TY - JOUR
T1 - Effect of high-flow nasal cannula and body position on end-expiratory lung volume: A cohort study using electrical impedance tomography
AU - Riera, Jordi
AU - Pérez, Purificación
AU - Cortés, Jordi
AU - Roca, Oriol
AU - Masclans, Joan Ramon
AU - Rello, Jordis
PY - 2013/4/1
Y1 - 2013/4/1
N2 - BACKGROUND: Electrical impedance tomography measures changes in lung impedance, which are mainly related to changes in lung volume. We used electrical impedance tomography to investigate the effects of high-flow nasal cannula (HFNC) and body position on global and regional end-expiratory lung impedance variation (ΔEELI). METHODS: Prospective study with 20 healthy adults. Two periods were defined: the first in supine position and the second in prone position. Each period was divided into 3 phases. In the first and the third phases the subjects were breathing ambient air, and in the second HFNC was implemented. Four regions of interest were defined: 2 ventral and 2 dorsal. For each respiratory cycle, global and regional ΔEELI were measured by electrical impedance tomography and were expressed as a function of the tidal variation of the first stable respiratory cycle (units). RESULTS: HFNC increased global EELI by 1.26 units (95% CI 1.20-1.31, P<.001) in supine position, and by 0.87 units (95% CI 0.82-0.91, P<.001) in prone position. The distribution of ΔEELI was homogeneous in prone position, with no difference between ventral and dorsal lung regions (-0.01 units, 95% CI -0.01 to 0, P=.18), while in supine position a significant difference was found (0.22 units, 95% CI 0.21-0.23, P<.001) with increased EELI in ventral areas. CONCLUSIONS: HFNC increased global EELI in our population, regardless of body position, suggesting an increase in functional residual capacity. Prone positioning was related to a more homogeneous distribution of ΔEELI, while in supine position ΔEELI was higher in the ventral lung regions. © 2013 Daedalus Enterprises.
AB - BACKGROUND: Electrical impedance tomography measures changes in lung impedance, which are mainly related to changes in lung volume. We used electrical impedance tomography to investigate the effects of high-flow nasal cannula (HFNC) and body position on global and regional end-expiratory lung impedance variation (ΔEELI). METHODS: Prospective study with 20 healthy adults. Two periods were defined: the first in supine position and the second in prone position. Each period was divided into 3 phases. In the first and the third phases the subjects were breathing ambient air, and in the second HFNC was implemented. Four regions of interest were defined: 2 ventral and 2 dorsal. For each respiratory cycle, global and regional ΔEELI were measured by electrical impedance tomography and were expressed as a function of the tidal variation of the first stable respiratory cycle (units). RESULTS: HFNC increased global EELI by 1.26 units (95% CI 1.20-1.31, P<.001) in supine position, and by 0.87 units (95% CI 0.82-0.91, P<.001) in prone position. The distribution of ΔEELI was homogeneous in prone position, with no difference between ventral and dorsal lung regions (-0.01 units, 95% CI -0.01 to 0, P=.18), while in supine position a significant difference was found (0.22 units, 95% CI 0.21-0.23, P<.001) with increased EELI in ventral areas. CONCLUSIONS: HFNC increased global EELI in our population, regardless of body position, suggesting an increase in functional residual capacity. Prone positioning was related to a more homogeneous distribution of ΔEELI, while in supine position ΔEELI was higher in the ventral lung regions. © 2013 Daedalus Enterprises.
KW - Body position
KW - Electrical impedance tomography
KW - High-flow nasal cannula
KW - Lung volume
KW - Oxygen therapy
KW - Prone position
U2 - 10.4187/respcare.02086
DO - 10.4187/respcare.02086
M3 - Article
VL - 58
SP - 589
EP - 596
JO - Respiratory Care
JF - Respiratory Care
SN - 0020-1324
IS - 4
ER -