The StethoDop: a Doppler stethoscope attachment for investigation of arterial and venous insufficiency of the lower extremities.

BACKGROUND The aim of the current study was to investigate whether the StethoDop can serve as a valid and reproducible instrument for measuring the ankle-brachial index (ABI) and assessing venous reflux, even when used by inexperienced investigators, in comparison with the classic Doppler. METHODS I) During four weeks, four ankle-brachial index (ABI) measurements were performed on 44 patients: one measurement with the classic Doppler by an experienced investigator, one with the classic Doppler by an inexperienced investigator and two measurements with the StethoDop by the inexperienced investigator. II) 36 patients were screened for venous insufficiency by detecting venous reflux with the StethoDop and classic Doppler at the saphenofemoral and saphenopoplitial junctions by an inexperienced investigator. The results were compared with the results of the duplex as gold standard and with the results of the examination by an experienced dermatologist with the classic Doppler. RESULTS I) The confidence interval of ABI measurement for both the classic Doppler and the StethoDop by the inexperienced investigator was within an acceptable +/- 0.21 interval of significant change. II) For venous reflux determination, the overall sensitivity and specificity of the StethoDop were comparable with the sensitivity and specificity of the classic Doppler: sensitivity 76.0 and 75.0%, specificity 94.8 and 94.2%, respectively. The positive predictive value of the StethoDop, compared with the duplex, was 87.5%; the negative predictive value was 90.0%. CONCLUSION I) For ABI measurement, the StethoDop is a valid instrument with reproducible results, even when used by inexperienced investigators. II) For venous reflux determination, the StethoDop is a valid screening instrument for venous insufficiency. However, as with determination with the classic Doppler, the reflux assessment by StethoDop gives no information about the deep veins and may miss up to 24% of apparent reflux.