Abstract: Improvements to integrated blood pump/oxygenator having a rotating hollow fiber bundle assembly that both oxygenates and pumps blood are provided. A plurality of vanes arranged along a central shaft of the device increase pressure near the center of the fiber bundle to prevent microbubble generation and blood trauma. Shearing loads imposed on the fiber elements of the fiber bundle are reduced by the addition of a reinforcement structure, while the gas flow path is configured to minimize flooding and loss of oxygenation efficiency due to occasional rupture of fiber elements. Blood trauma may be further reduced by contouring the vanes and other components of the device.