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 24 h 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.