AUTHOR=Wittenstein Jakob , Scharffenberg Martin , Yang Xiuli , Bluth Thomas , Kiss Thomas , Schultz Marcus J. , Rocco Patricia R. M. , Pelosi Paolo , Gama de Abreu Marcelo , Huhle Robert 

TITLE=Distribution of transpulmonary pressure during one-lung ventilation in pigs at different body positions

JOURNAL=Frontiers in Physiology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2023.1204531

DOI=10.3389/fphys.2023.1204531

ISSN=1664-042X

ABSTRACT=<p><bold>Background</bold>. Global and regional transpulmonary pressure (P<sub>L</sub>) during one-lung ventilation (OLV) is poorly characterized. We hypothesized that global and regional P<sub>L</sub> and driving P<sub>L</sub> (ΔP<sub>L</sub>) increase during protective low tidal volume OLV compared to two-lung ventilation (TLV), and vary with body position.</p><p><bold>Methods</bold>. In sixteen anesthetized juvenile pigs, intra-pleural pressure sensors were placed in ventral, dorsal, and caudal zones of the left hemithorax by video-assisted thoracoscopy. A right thoracotomy was performed and lipopolysaccharide administered intravenously to mimic the inflammatory response due to thoracic surgery. Animals were ventilated in a volume-controlled mode with a tidal volume (V<sub>T</sub>) of 6 mL kg<sup>−1</sup> during TLV and of 5 mL kg<sup>−1</sup> during OLV and a positive end-expiratory pressure (PEEP) of 5 cmH<sub>2</sub>O. Global and local transpulmonary pressures were calculated. Lung instability was defined as end-expiratory P<sub>L</sub>&lt;2.9 cmH<sub>2</sub>O according to previous investigations. Variables were acquired during TLV (TLVsupine), left lung ventilation in supine (OLVsupine), semilateral (OLVsemilateral), lateral (OLVlateral) and prone (OLVprone) positions randomized according to Latin-square sequence. Effects of position were tested using repeated measures ANOVA.</p><p><bold>Results</bold>. End-expiratory P<sub>L</sub> and ΔP<sub>L</sub> were higher during OLVsupine than TLVsupine. During OLV, regional end-inspiratory P<sub>L</sub> and ΔP<sub>L</sub> did not differ significantly among body positions. Yet, end-expiratory P<sub>L</sub> was lower in semilateral (ventral: 4.8 ± 2.9 cmH<sub>2</sub>O; caudal: 3.1 ± 2.6 cmH<sub>2</sub>O) and lateral (ventral: 1.9 ± 3.3 cmH<sub>2</sub>O; caudal: 2.7 ± 1.7 cmH<sub>2</sub>O) compared to supine (ventral: 4.8 ± 2.9 cmH<sub>2</sub>O; caudal: 3.1 ± 2.6 cmH<sub>2</sub>O) and prone position (ventral: 1.7 ± 2.5 cmH<sub>2</sub>O; caudal: 3.3 ± 1.6 cmH<sub>2</sub>O), mainly in ventral (<italic>p</italic> ≤ 0.001) and caudal (<italic>p</italic> = 0.007) regions. Lung instability was detected more often in semilateral (26 out of 48 measurements; <italic>p</italic> = 0.012) and lateral (29 out of 48 measurements, <italic>p</italic> &lt; 0.001) as compared to supine position (15 out of 48 measurements), and more often in lateral as compared to prone position (19 out of 48 measurements, <italic>p</italic> = 0.027).</p><p><bold>Conclusion</bold>. Compared to TLV, OLV increased lung stress. Body position did not affect stress of the ventilated lung during OLV, but lung stability was lowest in semilateral and lateral decubitus position.</p>