IMPEDANCE RHEOGRAPHY COMPARED TO DOPPLER ULTRASOUND AS A SCREENING METHOD FOR PERIPHERAL ARTERIAL OCCLUSIVE DISEASE

Background: Determination of the ankle-arm-index (AAI) by Doppler ultr asound is the method of choice as a screening test for peripheral arte rial occlusive disease(PAOD). The easily performed Impedance Rheograph y (IR) may serve as an alternative screening method. This study invest igates the correlations between parameters obtained by IR curve to the AAI. Methods: 56 patients (62,8 +/- 13 years, m = 37, f = 19) were in cluded in the study IR,vas performed on both shanks rising ring electr odes below the knee and above the ankle (bipolar leads, frequency 90 k Hz, test voltage 2, 5 Vpp). The AAI was obtained by a 8 Mi ultrasound probe. Results: AAI less than or equal to 0,85 showed significant corr elations (p < 0.0001) to parameters of the IR curve: Crest Time (GZ, r = 0,67), Rise of the Pulse wave (PA, r = 0,82), Relative Pulse Volume (RT: r = 0,82) and the Rheographic Quotient (RQ, r = 0,86). AAI>0,85 showed no or only weak correlations to RI parameters. Underlying the f ollowing limits for rheographic parameters (GZ = 159ms, PA = 3,3, RP = 0,43vp/s and Re = 0,4 vp), sensitivity and specifity was determined: GZ: 68% and 100%, PA: 84% and 88%, RP: 68% and 92%, Re: 77% and 88%. C onclusion: Impedance rheography correlates significantly with the AAI. Therefore this method seems to be well suited as a screening test for PAOD.