A newly developed miniaturized heart-lung machine--expression of inflammation in a small animal model

Cardiopulmonary bypass may cause severe inflammatory reactions and multiorgan failure, especially in premature and low-weight infants. This is due in part to the large area of contact with extrinsic surfaces and the essential addition of foreign blood. Thus, we developed a new miniaturized heart-lung machine (MiniHLM) with a total static priming volume of 102mL (including arterial and venous lines) and tested it in a small animal model. Seven Chinchilla Bastard rabbits were perfused with the MiniHLM (dynamic priming volume 127mL). Seven animals serving as a control were perfused using Dideco Kids and a Stöckert roller pump (modified dynamic priming volume 149mL). The rabbits were anesthetized and sternotomized, followed by cannulation of the aorta and the right atrium. The aorta was clamped for 1h. Blood for examination of inflammation (TNF-α, IL-1β, IL-6, IL-8, and IL-10) and blood gas analysis were taken before skin incision, 5min before opening of the aorta, 15min after opening of the aorta, and 4 h after the initiation of cardiopulmonary bypass. The parameters of inflammation were expressed by means of the comparative C(T) method (ΔΔC(T) method). After gradual reduction of perfusion with the HLM, the heart was decannulated, and the sternum was closed. All rabbits were successfully weaned from cardiopulmonary bypass. Blood gas analysis was unremarkable in all cases. Foreign blood was not administered. Although statistical significance was not achieved, there was a reduced expression of inflammatory markers in the MiniHLM group. The newly developed MiniHLM prototype was tested successfully in a small animal model in terms of technical function and expression of inflammation. Upcoming tests with the industrially manufactured MiniHLM may reveal the advantages of the MiniHLM in comparison with the conventional HLM.