BackgroundContinuous positive airway pressure (CPAP) has been increasingly deployed to manage patients with COVID-19 and acute respiratory failure, often for protracted periods. However, concerns about protracted CPAP have been raised. This study aimed to examine the use of CPAP for patients with COVID-19 and the outcomes after protracted use.MethodsThis was a national cohort study of all adults admitted to Scottish critical care units with COVID-19 from March 1, 2020 to December 25, 2021 who received CPAP. Protracted CPAP was defined as≥5 continuous days of CPAP. Outcomes included CPAP failure rate (institution of invasive mechanical ventilation [IMV] or death), mortality, and outcomes after institution of IMV. Multivariable logistic regression was performed to assess the impact of protracted CPAP on mortality after IMV.ResultsA total of 1961 patients with COVID-19 received CPAP for COVID-19 pneumonitis, with 733 patients (37.4%) receiving protracted CPAP. CPAP failure occurred in 891 (45.4%): 544 patients (27.7%) received IMV and 347 patients (17.7%) died in critical care without IMV. Hospital mortality rate was 41.3% for the population. For patients who subsequently commenced IMV, hospital mortality was 58.7% for the standard duration CPAP group and 73.9% for the protracted duration CPAP group (P=0.003); however, there was no statistical difference in hospital mortality after adjustment for confounders (odds ratio 1.4, 95% confidence interval 0.84–2.33,P=0.195).ConclusionsProtracted CPAP was used frequently for managing patients with COVID-19. Whilst it was not associated with worse outcomes for those patients who subsequently required IMV, this might be due to residual confounding and differences in processes of care.