Doppler-determined arterial systolic blood pressure in injured limb divided by systolic blood pressure in uninjured limb
<0.9 abnormal, > 0.9 is highly sensitive for excluding major<unk> 
NPV of IEI >0.9 is ~96%
Allows for serial, objective monitoring
Only detects obstructive lesions
Unreliable in proximal injuries, popliteal injuries, shotgun wounds, multiple wounds, shock
False negative with deep femoral artery injury
<0.9 abnormal, > 0.9 is highly sensitive for excluding major<unk> 
NPV of IEI >0.9 is ~96%
Allows for serial, objective monitoring
Only detects obstructive lesions
Unreliable in proximal injuries, popliteal injuries, shotgun wounds, multiple wounds, shock
False negative with deep femoral artery injury
NPV of IEI >0.9 is ~96%
CT Angiography
The Gold standard for excluding<unk> 
Highest sensitivity, specificity
Useful for detection of other injuries(Venous, neural, fractures, etc)
Dupplex Doppler
Can be operator dependent and does NOT definitively exclude arterial Injury
S 95-100%; Sp 97-100%; Acc 98-100%
Sens for vessel injury, thrombosis, pseudoaneurysm, intimal flap and A-V fistula
Point of care ultrasound
useful as an adjunct, but there are no randomized trials proving sensitivity.
The Gold standard for excluding<unk> 
Highest sensitivity, specificity
Useful for detection of other injuries(Venous, neural, fractures, etc)
Can be operator dependent and does NOT definitively exclude arterial Injury
S 95-100%; Sp 97-100%; Acc 98-100%
Sens for vessel injury, thrombosis, pseudoaneurysm, intimal flap and A-V fistula
useful as an adjunct, but there are no randomized trials proving sensitivity.
Immediate arterial exploration without further investigation
Perform API → if <0.9 obs/admit for 24h, serial API
Consider:
Doppler U/S
CT angiogram
Evaluation of compartment pressures
Doppler U/S
CT angiogram
Evaluation of compartment pressures
Vascular injury
Compartment syndrome
Tendon injury
Contusion
Cold injuries
Crush syndrome
Trauma 
Degloving injury