Heparin free long-term extracorporeal circulation using bioactive surfaces.

As already shown, a single bolus injection of heparin is sufficient to perform extracorporeal circulation (ECC) for long-term lung support if bioactive surfaces (HBS) are used. In the present study whether complete avoidance of systemic heparinization using HBS is possible was studied. Seven conscious sheep (50-60 kg) underwent venovenous bypass under standardized conditions using a Maxima capillary membrane oxygenator. Drug administration, surgery, and other conditions, such as priming volume and blood flow rates, were identical in all experiments. All blood contacting surfaces (oxygenator, catheters, etc.) were HBS. The ECC periods were set for 24 hr (n = 3) and 5 days (n = 4). At no time was heparin administered. No complications occurred in any experiment. Partial thromboplastin time, activated clotting time, and other coagulation parameters remained within physiologic ranges. Platelets did not drop below 80% of baseline values, and hemolysis rates were negligible. Blood gas data and other vital parameters were normal during the entire ECC period. Results show that HBS can be applied to long-term ECC, without the necessity for heparin administration.