The DBT works on the principle of radial acceleration (with centrifugal forces). As blood passes through the fixed helix, the blood flow is turned into a rotating stream. Due to the centrifugal forces the more buoyant (lighter in physical weight) microbubbles are being concentrated in the center of the blood flow axis. Downstream at the distal end of the DBT is a small collection tube, where these bubbles are seperated with a small blood volume and taken through the recirculation line to the cardiotomy reservoir. Depending on the flow and the filling level of the Reservoir, the bubbles can dissolve in the reservoir.
The DBT is designed so that no hemolysis can be detected. The conical inlet slows down the bloodstream before it strikes the helix. The surfaces areas of the helix are minizied just as the collection tube distally, additionally the blood is being turned into rotiation softly and increasingly in the helix. After passing the helix, the bloodstream is being accelerated gently in the narrowing conus.
The DBT has 500 times less surface area compared to the arterial filter, which is an important factor for not creating any detectable hemolysis.