Airway Secretion Volume and Physiological Effects of High-Flow Nasal Cannula in Acute Respiratory Failure Because of Bronchiectasis

Background: Acute respiratory failure (ARF) in bronchiectasis is frequently accompanied by excessive airway secretions. High-flow nasal cannula (HFNC) delivers heated, humidified gas and may improve respiratory mechanics, but quantitatively measured secretion burden during HFNC in bronchiectasis-related ARF is poorly described. Methods: We conducted a prospective, single-center pilot cohort study in a respiratory intermediate care unit including adults with computed tomography-confirmed bronchiectasis admitted with ARF and treated with HFNC as first-line therapy. The primary outcome was cumulative secretion volume (operationally defined as supervised collection of expectorated sputum, with measures to minimize saliva contamination) during the first 3 days of HFNC exposure. Physiologic variables, gas exchange, dyspnea, and clinical outcomes were assessed descriptively. Results: Twenty-six subjects were enrolled (median age 67 years, 54% female), predominantly with moderate-to-severe bronchiectasis. Median cumulative secretion volume over 72 h was 510 mL (436-743), and daily secretion volume increased from Day 1 to Day 3 (P < .001). Breathing frequency, oxygenation, dyspnea (Borg scale), and selected gas-exchange variables changed significantly over time. No subject required escalation to noninvasive ventilation or endotracheal intubation. In-hospital mortality was 11.5% (3/26), occurring exclusively in subjects with preestablished do-not-intubate directives. Conclusions: In this pilot cohort of bronchiectasis-related ARF, structured quantification of secretion volume during HFNC was feasible and documented a large early secretion burden over 72 h. Given the uncontrolled design, these findings are descriptive and should not be interpreted as evidence of treatment effect.