title: A randomized trial on subject tolerance and the adverse effects associated with higher- versus lower-flow oxygen through a standard nasal cannula.
abstract: OBJECTIVE
  Experts advocate the use of a standard nasal cannula to provide oxygen at flow rates of up to 15 L/minute during emergency intubation. However, because of concerns about potential patient discomfort, some providers avoid providing nasal cannula oxygen at flow rates greater than 6 L/minute. This trial is designed to determine the participants' ability to tolerate 10 minutes of nasal cannula oxygen at higher flow rates.
  
  
  METHODS
  This was a prospective, randomized, crossover trial of healthy volunteers at an emergency department in New Zealand. Participants were randomized to first receive either higher-flow (15 L/minute) or lower-flow (6 L/minute) nasal cannula oxygen for 10 minutes. After a 1-hour washout period, they received the alternate flow rate for 10 minutes. The primary outcome was the ability to tolerate 10 minutes of the nasal cannula oxygen at each flow rate. The secondary outcome was the difference in discomfort between the flow rates as measured on a 100-mm visual analog scale.
  
  
  RESULTS
  All 77 of the participants (100%) were able to tolerate 10 minutes at both flow rates. Participants rated the higher-flow nasal cannula oxygen as a mean of 25 mm (SD 20 mm) more uncomfortable than the lower-flow nasal cannula oxygen. One minute after the oxygen was discontinued, the mean difference in discomfort between the flow rates was a clinically insignificant 9.8 mm (SD 17 mm) more uncomfortable. There were no adverse events.
  
  
  CONCLUSIONS
  Participants were able to tolerate higher-flow nasal cannula oxygen for 10 minutes without difficulty. Higher-flow nasal cannula oxygen at 15 L/minute was associated with some discomfort, but the discomfort quickly dissipated and caused no adverse events.
authors.affiliation: Middlemore Hospital, Auckland, New Zealand; University of Auckland Medical School, Auckland, New Zealand. Electronic address: abrainard01@gmail.com.
authors.forename: Andrew
authors.initials: A
authors.lastname: Brainard
authors.affiliation: Middlemore Hospital, Auckland, New Zealand.
authors.forename: Danny
authors.initials: D
authors.lastname: Chuang
authors.affiliation: Middlemore Hospital, Auckland, New Zealand.
authors.forename: Irene
authors.initials: I
authors.lastname: Zeng
authors.affiliation: Middlemore Hospital, Auckland, New Zealand; University of Auckland Medical School, Auckland, New Zealand.
authors.forename: G Luke
authors.initials: GL
authors.lastname: Larkin
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002404:Catheterization / Q000009:adverse effects / Q000379:methods*; D018592:Cross-Over Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009666:Nose; D010100:Oxygen / Q000008:administration & dosage*; D010102:Oxygen Inhalation Therapy / Q000379:methods*; D010146:Pain / Q000209:etiology; D013997:Time Factors; D055815:Young Adult
chemical_list: D010100:Oxygen