Injury Patterns

Some mechanisms should automatically make you think about blood vessels. Knee dislocations are the classic example. Even when reduced successfully, there remains a significant risk of popliteal artery injury. Similarly, penetrating injuries adjacent to major neurovascular structures deserve respect. The external wound may be small, but the underlying injury may not be.

Examples include:

Knee dislocation
Posterior knee trauma
Supracondylar humeral fractures
Elbow dislocations
High-energy femoral fractures
Penetrating injuries adjacent to major neurovascular bundles

Think Beyond the Primary Survey

One of the reasons arterial injuries are missed is that they don’t always declare themselves immediately. A penetrating injury may later develop into a pseudoaneurysm or an arteriovenous fistula. The patient who appears stable in resus may return days or weeks later with complications that were present from the start. If the mechanism and anatomy make you uncomfortable, have a low threshold for CT angiography.

Remember the Clock

Every minute of limb ischaemia matters. As a rule of thumb, restoration of perfusion should occur within six hours if we want to maximise the chances of limb salvage. When you identify a threatened limb, make things happen (quickly).