Prolonged infusion of prostacyclin in patients with advanced stages of peripheral vascular disease: a placebo-controlled cross-over study

Twelve patients (age 33-77 years, mean age 68.4 years) with peripheral vascular disease (PVD) stage III-IV received continuous intravenous infusions of 5 ng prostacyclin (PGI2)/kg/min and physiological saline for 7 days. The administration was randomized and double-blind with an interval of 7 days between the infusions. During PGI2 infusion systolic blood pressure fell significantly from 147.8 +/- 4.8 mm Hg to 140.6 +/- 4.0 mm Hg (P less than 0.01) and returned to 144.5 +/- 4.9 mm Hg post infusion. Transcutaneous pO2 (tcpO2) measured on the instep of the affected limb increased significantly by 8.9 +/- 3.8 Torr during PGI2 infusion and remained elevated during the subsequent week. A significant reduction of pain was observed from the 5th day of PGI2 infusion, lasting for at least the following observation period. Platelet cAMP increased from 18.8 +/- 1.5 pmol/10(8) platelets to 24.7 +/- 1.6 pmol/10(8) platelets on the 3rd day of PGI2 infusion (P less than 0.01). Spontaneous platelet aggregation was also significantly reduced during PGI2 infusion. However, 7 days after the infusion thromboxane B2 (TXB2) in plasma and spontaneous platelet aggregation significantly increased in comparison with the preinfusion values, indicating a rebound phenomenon. The clinical outcome was favorable in 9 of 12 patients, was unchanged in two patients, while progressing to limb amputation in one patient.