PREdicting Failure of Non-inVasIve Ventilatory Support Using Non-invaSIve mONitoring in Non-intubated Patients With Acute Hypoxemic Respiratory Failure or Post-extubation Failure. The PREVISION Study

This is a single-center, prospective, physiological study.

The study will enroll patient who has used either HFNC or NIV for the indications of 1. to prevent worsening acute hypoxemic respiratory failure or 2. to prevent reintubation. Once being confirmed to meet the inclusion criteria, the research team will apply the electrical impedance tomography (EIT) on the patient and start recording for 5-10 minutes as well as perform diaphragm and parasternal intercostal muscle ultrasound when the patient is using HFNC or NIV. The current HFNC or NIV setting, some lung mechanic's parameters (e.g. rapid shallow breathing trial (RSBI), negative airway pressure generated during the first 100 milisecond (P0.1), end-expiratory occlusion pressure(ΔPocc) derived from NIV machine), patient's characteristic, dyspnea scores (intensive care respiratory distress observation scale, IC-RDOS; work of breathing scale; self-report of dyspnea visual analog scale, D-VAS), ICU and hospital length of stay will be also collected.

The investigator will use EIT to visualize where air goes in the patient's lung and inspiratory muscle ultrasonography (diaphragm and parasternal intercostal muscle) to visualize the muscle activities when using HFNC or NIV. EIT is a measurement often used in the ICU since it allows easy visualization and is a non-invasive technique. The sensors measure electrical current changes during inspiration and expiration and will not cause any pain or radiation concerns. The EIT belt (3-cm diameter) will be placed around the chest without causing adverse event/discomfort/pain.

The duration of study will be approximately 30 minutes. The study will be conducted one time for one enrolled patient.

HFNC or NIV (device) failure is considered as either intubation/reintubation or death, whatever has come first. It will be followed up to 7 days.

The investigators will proceed with the measurements only with agreement from the clinical team. The investigators will analyze the data collected offline with a dedicated software afterwards.

After these study procedures are completed, data will also be collected from the participant's chart and combined with relevant information from the HFNC or NIV settings and vital functions. Confidentiality will be maintained throughout the entire study.

Time frame: The parameter is measured at the time of enrolment. Failure of HFNC or NIV is adjudicated at 7 days.

The primary endpoint is to assess regional ventilation distribution (%) when using HFNC or NIV to predict a device failure.

Time frame: The parameter is measured at the time of enrolment. Failure of HFNC or NIV is adjudicated at 7 days.

To assess ultrasound measurement of inspiratory muscle activity when using HFNC or NIV to predict a device failure.

Time frame: The parameter is measured at the time of enrolment. Failure of HFNC or NIV is adjudicated at 7 days.

To assess non-invasive respiratory - rapid shallow breathing index (RSBI) derived from NIV to predict a device failure.

Time frame: The parameter is measured at the time of enrolment. Failure of HFNC or NIV is adjudicated at 7 days.

To assess respiratory drive - using negative airway pressure generated during the first 100 millisecond (P0.1) in cmH2O to predict device failure.

Time frame: The parameter is measured at the time of enrolment. Failure of HFNC or NIV is adjudicated at 7 days.

To assess respiratory effort using end-expiratory airway occlusion pressure (ΔPocc) in cmH2O to predict device failure

Time frame: The parameter is measured at the time of enrolment. Failure of HFNC or NIV is adjudicated at 7 days.

To assess the level of dyspnea using intensive care respiratory distress observation scale (IC-RDOS) to predict a device failure. There is no minimum or maximum range depending on patient's heart rate, the higher score means worse outcome. When the score ≥ 2.4, it likely indicates clinically important dyspnea requiring clinical management.

Time frame: The parameter is measured at the time of enrolment. Failure of HFNC or NIV is adjudicated at 7 days.

To assess the work of breathing scale to predict a device failure. Minimum is 3 and maximum is 12, the higher score means worse outcome. When the score \> 4, it likely indicates severe respiratory distress.

Time frame: The parameter is measured at the time of enrolment. Failure of HFNC or NIV is adjudicated at 7 days.

To assess self-report of dyspnea visual analog scale (D-VAS) to predict a device failure. Minimum is 0 and maximum is 10, the higher score means worse outcome. When the score \> 3, it likely indicates dyspnea and being used for quality of palliative care unit

PREdicting Failure of Non-inVasIve Ventilatory Support Using Non-invaSIve mONitoring in Non-intubated Patients With Acute Hypoxemic Respiratory Failure or Post-extubation Failure: the PREVISION Study