A new top-loading venous bag provides vacuum-assisted venous drainage

A new venous bag has been developed, prototyped, and tested. The new bag has its inlet, outlet purge, and infusion tubes extending upward from the top of the bag, and are threaded through, bonded to, and sealed within a flat rigid top plate. This design allows the bag to be hung from its top plate by its tubes. It also allows the bag to be: 1) dropped into or removed from its holder, as is done with existing hard-shell reservoirs so that its weight pulls it into the holder without the need for eyelets and hooks and 2) placed closer to the floor so that gravity drainage is facilitated. The V-Bag (VB) is easily sealed within an accompanying rigid housing. Once sealed, vacuum applied to the housing is transmitted across the flexible walls of the bag to the venous blood. Thus, vacuum-assisted venous drainage (VAVD) is obtained as it is with a hard-shell reservoir, but without any contact of air with the blood. Bench tests, using a circuit that simulated the venous side of the cardiopulmonary bypass (CPB) circuit, showed that applying suction to the housing increased venous flow, and the fractional increase in flow was not a function of the venous cannula, but of the level of vacuum applied. In the gravity drainage mode, the bubble counts at the outlet of the V-Bag compared to two other bags were lower at any pumping condition. When used in the VAVD mode, bubble counts were two orders of magnitude lower than when using kinetically assisted venous drainage (KAVD) with a centrifugal pump. Results obtained with the VB suggest its clinical usefulness.