Optimized veno-venous bypass with the affinity pump

Veno-venous bypass (VVBP) is increasingly used to avoid acute venous hypert ension and low cardiac output after clamping the vena cava. Air embolism up on accidental decannulation of the inflow line and endothelial damage due t o suction of the blood collecting cannula to the vessel wall are known comp lications specific to the currently used roller and centrifugal pumps, beca use they generate negative pressure at the inflow site of the pump. The Aff inity pump has a unique chamber design with an occlusive segment, that coll apses in low filling states preventing negative pressure at the inflow site of the pump chamber. This device was tested for VVBP in three pigs (each w eighing 52.3 +/- 5.1 kg) with hepatic vascular exclusion. Blood was pumped from the femoral and portal veins to the external jugular vein and perfusio n was maintained for 6 hours. The hemodynamic state of the animals was asse ssed by recording heart rate; systolic, mean arterial, and diastolic pressu re; as well as central venous pressure. Mean pump flow during the experimen t was 1,629.3 +/- 372.2 ml/min. After clamping, the inflow line of the pump mean arterial pressure significantly decreased (from 69.5 +/- 4.4 to 43.1 +/- 3.5 mm Hg), and mean pressure in the femoral vein increased significant ly (from 16.1 +/- 2.6 to 26.8 +/- 5.9 mm Hg), whereas the mean pressure in the internal jugular vein did not significantly change (from 6.0 +/- 1.7 to 5.0 +/- 2.1 mm Hg). There was no suction by the blood collecting cannula o n the vessel wall, and neither bubbles nor air emboli were detected and no operator intervention was needed. In conclusion, the Affinity pump eliminat es device related complications due to negative pressure generated at the i nlet, and guarantees stable hemodynamics. Its application is simple and saf e and minimal operator intervention is needed, making the Affinity pump par ticularly suited for veno-venous bypass.