Noninvasive ventilation (lecture)

Abstract

The lecture focuses on step by step respiratory therapy in patients with acute respiratory dysfunction. The first step in treating patients with acute respiratory dysfunction (in the absence of indications for invasive mechanical ventilation) is the use of high-flow oxygen therapy (HFOT) and noninvasive ventilation. In comparison with invasive ventilation, both methods have certain advantages. In particular, they do not result in ventilator-associated lung injury, ventilator-induced diaphragmatic dysfunction, ventilator-associated pneumonia. Noninvasive ventilation provides the specified FiO2 level in combination with moderate positive end-expiratory pressure (РЕЕР)/continuous positive airway pressure (СРАР) and inspiratory pressure. Unlike oxygenation through the face mask or nasal cannulas, it reduces the likelihood of expiratory closure of small airways, prevents alveolar collapse and the risk of atelectasis. The advantage of noninvasive ventilation over standard oxygen therapy through the face mask/nasal cannulas is that it provides a moderate level of РЕЕР/СРАР, which reduces pre- and post-load on the left ventricle. This is especially important in patients with acute left ventricular failure and/or pulmonary edema. One of the main conditions for adequate noninvasive ventilation is the consciousness of the person. The basis of the clinical effectiveness of HFOT is the ability to create a high gas flow rate (up to 60 l/min). Such a flow rate (which is equal to or even greater than the flow rate of the patient’s inhalation) minimizes the “mixing” of room air and allows maintaining a high level of FiO2. The ability of the step by step method to control the flow rate and temperature, accurate determination of FiO2 is crucially important. Modern HFOT systems have special contours of semipermeable materials that do not allow condensation and have original nasal or tracheostomic cannulas.