A PROSPECTIVE COMPARISON OF ATRIO-FEMORAL AND FEMORO-ATRIAL FLOW IN ADULT VENOVENOUS EXTRACORPOREAL LIFE-SUPPORT

Introduction: In the United States, venovenous extracorporeal life sup port has traditionally been performed with atrial drainage and femoral reinfusion. (atrio-femoral flow). Although flow reversal (femoro-atri al flow) mav alter recirculation and extracorporeal flow no direct com parison of these 2 modes has been undertaken. Objective: Our goal was to prospectively compare atrio-femoral and femoro-atrial flow in adult venovenous extracorporeal life support for respiratory failure. Metho ds: A modified bridge enabling conversion between atrio-femoral and fe moro-atrial flow was incorporated in the extracorporeal circuit. Bypas s was initiated in the direction that provided the highest pulmonary a rterial mixed venous oxygen saturation, and the following measurements were taken: (1) maximum extracorporeal flow (2) highest achievable pu lmonary arterial mixed venous oxygen saturation, and (3) flow required to maintain the same pulmonary arterial mixed venous oxygen saturatio n in both directions. Flow direction was then reversed, and the measur ements mere repeated. Data were compared with paired t tests and are p resented as mean +/- standard deviation. Results: Ten patients were st udied, and 9 were included in the data analysis. Femoro-atrial bypass provided (1) higher maximal extracorporeal flow (femoro-atrial flow = 55.6 +/- 9.8 mL/kg per minute, atrio-femoral flow = 51.1 +/- 11.1 mL/k g per minute; P =.04) and (2) higher pulmonary arterial mixed venous o xygen saturation (femoro-atrial flow = 89.9% +/- 6.6%, atrio-femoral f low = 83.2% +/- 4.2%; P =.006); (3) further-more, it required less flo w to maintain an equivalent pulmonary arterial mixed venous oxygen sat uration (femoro-atrial flow = 37.0 +/- 12.2 mL/kg per minute, atrio-fe moral flow = 46.4 +/- 8.8 mL/kg per minute; P =.04). Conclusions: Duri ng venovenous extracorporeal life support, femoro-atrial bypass provid ed higher maximal extracorporeal flow higher pulmonary arterial mixed venous oxygen saturation, and required comparatively less flow to main tain an equivalent mixed venous oxygen saturation than did atrio-femor al bypass.