Noninvasive ventilation(NIV) is an important treatment to the respiratory failure patients.The severe Corona Virus Disease-19(COVID-19) patients are incline to respiratory failure.The NIV may reduce the intubtion rate.This research was taken to investigate the factor to the success of the noninvasive ventilation to the COVID-19 patients with respiratory failure.

Noninvasive ventilation(NIV) is an important treatment to the respiratory failure patients.The severe Corona Virus Disease-19(COVID-19) patients are incline to respiratory failure.The NIV may reduce the intubtion rate.This research was taken to investigate the factor to the success of the noninvasive ventilation to the COVID-19 patients with respiratory failure.We wish to raise the success rate to COVID-19 patients with respiratory failure.More critically ill COVID-19 patients could avoid the intubtion.

Inclusion Criteria:

1. Shortness of breath, RR>30 times per minute;
2. At room air, SpO2 lower than 93%;
3. The partial pressure of Arterial blood oxygen (PaO2)/the fraction of inspired oxygen (FiO2) ≤ 300mmHg;
4. CT（computed tomography） chest imaging shows that lung damage develops significantly within 24 to 48 hours.

Exclusion Criteria:

1. Severe cardiovascular disease,
2. respiratory arrest,
3. cardiovascular instability (hypotension, arrhythmias, myocardial infarction),
4. change in mental status or patients who were uncooperative, high risk of aspiration, viscous or copious
5. secretions,
6. recent facial or gastroesophageal surgery,
7. craniofacial trauma, 8)fixed nasopharyngeal abnormalities,

9）burns, 10) extreme obesity.

respiratory failure patients with COVID-19

the IPD are going to share after the paper published.