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.