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Title: Optical and other methods for the assessment of arterial and venous insufficiency
Author: Williams, Paul
ISNI:       0000 0004 2732 3977
Awarding Body: Cardiff University
Current Institution: Cardiff University
Date of Award: 2011
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There are a number of different techniques used to diagnose vascular insufficiency ranging from expensive hospital based equipment to less expensive devices used in primary care centres. Currently, some of these devices are unsuitable for use on patients with diabetes or DVI and have poor sensitivity for detecting moderate PAD patients. Additionally, some of the tests, particularly for DVI, require tourniquets or the patient to perform postural changes which some may find difficult. This may extend testing time. The study investigated 2 groups of patients, one with PAD and the other with DVI. The arterial group consisted of 46 controls and 57 patients. PPG probes were placed on the index finger and great toe. The venous group consisted of 24 controls and 25 patients and PPG probes were placed behind the knee and 10 cm above the medial malleolus. Duplex ultrasound was used as the gold standard to assess the arteries and veins in the lower limbs. The aim was to investigate whether signals acquired from patients at rest using Photoplethysmography (PPG) could be used as a screening tool. Pulse wave transit time (PWTT) and shape analysis techniques were used on the pulses from the patients with PAD, while time base and spectral analysis techniques were used on the waveforms of patients with DVI. PWTT and shape analysis techniques achieved sensitivities and specificities of 82% and 84% respectively. Accuracy dropped to 70% for detecting patients with moderate PAD. Spectral analysis techniques gave the best results for detecting patients with DVI achieving sensitivities and specificities of 69% and 80% respectively. In conclusion, reducing the signal acquisition time on patients with PAD did not significantly reduce the sensitivity and specificity. Without any patient movement it was difficult to separate patients with DVI from healthy normals.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: R Medicine (General) ; TA Engineering (General). Civil engineering (General)