Prostaglandin therapy of peripheral occlusive arterial disease

The mechanism of prostaglandin therapy in man is still poorly understood. We therefore investigated in 57 patients Fontaine stage II-IV the effect of a single intravenous infusion (37 POAD patients aged 36-67 years, mean 55.5) and the effect of a series of 14 therapeutic infusions (20 patients aged 32-77 years, mean 60.6). We employed a broad spectrum of methods including Doppler and photoplethysmographic pressure measurements and plethysmographic flow measurements in the toe, foot and calf, I-131 subcutaneous clearance in the lower leg, oral and skin temperature and blood gas analysis. Walking distances were estimated on a treadmill and compared with calf flows and ankle pressures. After a single infusion, blood flow in the foot and particularly in the toe rose while systemic and local pressures remained constant. Foot venous pCO2 dropped and pO2 rose dose-dependently. I-131 clearance did not change. After a series of infusions, ischaemic rest pain subsided and necroses were improved in all subjects with advanced ischaemia except one. In claudicating patients, a remarkable prolongation of walking distances without change in calf blood flow was found. It is concluded that prostaglandin therapy relaxes toe and foot skin vessels and is of considerable value in therapy of advanced skin ischaemia. It may also improve intermittent claudication. The mechanism of action includes, among other factors, a significant drop of local vascular resistance in the ischaemic areas and probably also an increase in capillary fraction of blood flow.