Transcutaneous oxygen and carbon dioxide during treatment of critical limb ischemia with iloprost, a prostacyclin derivative.

The effect of intravenous iloprost treatment (median rate: 1.6; range 1-2 ng/kg/min; 6 h daily over 4 weeks) on transcutaneous pO2 and pCO2 was studied in 8 patients with bilateral peripheral obstructive arterial disease and monolateral critical limb ischemia. Tensiometric determinations were obtained at both metatarsi in the supine and dependent position. In critically ischemic limbs, supine transcutaneous p)2 changed erratically during iloprost treatment, increasing in only three out of eight lower limbs. At variance with its inconsistent behavior in the supine position, dependent pO2 increased during drug administration (p<0.02). Transcutaneous pCO2 was unchanged by iloprost. In the contralateral, non-symptomatic limb, both supine and dependent pO2 values were increased by the drug, suggesting that systemic hemodynamic changes may participate in its effect on transcutaneous gas tension, even at infusion rates clinically titrated to avoid evident changes in blood pressure and heart rate.