Technological Aspects and Safe Use of Noninvasive Mechanical Ventilation Devices: Key Technical and Practical Recommendations

Abstract

When ventilating patients noninvasively, it is important to employ ventilators that generate high flow rates. The flow is necessary to compensate for the leakage due to the mask, to avoid CO₂-rebreathing, and to handle the high flow that may be generated by spontaneously breathing patients, especially in case of acute respiratory failure. Turbine-driven ventilators are optimized to meet these criteria. Two different noninvasive ventilation (NIV) systems are available: one uses a breathing circuit with an integrated expiratory valve (active or passive), which requires a non-vented mask, and the other uses a breathing circuit without an expiratory valve, which requires a vented mask. A specialized “NIV team” is recommended to avoid misconnections. A higher oxygen delivery is necessary when patients are ventilated with NIV compared with spontaneous breathing. When the flow of the spontaneous breathing is lower than the flow generated by NIV, oxygen is diluted by the ambient air, which reduces the hemoglobin oxygen saturation. Therefore, an increase of the oxygen flow during NIV is often necessary. In conclusion, patients with severe hypoxemia who are ventilated with NIV require an optimal medical surveillance.