Enhanced oxygen delivery induced by perfluorocarbon emulsions in capillary tube oxygenators

Previous studies showed that a new generation of perfluorocarbon (PFC) emulsions increased tissue PO₂ in the cat retina to a degree that could not be explained by the small increase in arterial O₂ content seen after the infusion of low doses of 1 g PFC/kg body weight. It seems that increased O₂ delivery at the tissue level after PFC infusion is caused by a local effect in the microcirculation. The authors studied this effect in vitro at steady state in a closed loop circuit, consisting of one of two types of capillary tube oxygenators, deoxygenator(s), a reservoir bag filled with anticoagulated bovine blood or saline (control), and a roller pump, to see if the addition of PFC would have an effect on the PO₂ difference (Δ PO₂) across the capillary tube membrane oxygenator at a blood flow rate of 3 l/min. Perfluorocarbon was added in three incremental doses, each giving about 0.7 vol% of PFC. The Δ PO₂ across the oxygenator was measured before and after each dose. The mean percent increases in Δ PO₂ in blood for two types of oxygenators were 19.2 ± 8% (mean ± SD, n = 6, P = 0.002) and 9.9 ± 4% (n = 3, P = 0.05), respectively, whereas the mean percent change in Δ PO₂ in saline was -4.9 ± 2% (n = 2, P = 0.2). Inlet PO₂s to the oxygenator were only minimally increased. The authors conclude that O₂ delivery was significantly enhanced after injection of PFC in blood in this capillary tube model. A near wall excess of PFC particles may account for the augmentation of O₂ diffusion in this model.