Author/Authors :
Lee, Dong Hyun Department of Pulmonology and Intensive Care Medicine - Dong-A University Hospital - Dong-A University College of Medicine - Busan, Korea , Kim, Eun Young Department of Pulmonary and Critical Care Medicine - Asan Medical Center - University of Ulsan College of Medicine - Seoul, Korea , Seo, Ga Jin Department of Pulmonary and Critical Care Medicine - Asan Medical Center - University of Ulsan College of Medicine - Seoul, Korea , Suh, Hee Jung Department of Pulmonary and Critical Care Medicine - Asan Medical Center - University of Ulsan College of Medicine - Seoul, Korea , Huh, Jin Won Department of Pulmonary and Critical Care Medicine - Asan Medical Center - University of Ulsan College of Medicine - Seoul, Korea , Hong, Sang-Bum Department of Pulmonary and Critical Care Medicine - Asan Medical Center - University of Ulsan College of Medicine - Seoul, Korea , Koh, Younsuck Department of Pulmonary and Critical Care Medicine - Asan Medical Center - University of Ulsan College of Medicine - Seoul, Korea , Lim, Chae-Man Department of Pulmonary and Critical Care Medicine - Asan Medical Center - University of Ulsan College of Medicine - Seoul, Korea
Abstract :
Background: High flow nasal cannula (HFNC) is known to increase global ventilation volume in healthy subjects. We sought to investigate the effect of HFNC on global and regional ventilation patterns in patients with hypoxia.
Methods: Patients were randomized to receive one of two oxygen therapies in sequence: nasal cannula (NC) followed by HFNC or
HFNC followed by NC. Global and regional ventilation was assessed using electric impedance tomography.
Results: Twenty-four patients participated. Global tidal variation (TV) in the lung was higher during HFNC (NC, 2,241 ± 1,381 arbitrary
units (AU); HFNC, 2,543 ± 1,534 AU; P < 0.001). Regional TVs for four iso-gravitational quadrants of the lung were also all higher during
HFNC than NC. The coefficient of variation for the four quadrants of the lung was 0.90 ± 0.61 during NC and 0.77 ± 0.48 during HFNC
(P = 0.035). Within the four gravitational layers of the lung, regional TVs were higher in the two middle layers during HFNC when compared to NC. Regional TV values in the most ventral and dorsal layers of the lung were not higher during HFNC compared with NC. The
coefficient of variation for the four gravitational layers of the lung were 1.00 ± 0.57 during NC and 0.97 ± 0.42 during HFNC (P = 0.574).
Conclusions: In patients with hypoxia, ventilation of iso-gravitational regions of the lung during HFNC was higher and more homogenized compared with NC. However, ventilation of gravitational layers increased only in the middle layers. (Clinical trials registration
number: NCT02943863).
