Heated and Humidified High-Flow Oxygen Therapy Reduces Discomfort During Hypoxemic Respiratory Failure

BACKGROUND: Non-intubated critically ill patients are often treated by high-flow oxygen for acute respiratory failure. There is no current recommendation for humidification of oxygen devices. METHODS: We conducted a prospective randomized trial with a final crossover period to compare nasal airway caliber and respiratory comfort in patients with acute hypoxemic respiratory failure receiving either standard oxygen therapy with no humidification or heated and humidified high-flow oxygen therapy (HHFO2) in a medical ICU. Nasal airway caliber was measured using acoustic rhinometry at baseline, after 4 and 24 hours (H4 and 1124), and 4 hours after crossover (H28). Dryness of the nose, mouth, and throat was auto-evaluated and assessed blindly by an otorhinolaryngologist. After the crossover, the subjects were asked which system they preferred. RESULTS: Thirty subjects completed the protocol and were analyzed. Baseline median oxygen flow was 9 and 12 L/min in the standard and HHFO2 groups, respectively (P = .21). Acoustic rhinometry measurements showed no difference between the 2 systems. The dryness score was significantly lower in the HHFO2 group at H4 (2 vs 6, P = .007) and H24 (0 vs 8, P = .004). During the crossover period, dryness increased promptly after switching to standard oxygen and decreased after switching to HHFO2 (P = .008). Sixteen subjects (53%) preferred HHFO2 (P = .01), especially those who required the highest flow of oxygen at admission (P = .05). CONCLUSIONS: Upper airway caliber was not significantly modified by HHFO2, compared to standard oxygen therapy, but HHFO2 significantly reduced discomfort in critically ill patients with respiratory failure. The system is usually preferred over standard oxygen therapy.