AUTHOR=Fahlman Andreas , Loring Stephen H. , Johnson Shawn P. , Haulena Martin , Trites Andrew W. , Fravel Vanessa A. , Van Bonn William G. 

TITLE=Inflation and deflation pressure-volume loops in anesthetized pinnipeds confirms compliant chest and lungs

JOURNAL=Frontiers in Physiology

VOLUME=5

YEAR=2014

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2014.00433

DOI=10.3389/fphys.2014.00433

ISSN=1664-042X

ABSTRACT=<p>We examined structural properties of the marine mammal respiratory system, and tested Scholander's hypothesis that the chest is highly compliant by measuring the mechanical properties of the respiratory system in five species of pinniped under anesthesia (Pacific harbor seal, <italic>Phoca vitulina;</italic> northern elephant seal, <italic>Mirounga angustirostris</italic>; northern fur seal <italic>Callorhinus ursinus</italic>; California sea lion, <italic>Zalophus californianus</italic>; and Steller sea lion, <italic>Eumetopias jubatus</italic>). We found that the chest wall compliance (C<sub>CW</sub>) of all five species was greater than lung compliance (airways and alveoli, C<sub>L</sub>) as predicted by Scholander, which suggests that the chest provides little protection against alveolar collapse or lung squeeze. We also found that specific respiratory compliance was significantly greater in wild animals than in animals raised in an aquatic facility. While differences in ages between the two groups may affect this incidental finding, it is also possible that lung conditioning in free-living animals may increase pulmonary compliance and reduce the risk of lung squeeze during diving. Overall, our data indicate that compliance of excised pinniped lungs provide a good estimate of total respiratory compliance.</p>