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 H2O, 2.58 ± 1.54 cm H2O, and 3.31 ± 1.05 cm H2O, 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)
Footnotes
- Correspondence: Rachael L Parke RN MHSc, Cardiothoracic and Vascular Intensive Care Unit, Auckland City Hospital, Private Bag 92024, Auckland 1010, New Zealand. E-mail: rparke{at}adhb.govt.nz.
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This study was partly supported by Fisher & Paykel Healthcare, which provides some funding to the Auckland District Health Board for the research nurse's salary in the Cardiothoracic and Vascular ICU, Auckland City Hospital, and which provided some of the supplies used in the study and paid for the statistical analysis. Michelle Eccleston is now employed as clinical research scientist by Fisher & Paykel Healthcare and is part of an employee-sharing arrangement.
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