Risk of Early Intubation and High-Flow Nasal Cannula Failure in Pneumonia: Pre-Treatment Predictors using Triage Data from a Retrospective COVID-19 Cohort

Background Despite high-flow nasal cannula (HFNC) having improved outcomes in acute hypoxemic respiratory failure (AHRF), identifying patients unlikely to benefit before therapy initiation remains crucial to avoid delays in invasive mechanical ventilation (IMV). The objective of this study is to describe the clinical characteristics and outcomes of patients with AHRF due to COVID-19 pneumonia, and to identify predictors of early IMV and HFNC failure. Methods We conducted a retrospective study of patients with AHRF secondary to COVID-19 pneumonia evaluated between March 2020 and February 2021. Clinical data were collected during the pre-treatment phase in the emergency department. Study groups included early IMV, HFNC success, and HFNC failure, according to outcomes. The inclusion of patients needing early IMV aimed to capture clinical profiles in which immediate intubation was deemed necessary on admission, precluding the safe initiation of HFNC. Prognostic factors were explored using univariate logistic regression analysis. Results The study enrolled 139 patients (62% male, aged 56 years). Among them, 75 required IMV, 43 in the early IMV group and 32 classified as HFNC failure. Early IMV was associated with age, male sex, SpO₂, PaO₂/FiO₂ ratio, albumin levels, respiratory rate, troponin, and pneumonia severity indices. HFNC failure was associated with age, prior conventional oxygen therapy flow rates, urea, BUN, low lymphocyte count, and symptoms duration. Conclusions Early clinical variables evaluated at triage can help predict the need for immediate IMV and HFNC failure, supporting timely clinical decision-making in patients with AHRF. Trial registration: not applicable.