Pressure indices in peripheral arterial disease assessed by infrared photosensors

Ankle-brachial index (ABI) assessment by Doppler is operator dependent and limited in calcified arteries. For the detection of peripheral arterial disease (PAD), we evaluated ABI and toe-finger (ToFi) pressures by infrared (IR) sensors at the digits and compared with standard Doppler (Doppler-ABI) in 100 patients with PAD and in 15 controls. Pressure indices were obtained in 86% for Doppler-ABI, 82% for IR-ABI, and 94% for IR-ToFi (P < .01). According to Bland-Altmann analysis, IR-ABI and Doppler-ABI are exchangeable (limits of agreement [loa] -0.30; 0.30, bias -0.003, 95% confidence interval [CI] -0.02; 0.02), whereas IR-ToFi was not (loa -0.23; 0.61, bias of 0.2, 95% CI 0.16; 0.23). The IR-ToFi revealed the best inter- and intrarater agreement (0.92/0.98) followed by IR-ABI (0.74/0.98) and Doppler-ABI (0.66/0.89). Ankle-brachial arterial pressure index can be assessed by IR photosensors. Although toe-finger index is not exchangeable with standard Doppler, it will need further exploration to define its value for the diagnosis of PAD due to its excellent inter- and intrarater agreement.