Total and regional lung volume changes during high-frequency oscillatory ventilation (HFOV) of the normal lung.
The effect of high-frequency oscillatory ventilation (HFOV) settings on the distribution of lung volume (V(L)) with changes in mean airway pressure (Paw), frequency (f(R)) and tidal volume (V(T)) remains controversial. We used computer tomographic (CT) imaging to quantify the distribution of V(L) during HFOV compared to static continuous positive airway pressure (CPAP). In anesthetized, supine canines, CT imaging of the entire lung was performed during CPAP and HFOV at Paw of 5, 12.5 and 20 cm H(2)O, f(R)=5, 10, 15 Hz. We found small, statistically significant decreases compared with CPAP in total and regional V(L) during HFOV that were greatest at lower f(R) and Paw. Apex and base sub-volumes underwent changes comparable to the lung overall. Increases in f(R) were accompanied by increases in Pa(O)(2). These finding provide additional insight into the impact of HFOV settings on the distribution of V(L) and suggest that there is low risk of occult regional over-distention during HFOV in normal lungs.
Easley
R Blaine
RB
Department of Anesthesiology and Critical Care Medicine, The Johns Hopkins University, Baltimore, MD, United States. beasley@jhmi.edu
Lancaster
Christopher T
CT
Fuld
Matthew K
MK
Custer
Jason W
JW
Hager
David N
DN
Kaczka
David W
DW
Simon
Brett A
BA
D000818:Animals; D001703:Biophysics; D045422:Continuous Positive Airway Pressure; D004285:Dogs; D006612:High-Frequency Ventilation; D008168:Lung / Q000502:physiology*; D008176:Lung Volume Measurements / Q000379:methods; D011312:Pressure; D012123:Pulmonary Ventilation / Q000502:physiology*; D013990:Tidal Volume; D014057:Tomography, X-Ray Computed