High-flow Nasal Cannula Oxygen Therapy Versus Noninvasive Ventilation For Patients With Acute Type Ⅱ Respiratory Failure:A Randomized Controlled Trial Of Non-inferiority

[Background]Type II respiratory failure with hypoxemia and hypercapnia,is a common critical case of emergency.So far,the guidelines recommend non-invasive ventilation（NIV）as a first-line respiratory support method for type II respiratory failure,but some patients with NIV intolerance and result in treatment failure,and some patients have contraindications for NIV treatment,which results in the application of NIV being restricted to some extent.At present,there is no ideal alternative method.High flow nasal cannula oxygen therapy（HFNC）is a fresh ilk of oxygen therapy in recent years which has unique physiological characteristics and advantages.Compared with NIV,it has certain advantages in tolerance and comfort.HFNC has been proved to have a good clinical effect on type I respiratory failure,and its research in COPD has gradually increased.However,the efficacy of HFNC in acute type II respiratory failure sicks caused by various causes remains to be further probed.[Objective]To parallel the efficacy of HFNC and NIV in the treatment of patients with multi-etiology acute type II respiratory failure through a single-center non-inferiority randomized controlled study,to clarify the feasibility of HFNC in the treatment of acute type II respiratory failure patients,and to bring evidence-based medical support for clinical application.[Methods]During the period from September 2021 to December 2022,respiratory supporters were required for emergency admission due to mild or moderate acute type II respiratory failure（Pa CO₂>50mm Hg with PH>7.25）,or because of acute type II respiratory failure treated with invasive mechanical ventilation,through spontaneous breathing trial proposed sequential breathing supporters,randomly assigned in HFNC and NIV groups.The primary outcome measure was the change of arterial blood partial pressure of carbon dioxide(Pa CO₂)from baseline to 24 hours of cure.The secondary outcome measures for the treatment of 2 hours,24 hours and 48 hours of blood gas analysis and vital signs,treatment failure rate（endotracheal intubation and ventilation,or respiratory support mode conversion）,dyspnea grade,comfort,number of airway intervention,respiratory support duration,ICU length of hospitalization,total length of hospitalization,and 28-day mortality,etc.[Results]Altogether 80 patients were randomly divided into two groups.After the second exclusion,69 patients were included in the analysis,including 33 in the HFNC group and36 in the NIV group.In terms of the etiology of type II respiratory failure,AECOPD ranked first,the second row of the lower respiratory tract infection,followed by heart failure.The mean change of Pa CO₂ level in the HFNC 24 hours treatment group from the baseline was-3.6±9.0 mm Hg,and the mean change of Pa CO₂ level in the NIV group was-3.2±14.5 mm Hg（P=0.881）.The absolute discrepancy between the two battery’s was-0.4 mm Hg（95%CI-5.9;6.9）,which did not reach the non-inferiority limit of 8mm Hg,so HFNC was non-inferiority than NIV（P=0.001）.The vital signs and other parameters of arterial blood gas analysis of patients in HFNC group and NIV group were similar after 2 hours,24 hours and 48 hours of treatment,with no statistical difference（P>0.05）.The treatment failure rate of HFNC group was 24.2%and 8.3%in NIV group.There was no significant difference between the two groups.NIV treatment intolerance was significantly higher than HFNC（P=0.006）.The 28-day mortality of patients in HFNC group and NIV group was 6.1%and 2.8%,respectively,there was no significant difference on statistics（P=0.504）.There was no significant difference between the two groups in respiratory support duration and ICU hospitalization duration（P>0.05）,but the total hospitalization duration of HFNC was 11.8（7.0,15.9）days,which was significantly extender than 7.8（5.8,11.9）days in NIV group（P=0.039）.Two groups of patients with dyspnea score was no statistical difference（P>0.05）.The comfort score of HFNC group on the first day and the third day was significantly higher than that of NIV group（P<0.0001）,while the facial lesions of NIV group were notable more than that of HFNC group on the third day of treatment（P=0.001）,and the quantity of airway nursing interventions in HFNC group was significantly lower than that of NIV group（P<0.01）.[Conclusion]For patients with acute mild or moderate type II respiratory failure,HFNC treatment for 24 hours is not inferior to NIV in reducing the level of arterial carbon dioxide partial pressure.HFNC treatment has higher comfort,better tolerance,less skin lesions and fewer airway nursing interventions,but HFNC is associated with longer hospitalization duration.In general,HFNC is an ideal alternative respiratory support method for NIV in patients with acute mild or moderate type II respiratory failure caused by multiple causes.