title: Changes in respiratory elastance after deep inspirations reflect surface film functionality in mice with acute lung injury.
abstract: Pulmonary surfactant reduces surface tension in the lung and prevents alveolar collapse. Following a deep inspiration (DI), respiratory elastance first drops then gradually increases due to surface film and tissue viscoelasticity. In acute lung injury (ALI), this increase is faster and governed by alveolar collapse due to increased surface tension. We hypothesized that the rate of increase in elastance reflects the deficiency of surfactant in the lung. To test this, mice were ventilated before (baseline) and after saline lavage obtained by injecting 0.8 ml and withdrawing 0.7 ml fluid (severe ALI) or injecting 0.1 ml (mild ALI). After two DIs, elastance was tracked for 10 min followed by a full lavage to assess surfactant proteins B (SP-B) and C (SP-C) content. Following 2 DIs, the increases in elastance during 10 min ventilation (ΔH) were 3.60 ± 0.61, 5.35 ± 1.04, and 8.33 ± 0.84 cmH2O/ml in baseline mice and mice with mild and severe ALI, respectively (P < 0.0001). SP-B and SP-C in the lavage fluid dropped by 32.4% and 24.9% in the mild and 50.4% and 39.6% in the severe ALI, respectively. Furthermore, ΔH showed a strong negative correlation with both SP-B (r(2) = 0.801) and SP-C (r(2) = 0.810) content. The ΔH was, however, much smaller when the lavage fluid also contained exogeneous SP-B and SP-C. Thus ΔH can be interpreted as an organ level measure of surface film functionality in lavage-induced ALI in mice. This method could prove useful in clinical situations such as diagnosing surfactant problems, monitoring recovery from lung injury or the effectiveness of surfactant therapy.
authors.affiliation: Department of Biomedical Engineering, Boston University, Boston, Massachusetts.
authors.forename: Ayuko
authors.initials: A
authors.lastname: Takahashi
authors.affiliation: Department of Biomedical Engineering, Boston University, Boston, Massachusetts bsuki@bu.edu.
authors.forename: Erzsébet
authors.initials: E
authors.lastname: Bartolák-Suki
authors.affiliation: Department of Biomedical Engineering, Boston University, Boston, Massachusetts.
authors.forename: Arnab
authors.initials: A
authors.lastname: Majumdar
authors.affiliation: Department of Biomedical Engineering, Boston University, Boston, Massachusetts.
authors.forename: Béla
authors.initials: B
authors.lastname: Suki
mesh_terms: D055371:Acute Lung Injury / Q000503:physiopathology*; D000818:Animals; D055119:Elastic Modulus; D001239:Inhalation; D008170:Lung Compliance; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D011663:Pulmonary Surfactants / Q000737:chemistry / Q000378:metabolism*; D015656:Respiratory Mechanics; D013500:Surface Tension; D014783:Viscosity
chemical_list: D011663:Pulmonary Surfactants
keywords: acute lung injury; elastance; surfactant protein B; surfactant protein C