An extracorporeal reservoir device including a housing, a venous inlet sub-assembly, and a venous filter. The venous sub-assembly is mounted to the housing and includes a downtube and a luer port connector body. The connector body extends from the downtube and forms a passageway open to a lumen of the downtube. The connector body is arranged such that fluid flow from the passageway merges with a flow path of fluid along the primary lumen at an angle of less than 90°. Secondary blood flow through the port connector body is less likely to induce turbulent flow into venous blood flow within the downtube, and is thus less likely to break up any bubbles carried by the venous blood. For example, at port flow rates of less than 500 mL/minute, fluid flow from the port connector body does not induce turbulent flow into fluid flowing through the primary lumen.
