REDUCTION OF VENTILATOR SETTINGS ALLOWED BY INTRAVENOUS OXYGENATOR (IVOX) IN ARDS PATIENTS

Objective: To evaluate the possibility of reducing ventilator settings to ''safe'' levels by extrapulmonary gas exchange with IVOX in ARDS p atients. Design: Uncontrolled open clinical study. Setting: Medical In tensive Care Unit of a University Hospital. Patients: 6 patients with ARDS who entered into IVOX phase II clinical trials. Interventions: Th e end-point of this study was to reduce ventilator settings from the i nitial values, recorded on the da of inclusion, to the following: peak inspiratory pressure < 40 cmH2O, mean airway pressure < 25 cmH2O and tidal volume < 10 ml/kg. Trials to achieve this goal were made on volu me-controlled ventilation within the 24 h before and after IVOX insert ion. Comparison of the results achieved during these trials used Wilco xon test. Results: Before IVOX implantation reduction of ventilator se ttings was not possible in the 6 patients, despite a non-significant i ncrease in PaO2/FIO2 was achieved. IVOX permitted significant decrease in PaCO2 (from 60.5 +/- 15 to 52 +/- 11 mmHg; p = 0.02) before any mo dification of the ventilatory mode. After IVOX insertion, a significan t decrease of the ventilator settings was performed: peak and mean air way pressures dropped from 44 +/- 10 to 36.8 +/- 6.7; p = 0.02 and fro m 26.3 +/- 5.6 to 22.5 +/- 3.9 cmH2O; p = 0.02, respectively. Concommi tantly, PaCO2 remained unchanged and PaO2/FIO2 increased significantly from 93 +/- 28 to 117 +/- 52; p = 0.04. The interruption of oxygen fl ow on IVOX was associated with a slight decrease of the oxygen variabl es. Tolerance of IVOX was satisfactory. However, a significant decreas e both in cardiac index and in pulmonary wedge pressures (from 4.5 +/- 1.2 to 3.4 +/- 9; p = 0.03 and from 16 +/- 5 to 11 +/- 2; p = 0.04, r espectively) was observed. Conclusion: Gas exchange achieved by IVOX a llowed reduction of ventilator settings in 6 ARDS patients in whom pre vious attempts have failed. CO2 removal by the device, may explain the se results. Efficacy of IVOX on arterial oxygenation was uncertain.