PhD Thesis: Assessment of Disease Mechanisms and Compression Treatment in Venous Disease.
A. Abu-Own. UCL, London, 1995
I carried out some clinical research culminating in the award of a Ph.D. degree from University College London (UCL) in 1995. This research was based in the Vascular Laboratory of the Middlesex Hospital, where I became familiar with the administration and running of a non-invasive Vascular Laboratory, and acquired in-depth knowledge of all the investigative methods available for the assessment of both the macrocirculation and microcirculation in arterial and venous disease.
Here, I investigated the use of non-invasive techniques to assess disease mechanisms and examined the effects of compression in patients with venous disease. I studied 177 subjects (comprising patients with venous disease and normal control subjects).
In the first phase (Studies I -V), laser Doppler fluxmetry was used to examine the characteristics of skin blood flow and the effects of leg elevation and leg compression. The results showed that patients with chronic venous insufficiency had increased volume, but reduced speed, of blood in liposclerotic skin.
Both leg compression and leg elevation were shown to increase the microcirculatory blood cell velocity; this may have been part of the mechanism by which leg compression and leg elevation are beneficial in the treatment of patients with venous ulceration. In contrast to the supramalleolar region, it was found that the heel microcirculation was vulnerable to compression.
Lying on a conventional hospital bed reduced the laser Doppler flux signal to a minimal value while using a low air-loss support system maintained the interface pressure sufficiently low to prevent complete cessation of the heel microcirculation.
The second phase of this work (studies VI and VII) was concerned with compression in deep vein thrombosis prophylaxis. Colour duplex ultrasound imaging and strain gauge plethysmography were used to study the haemodynamic effects of intermittent pneumatic compression and graduated compression (TED) stockings.
The results indicated there was a haemodynamic advantage in the use of multi-chamber sequential intermittent compression compared to uniform single-chamber calf compression. The results also indicated a haemodynamic advantage in the combined use of TED stockings and intermittent pneumatic compression of the foot compared to using either of the two methods alone.