INTRAVENACAVAL MEMBRANE-OXYGENATION AND CARBON-DIOXIDE REMOVAL IN SEVERE ACUTE RESPIRATORY-FAILURE

Study objective: To characterize the physiologic response to, and safe ty of, intravenacaval membrane oxygenation and carbon dioxide removal. Design: Interventional before-after study. Setting: University teachi ng hospital ICU. Patients: Twenty-two patients with severe acute respi ratory distress syndrome (ARDS). Interventions: Implantation of a holl ow-fiber membrane oxygenator (IVOX; CardioPulmonics; Salt Lake City, U tah) into the superior and inferior venae cavae by venotomy of the rig ht femoral or right internal jugular vein for a duration of up to 20 d ays. Measurements: Hemodynamic measurements using pulmonary artery and systemic artery catheters, ventilator settings (FIO2, minute ventilat ion, peak inspiratory pressure, and positive end-expiratory pressure), arterial and mixed venous blood gases (pH, PCO2, PO2, and measured sa turation), and clinical laboratory determinations (CBC, fibrinogen, pl asma hemoglobin, complement C3 and C5) were obtained. Calculations of PaO2/FIO2 ratio and PaCO2-V-E product were used to assess gas exchange efficacy. Microbiologic cultures were obtained from the device and wo und following explantation. Survival to ICU discharge and hospital dis charge were recorded. Results: Implantation was successful in 20 of 22 patients. Gas exchange rates averaged 50.4 +/- 15.8 mL . min(-1) for carbon dioxide and 71.1 +/- 20.2 mL . min(-1) for oxygen. A reduction in FIO2 from 0.78 +/- 0.16 to 0.63 +/- 0.21 and in V-E from 177 +/- 94 mL . kg(-1) . min(-1) to 127 +/- 58 mL . kg(-1) . min(-1) was possibl e within 4 h postimplantation. By 12 h, FIO2 was reduced to 0.57 +/- 0 .18. Indices of gas exchange improved significantly after implantation , with PaO2/FIO2 ratio increasing from 79 +/- 20 to 112 +/- 47 and PaC O2-V-E product decreasing from 7.6 +/- 4.2 to 4.9 +/- 2.5 within 4 h. A significant reduction in peak inspiratory pressure was achieved (45 +/- 10 to 38 +/- 9 cm H2O). Major complications were blood loss during implantation requiring transfusion in 11 patients, a retroperitoneal bleed in 1 patient, and femoral deep venous thrombosis in 4 patients, but there were no long-term sequelae or IVOX-related deaths. The ICU a nd hospital survival were 10/20 (50%) and 8/20 (40%), respectively. Co nclusions: Intravenacaval membrane oxygen and carbon dioxide removal c an provide partial respiratory support during severe respiratory failu re and permit reductions in the level of mechanical ventilator support , with an acceptable safety profile.