Acute Hypoxic Respiratory Failure

The purpose of this clinical trial is to determine the best initial non-invasive respiratory support (NIRS) strategy for adults who present to the emergency department with acute hypoxemic respiratory failure, a condition in which blood oxygen levels are dangerously low and require urgent treatment. This study compares two commonly used non-invasive respiratory support strategies to evaluate their effectiveness and safety, based on important patient outcomes during hospitalization, including survival, the need for invasive mechanical ventilation, and the duration of respiratory support. Participants will be randomly assigned (with an equal chance) to receive one of the following treatments: * Non-Invasive Positive Pressure Ventilation (NIPPV): Oxygen delivered under pressure through a face mask. * High-Flow Nasal Oxygen (HFNO): Oxygen delivered at high-flow through a specially designed nasal cannula placed in the nostrils. Researchers will compare the two treatment strategies using a hierarchical assessment of major pulmonary outcomes, including: * Hospital survival * Days on mechanical ventilation * Duration of non-invasive respiratory support As part of the study, researchers will collect: * Blood and urine samples * Physiologic measurements (such as chest movement measured through sensors placed on the skin) * Information from participants' medical records

A multimodal educational intervention to target an oxygen saturation target range (SpO2 90-96%) will reduce ventilator length of stay and reduce occult hypoxemia by increased awareness and adherence to a designated oxygen saturation target range.

The Inspiratory effort-Targeted Pressure Support Ventilation (IT-PSV) is a cluster randomized controlled trial. Its main aim is to determine whether an inspiratory effort-targeted pressure support setting strategy, compared to the traditional tidal volume and respiratory rate target, can improve clinical outcomes in adult participants undergoing pressure support ventilation. The investigators propose a physiological-oriented assisted ventilation management that, if found effective, could potentially change the clinical practice for mechanical ventilation.

Pressure support ventilation (PSV) is one of the most frequently used ventilator modes in the intensive care unit (ICU). The successful implementation of PSV depends on matching the patient's inspiratory effort with the ventilator support. In clinical practice, the pressure support level is usually set and adjusted according to tidal volume (VT) and respiratory rate (RR). However, these parameters may not fully represent the patient's effort. Previous studies have shown that pressure muscle index (PMI), which is measured as the difference between the peak and plateau airway pressure during an end-inspiratory airway occlusion, could reliably determine the low and high inspiratory effort during PSV. However, the comparative effectiveness of these two pressure support level setting strategies remains uncertain. Our aim is to explore clinical and implementation factors relevant to a future definitive randomized controlled trial to evaluate PMI - and VT/RR - pressure support level setting strategies. The Inspiratory effort-targeted pressure support ventilation pragmatic pilot trial will test clinician adherence and to explore clinical outcomes. Two centers are included in a pragmatic sequential cluster crossover pilot trial. We enrolled all eligible adults with acute respiratory failure requiring mechanical ventilation admitted to ICU. The pressure support level setting strategy was assigned according to the epoch. The first trial epoch will be assigned to VTRR - pressure support level setting strategy for 4 weeks. The washout week between the two epochs will be 4 weeks. Then sequentially, it will be crossed over to PMI - pressure support level setting strategy for 4 weeks. * In the VT/RR-targeted group, the pressure support is adjusted to obtain a VT between 6 and 8 ml/kg PBW and RR between 20 and 35 breaths/min until day 28 or death or performance of spontaneous breathing trial (SBT). * In the PMI-targeted group, the pressure support is adjusted according to PMI between 0 and 2 cmH2O until day 28 or death or performance of SBT. We will also survey clinicians to understand potential facilitators and barriers to conducting a definitive randomized trial.