Reduction of ventilator settings allowed by intravenous oxygenator (IVOX) in ARDS patients

Abstract

Objective: To evaluate the possibility of reducing ventilator settings to "safe" levels by extrapulmonary gas exchange with IVOX in ARDS patients. Design: Uncontrolled open clinical study. Setting: Medical Intensive Care Unit of a University Hospital. Patients: 6 patients with ARDS who entered into IVOX phase II clinical trials. Interventions: The end-point of this study was to reduce ventilator settings from the initial values, recorded on the day 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 volume-controlled ventilation within the 24h before and after IVOX insertion. Comparison of the results achieved during these trials used wilcoxon test. Results: Before IVOX implantation reduction of ventilator settings was not possible in the 6 patients, despite a non-significant increase in PaO2/FIO2 was achieved. IVOX permitted significant decrease in PaCO2 (from 60.5±15 to 52±11 mmHg;p=0.02) before any modification of the ventilatory mode. After IVOX insertion, a significant decrease of the ventilator settings was performed: peak and mean airway pressures dropped from 44±10 to 36.8±6.7;p=0.02 and from 26.3±5.6 to 22.5±3.9 cmH2O;p=0.02, respectively. Concommitantly, PaCO2 remained unchanged and PaO2/FIO2 increased significantly from 93±28 to 117±52;p=0.04. The interruption of oxygen flow on IVOX was associated with a slight decrease of the oxygen variables. Tolerance of IVOX was satisfactory. However, a significant decrease 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, respectively) was observed. Conclusion: Gas exchange achieved by IVOX allowed reduction of ventilator settings in 6 ARDS patients in whom previous attempts have failed. CO2 removal by the device, may explain these results. Efficacy of IVOX on arterial oxygenation was uncertain. © 1995 Springer-Verlag.