The effects of flow on airway pressure during nasal high-flow oxygen therapy

Abstract

Background: Nasal high-flow oxygen therapy increases the mean nasopharyngeal airway pressure in adults, but the relationship between flow and pressure is not well defined.

Objective: To determine the relationship between flow and pressure with the Optiflow nasal high-flow oxygen therapy system.

Methods: We invited patients scheduled for elective cardiac surgery to participate. Measurements were performed with nasal high-flow oxygen at flows of 30, 40, and 50 L/min, with the patient's mouth both open and closed. Pressures were recorded over one minute of breathing, and average flows were calculated via simple averaging.

Results: With the mouth closed, the mean ± SD airway pressures at 30, 40, and 50 L/min were 1.93 ± 1.25 cm H(2)O, 2.58 ± 1.54 cm H(2)O, and 3.31 ± 1.05 cm H(2)O, respectively. There was a positive linear relationship between flow and pressure.

Conclusions: The mean nasopharyngeal pressure during nasal high-flow oxygen increases as flow increases. Australian Clinical Trials Registry http://www.adhb.govt.nz/achicu/hot_2_airway_pressure.htm.