Application of active subglottic airway humidification in intermittent subglottic secretion drainage in patients with tracheostomy: a randomized controlled trial

Background: Intermittent aspiration of subglottic secretions (IASS) is commonly used to alleviate retention on the cuff, but inappropriate subglottic secretion drainage may lead to adverse effects, and fewer studies have been conducted on active subglottic airway humidification to improve the safety and effectiveness of IASS. Methods: A randomized controlled trial was conducted from August 2023 to July 2024, involving 90 patients with flushable tracheostomy tubes: 48 patients received 30-min pre-drainage active humidification (intervention group), while 42 patients received sterile water flush (control group). The outcomes included vital signs, secretion viscosity, cuff pressure, inspired and exhaled tidal volume, catheter blockage, occult blood positivity, and the incidence of ventilator-associated pneumonia (VAP). Results: The control group demonstrated a higher incidence of occult blood positivity (23.81% vs. 8.33%), blockage rate of the drainage catheter (19.05% vs. 4.17%), and Δcuff pressure (2.90 ± 1.39 cmH2O vs. 1.48 ± 0.99 cmH2O), with all comparisons yielding p < 0.05. Furthermore, the reduction rate of the viscosity of subglottic secretion was lower in the control group than in the intervention group (9.52% vs. 64.58%, p < 0.01). Although ΔVTe and VTleak of the intervention group were significantly increased, no significant differences were observed in ΔSpO2, ΔPETCO2, or the incidence of VAP. Conclusion: Active subglottic airway humidification prior to IASS significantly reduces the positive rate of occult blood (OB) tests, the incidence of drainage catheter blockage, and secretion viscosity, with the exception of the incidence of VAP. It also stabilizes cuff pressure with minimal fluctuation. Although the intervention is associated with a decrease in exhaled tidal volume, it has no significant impact on pulse oxygen saturation or end-tidal carbon dioxide pressure. © The Author(s) 2025.