An In Vitro Evaluation of Venous Cannula in a Simulated Partial (Femoro‐Femoral) Cardiopulmonary Bypass Circuit

: We designed a study to evaluate three factors (siphon gradient [PH], the right atrial pressure [RAP], and the inferior vena caval flow [IVCF]) to be optimized to maximize the venous drainage flow (DF) during partial cardiopulmonary bypass using eight venous cannulas of three different types and an original model circuit. The relationship between venous DF and the three factors is indicated by the multiple regression equation DF2= a PH +βRAP +γIVCF2+ C, where α, β, and γ are regression estimates and C is a constant. Multiple regression analysis results showed that DF was positively correlated with PH and RAP and negatively correlated with IVCF. A long cannula with 12 side holes and 60 cm long was considered to be useful to yield the optimal venous drainage flow under the condition of maintenance of the flow balance (DF and ICVF) and the pressure balance (RAP and IVCP) at the zero point. Moreover, this model may allow extensive research in flow dynamics of venous cannula without involving human subjects.