Respiratory Failure With Hypoxia

It is a prospective, controlled, single-center, observational, non-randomized study. The study is planned to include at least 500 patients 18 years old and older (300 patients in the training sample and 200 patients in the test sample. The study will include all patients requiring exclusion of the diagnosis of acute pulmonary embolism. Patients will be examined according to clinical guidelines to confirm the diagnosis of pulmonary embolism (laboratory, clinical and instrumental). During the course of the study, the authors of the work do not interfere with the scope of the examination, which is caried out on patients in accordance with clinical guidelines. All patients included in the study will undergo electrocardiogramm (ECG) in standart lead I for 1 minute, followed by spectral analysis of the obtained data, which will be stored at the Remote monitoring center of Sechenov University without being linked to the personal data of patients. A spectral analysis of the electrocardiogram will be performed using a continuous wavelet transformation. The result of this study will be the identification of ECG parameters that will correlate with pulmonary embolism.

To investigate the physiological effects of high positive end-expiratory pressure (PEEP) during noninvasive ventilation in patients with hypoxemic respiratory failure, and to elucidate the mechanisms underlying high PEEP-induced improvement in oxygenation.

The goal of this randomized trial is to compare four different flow-setting approaches for post-extubation use of high-flow nasal cannula (HFNC). Selecting the appropriate flow rate when initiating HFNC oxygen therapy is both crucial and challenging for clinicians, as the physiological benefits of HFNC depend significantly on the flow rate. To date, there are no guidelines or consensus on flow-rate setting and weaning for HFNC oxygen therapy. The investigators hypothesized that physiological marker-guided flow setting using peak tidal inspiratory flow (PTIF) or PaO₂/FiO₂ ratios lead to better extubation outcomes as compared to empirical flow setting of 40 L/min or 60 L/min. Participants will be randomly assigned to one of four study groups with different flow setting strategies summarized as follows: (1) Setting flow at 40 L/min, (2) Setting flow at 5 L/min above the peak tidal inspiratory flow, up to a maximum of 60 L/min. (3) Setting flow according to P/F ratio prior to extubation. Flow will be set at 60, 50 40 L/min if P/F ratio \<250 mmHg, 250-300 mmHg and \>300 mmHg, respectively. (4) Setting flow at 60 L/min.

High-flow nasal oxygen therapy (HFNO) is an innovative high-flow system that allows for delivering up to 60 liters/ min of heated and fully humidified gas with a fraction of inspired oxygen (FIO2) ranging between 21% and 100% . High-flow nasal oxygen therapy has become an increasingly popular choice of therapy due to the potential complications of invasive ventilation and the frequent uncomfortable or life-threatening adverse effects that are produced in non-invasive ventilation (NIV) . The HFNO allows the modification of only two variables: the percentage of oxygen being delivered and the rate of gas flow . Numerous well-designed studies have been conducted into the use of the HFNC in the treatment of critically ill patients, and HFNC is now widely used in the treatment of patients with various diagnoses including acute hypoxemic respiratory failure or acute respiratory distress syndrome (ARDS) , and is used in post-extubation treatment, post-cardiothoracic surgery respiratory distress , and respiratory compromise induced by heart failure . High-velocity nasal insufflation (HVNI) is a form of HFNC that utilizes a small bore nasal cannula to generate higher velocities of gas delivery than its counterparts using large bore HFNC. HVNI can accomplish a complete purge of extrathoracic dead space and may be able to provide ventilatory support in patients with acute hypercapnic respiratory failure in addition to oxygenation support. This study is necessary because, even though studies were being conducted to determine both the optimal technique for HFNO delivery and the clinical setting in which it is most useful, the best strategy for weaning from HVNI remains unknown. It has also not been established at what point a patient should be considered stable enough to attempt for withdrawing the HVNI