Recommendations for Physiological Testing
COR	LOE	Recommendations
I	B-NR	Toe-brachial index (TBI) should be measured to diagnose patients with suspected PAD when the ABI is greater than 1.40.72,99–102
See Online Data Supplement 5.		TBI is a noninvasive test that is useful to evaluate for PAD in patents with noncompressible arteries, which cause an artificial elevation of the ABI.99,100,102,103 A TBI ≤0.70 is abnormal and diagnostic of PAD because the digital arteries are rarely noncompressible.99–102,104,105 Patients with longstanding diabetes mellitus72,101 or advanced chronic kidney disease106 have a high incidence of noncompressible arteries. Therefore, TBI assessment allows for the diagnosis of PAD in these patients with noncompressible arteries who have history or physical examination findings suggestive of PAD (Figure 1).
I	B-NR	Patients with exertional non–joint-related leg symptoms and normal or borderline resting ABI (>0.90 and ≤1.40) should undergo exercise treadmill ABI testing to evaluate for PAD.71,74,107–110
See Online Data Supplement 5.		Exercise treadmill ABI testing is important to objectively measure symptom limitations and diagnose PAD.71,74,107–110 It is useful in establishing the diagnosis of lower extremity PAD in the symptomatic patient when resting ABIs are normal or borderline and to differentiate claudication from pseudoclaudication in individuals with exertional leg symptoms. If the post-exercise treadmill ABI is normal, alternative causes of leg pain are considered (Table 6). If a treadmill is not available, the pedal plantarflexion ABI test is a reasonable alternative because the results correlate well with treadmill ABIs (Figure 1).111
IIa	B-NR	In patients with PAD and an abnormal resting ABI (≤0.90), exercise treadmill ABI testing can be useful to objectively assess functional status.71,74,107–110
See Online Data Supplement 5.		In patients with PAD, exercise treadmill ABI testing can objectively assess symptoms, measure change in ABI in response to exercise, and assess functional status71,74,107–110 (Figure 1). It can be useful to correlate exertional lower extremity symptoms to a decline in ABI after treadmill exercise. Exercise treadmill ABI testing can document the magnitude of symptom limitation in patients with PAD and provide objective data that can demonstrate the safety of exercise and help to individualize exercise prescriptions in patients with PAD before initiation of a formal program of structured exercise training. Exercise ABI may also be used to objectively measure the functional improvement obtained in response to claudication treatment (eg, structured exercise program or revascularization). Administration of a 6-minute walk test in a corridor is a reasonable alternative to treadmill ABI testing for assessment of functional status.54
IIa	B-NR	In patients with normal (1.00–1.40) or borderline (0.91–0.99) ABI in the setting of nonhealing wounds or gangrene, it is reasonable to diagnose CLI by using TBI with waveforms, transcutaneous oxygen pressure (TcPO2), or skin perfusion pressure (SPP).112–116
See Online Data Supplement 5.		The toe pressure and TBI may be discordant with the ABI 0.90 to 1.40 in some patients with diabetes mellitus and a nonhealing wound (Figure 2).115,116 A TBI ≤0.70 is considered diagnostic of PAD.101,104,105 Doppler or plethysmographic waveforms taken at the toe supplement the toe pressure and TBI measurement and may be severely dampened in the setting of CLI. The likelihood of wound healing decreases with toe pressure <30 mm Hg.100 Perfusion assessment measures (ie, TBI with waveforms, TcPO2, SPP) are obtained in a warm room to prevent arterial vasoconstriction in response to the cold. TcPO2 measurements are performed with a standardized protocol and are taken at multiple sites.117 Correlation between TBI, TcPO2, and SPP has been reported.113 TcPO2 >30 mm Hg has been used to predict ulcer healing.118 SPP ≥30 to 50 mm Hg is associated with increased likelihood of wound healing.113 If perfusion measures are normal or only mildly impaired, alternative causes of the nonhealing wounds are considered (Table 7). TcPO2 and SPP can be used in angiosome-targeted assessment for revascularization.119
IIa	B-NR	In patients with PAD with an abnormal ABI (≤0.90) or with noncompressible arteries (ABI >1.40 and TBI ≤0.70) in the setting of nonhealing wounds or gangrene, TBI with waveforms, TcPO2, or SPP can be useful to evaluate local perfusion.112–116
See Online Data Supplement 5.		Perfusion assessment measures (eg, TBI with waveforms, TcPO2, SPP) can be useful when the ABI is only mildly reduced (eg, ABI 0.70–0.90) to determine whether factors other than PAD may be contributing to impaired wound healing (Figure 2). These perfusion assessment measures are obtained in a warm room to prevent arterial vasoconstriction in response to the cold. TcPO2 measurements are performed with a standardized protocol and are taken at multiple sites.117 The likelihood of wound healing decreases with toe pressure <30 mm Hg.100 There is correlation between TBI, TcPO2, and SPP. TcPO2 >30 mm Hg has been used to predict ulcer healing.118 SPP ≥30 to 50 mm Hg is associated with increased likelihood of wound healing.113 TcPO2 and SPP can be used in angiosome-targeted assessment for revascularization.119 Additional perfusion assessment may also be useful for patients with nonhealing wounds or gangrene who have noncompressible arteries (ABI >1.40) but who have a diagnosis of PAD that is based on an abnormal TBI (ABI ≤0.70).