title: Nonlinearity of respiratory mechanics during bronchoconstriction in mice with airway inflammation.
abstract: Respiratory system resistance (R) and elastance (E) are commonly estimated by fitting the linear equation of motion P = EV + RV + P0 (Eq. 1) to measurements of respiratory pressure (P), lung volume (V), and flow (V). However, the respiratory system is unlikely to behave linearly under many circumstances. We determined the importance of respiratory system nonlinearities in two groups of mechanically ventilated Balb/c mice [controls and mice with allergically inflamed airways (ova/ova)], by assessing the impact of the addition of nonlinear terms (E2V2 and R2V(V)) on the goodness of model fit seen with Eq. 1. Significant improvement in fit (51.85 +/- 4.19%) was only seen in the ova/ova mice during bronchoconstriction when the E2V2 alone was added. An improvement was also observed with addition of the E2V2 term in mice with both low and high lung volumes ventilated at baseline, suggesting a volume-dependent nonlinearity of E. We speculate that airway closure in the constricted ova/ova mice accentuated the volume-dependent nonlinearity by decreasing lung volume and overdistending the remaining lung.
authors.affiliation: Vermont Lung Center, Department of Medicine, University of Vermont, Burlington 05405, USA. ssw6609739@cs.com
authors.forename: Scott
authors.initials: S
authors.lastname: Wagers
authors.forename: Lennart
authors.initials: L
authors.lastname: Lundblad
authors.forename: Henrique T
authors.initials: HT
authors.lastname: Moriya
authors.forename: Jason H T
authors.initials: JH
authors.lastname: Bates
authors.forename: Charles G
authors.initials: CG
authors.lastname: Irvin
mesh_terms: D000280:Administration, Inhalation; D000818:Animals; D001249:Asthma / Q000503:physiopathology*; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology / Q000276:immunology; D016084:Bronchoconstriction / Q000187:drug effects / Q000502:physiology; D002452:Cell Count; D004195:Disease Models, Animal; D005260:Female; D008176:Lung Volume Measurements; D016210:Methacholine Chloride / Q000008:administration & dosage; D051379:Mice; D008807:Mice, Inbred BALB C; D017711:Nonlinear Dynamics; D010047:Ovalbumin / Q000276:immunology; D011014:Pneumonia / Q000503:physiopathology*; D011175:Positive-Pressure Respiration; D012121:Respiration, Artificial; D015656:Respiratory Mechanics / Q000187:drug effects / Q000502:physiology
chemical_list: D016210:Methacholine Chloride; D010047:Ovalbumin