Mills et al reported the Society for Vascular Surgery Lower Extremity Threatened Limb Classification System. This consists of 3 components, one of which is a grade for ischemia. The authors are from the University of Arizona, the University of California San Francisco, St. Elizabeth's Medical Center (Brighton, Mass), the University of Massachusetts, George Washington University and Valley Presbyterian Medical Center (Van Nuys).
Patient selection: peripheral arterial disease involving a lower extremity
Parameters:
(1) ankle-brachial index (ABI)
(2) ankle systolic blood pressure in mm Hg
(3) toe pressure (TP) in mm Hg
(4) transcutaneous oximetry (TcPO2)in mm Hg
ABI
Ankle SBP
Toe Pressure
Tc oximetry
Grade
0.80 to 1.3
> 100
>= 60
>= 60
0
0.60 to 0.79
71 to 100
40 to 59
40 to 59
1
0.40 to 0.59
50 to 70
30 to 39
30 to 39
2
<= 0.39
< 50
< 30
< 30
3
If the ABI is > 1.3 (incompressible) then grade based on TP or TcPO2.
If the patient has diabetes then measure toe pressure since the ABI may be falsely elevated.
A minimally or nonpulsatile forefoot (on pulse volume recording) is Grade 3.
If results are discrepant then grade based on toe pressure.
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