Impedance plethysmography as an alternative method for the diagnosis of peripheral arterial disease

Background and objective: In the diagnosis of peripheral artery disease (PAD), the ankle-brachial index (ABI) is considered as the standard, and other noninvasive methods have received too little attention. Therefore, the aim of the study was to determine the diagnostic accuracy of impedance plethysmography in diagnosing PAD and to compare this method with other methods.
Materials and methods: A total of 66 patients with a mean age of 76.1 ± 9.6 years who had been treated for various cardiovascular diseases at Kaunas Clinical Hospital during 2011–2012 were enrolled into the study. All the patients were screened for PAD. Impedance plethysmography was performed with a new-generation Niccomo^TM device. The receiver operating characteristic analysis was employed to determine the diagnostic accuracy of 4 parameters of impedance plethysmography: crest time (CT), crest width (CW), pulse amplitude (P_ampl), and alternating blood flow (ABF).
Results: There were a significant correlation between the ABI and the CT (r = 0.699, P < 0.001), between the ABI and the ABF (r = 0.552; P < 0.001), and between the ABI and the P_ampl only among men (r = 0.652; P < 0001). No correlation was found between the ABI and the CW. Among all the parameters, the CT had the highest sensitivity and specificity (73.2% and 96.0%, respectively). Other parameters had the following sensitivities and specificities: ABF, 61.0% and 96.0%; and P_ampl, 90.0% and 20.0%, respectively.
Conclusions: Impedance plethysmography, especially its parameter CT, is an alternative non- invasive method in diagnosing PAD and could be used for the screening of patients with PAD.