Nasal high-flow compared to non-invasive ventilation in treatment of acute acidotic hypercapnic exacerbation of chronic obstructive pulmonary disease – a randomized controlled noninferiority trial (ELVIS)

Background: We designed a prospective, randomized, multi-centre, open label, non-inferiority trial to compare treatment failure in nasal NHF vs NIV in patients with acidotic hypercapnic AECOPD. Methods: The study was conducted in about 35 sites in Germany. Patients with hypercapnic AECOPD with respiratory acidosis (pH < 7.35) were randomized 1:1 to NIV or NHF. The primary outcome was the combined endpoint of intubation, treatment failure or death at 72 h. The switch from one to the other device marks a device failure but acts as a rescue treatment in absence of intubation criteria. Results: Due to recruitment difficulties, the study was terminated prematurely. A total of 76 patients were randomised, with 38 in each group. The mean success rate from the linear model for NIV patients was estimated to be 82% and 54%. The success rate for NIV was 28% higher than that of NHF (95% CI 6 to 51%), p = 0.96. The probability of switching devices within 72h was estimated to be 9% for NIV patients and 46% for NHF. The rate for NIV is −37% lower than that of NHF (95% CI −57 to − 16%). Conclusion: Slow recruitment means that robust conclusions cannot be made, but there are indications that NIV is superior to NHF in this setting, since it is common to switch from the NHF to the NIV device. These preliminary results must be augmented with an in-depth analysis regarding the causes for switching devices.