Nurse-led rapid access vascular examination clinic triage reduces inappropriate referrals for peripheral arterial disease.

INTRODUCTION: Peripheral arterial disease causing intermittent claudication (IC) causes decreased quality of life and significant morbidity. We hypothesized that triage of patients referred with suspected IC at a nurse-led rapid access vascular examination (RAVE) clinic would identify those patients requiring vascular surgery assessment. METHODS: A prospective cohort study was performed. Patients referred with suspected IC were assessed using the Edinburgh claudication questionnaire (ECQ) and arterial Doppler assessment with segmental waveform analysis and calculation of ankle brachial pressure index (ABPI). Data were collected regarding cardiovascular risk and its modification. RESULTS: Of 451 consecutive patients, mean age was 65 years (range 30-89). Cardiovascular risk factors included: 173/451 (38%) current smokers (162/451 (36%) were ex-smokers); diabetes, 22%; hypertension, 46%; ischaemic heart disease (angina), 29%; dyslipidaemia, 27%. Therapeutic risk modifications included: antiplatelet therapy, 64.4%; lipid-lowering therapy, 57.8%. abnormal ABPI readings were present in 264/451 (59%), with ratio <0.9 in 209/451 (46.3%), >1.3 in 48/451 (10.6%), and incompressible vessels 7/451 (1.5%). Normal ABPI (ratio >0.9 and <1.3, triphasic Doppler waveforms) were found in 187/451 (41%), these patient were considered inappropriate referrals. Considering those patient with PAD diagnosed on abnormal ABPI (<0.9 or >1.3), Doppler waveform analysis was more sensitive and specific than ECQ. CONCLUSIONS: Diagnosis of IC with clinical history alone is inaccurate in 41 percent of cases, leading to inappropriate referral to vascular surgery. Doppler waveform analysis had excellent sensitivity and specificity for prediction of ABPI <0.9. ABPI measurement in primary care could result in a more efficient use of clinical resources.

Comparison of CW Doppler ultrasound spectra with the spectra derived from a flow visualization model.

The methods and results of a study to determine the accuracy of continuous wave (CW) Doppler spectral recordings by comparison to the spectra derived from the flow profiles photographed simultaneously in a pulsatile flow visualization model are reported in this paper. A pulsatile pump produced a flow velocity waveform, similar to that seen in the human femoral artery, in a quartz glass tube. The velocity profiles, which were made visible by using a photochromic dye/laser technique, were photographed, and at the same time the instantaneous Doppler spectra were recorded. A comparison of the Doppler data and the photographed profiles gave the following results. The Doppler spectrograms and those reconstructed from the flow visualization data were quite similar. Excellent agreement was observed between the instantaneous maximum and mean Doppler waveforms. Individual spectra showed some differences and these differences were quantified by the novel application of certain statistical shape descriptor coefficients that are based on the estimation of the higher order moments of the spectra. The Doppler spectra are generally more skewed towards higher frequencies, narrower, and more peaked than the flow visualization spectra. Analysis of the assumptions and various sources of error lead to the conclusion that the differences were probably caused by ultrasound beam nonuniformity and the effects of refraction, causing a reduction of the beam field response at the tube edges. It is concluded that provided certain precautions are taken in the measurement technique, the CW Doppler ultrasound spectra fairly accurately represent the true velocity profile.