Impact of high-flow oxygen therapy via high velocity nasal insufflation on diaphragmatic thickening fraction in healthy subjects

Objective: The primary objective of this study was to evaluate the impact of high-flow nasal cannula oxygen therapy [HFNC] on the diaphragm thickening fraction.

Design: Prospective, descriptive, cohort study SETTING: The study was conducted in the Physiology and Respiratory Care Laboratory, Intensive Care Unit, Hospital Británico de Buenos Aires.

Participants: Thirteen healthy subjects >18 years old INTERVENTIONS: High-flow nasal cannula oxygen therapy MAIN VARIABLES OF INTEREST: Demographic data (age and gender), anthropometric data (weight, height, and body mass index), and clinical and respiratory variables (Diaphragm thickening fraction [DTf], esophageal pressure swing, respiratory rate [RR], esophageal pressure-time product per minute [PTPes/min]).

Results: Median DTf decreased significantly as flow increased (p < 0.05). The baseline DTf measurement was 21.4 %, 18.3 % with 20 L/m, and 16.4 % with 40 L/m. We also observed a significant decrease in RR as flow increased in HFNC (p < 0.05). In the 8 subjects with recordings, the PTPes/min was 81.3 (±30.8) cmH2O/sec/min and 64.4 (±25.3) cmH₂O/sec/min at baseline and 40 L/m respectively (p = 0.044).

Conclusions: The use of high-flow oxygen therapy through nasal cannula of HFNC in healthy subjects decreases the DTf and RR in association with increased flow. In addition, the use of 40 L/m flow may reduce the muscular work associated with respiration.