title: Heated and humidified high-flow oxygen therapy reduces discomfort during hypoxemic respiratory failure.
abstract: 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 H24), 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.
authors.affiliation: Service de Réanimation Médicale, Assistance Publique Hôpitaux de Paris, Hôpital Henri Mondor, Créteil, France. elise.cuquemelle@hmn.aphp.fr
authors.forename: Elise
authors.initials: E
authors.lastname: Cuquemelle
authors.forename: Tai
authors.initials: T
authors.lastname: Pham
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Papon
authors.forename: Bruno
authors.initials: B
authors.lastname: Louis
authors.forename: Pierre-Eric
authors.initials: PE
authors.lastname: Danin
authors.forename: Laurent
authors.initials: L
authors.lastname: Brochard
mesh_terms: D000208:Acute Disease; D000328:Adult; D000368:Aged; D003422:Critical Care; D018592:Cross-Over Studies; D005260:Female; D006358:Hot Temperature / Q000627:therapeutic use; D006801:Humans; D006813:Humidity; D000860:Hypoxia / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D009296:Nasal Cavity; D009297:Nasal Mucosa / Q000503:physiopathology; D010102:Oxygen Inhalation Therapy / Q000009:adverse effects / Q000379:methods*; D010146:Pain / Q000209:etiology; D057240:Patient Preference; D012131:Respiratory Insufficiency / Q000628:therapy*; D023842:Rhinometry, Acoustic; D016037:Single-Blind Method