Assessment of heterogeneous airway constriction in dogs: a structure-function analysis

David W Kaczka; Robert H Brown; Wayne Mitzner

doi:10.1152/japplphysiol.90576.2008

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Assessment of heterogeneous airway constriction in dogs: a structure-function analysis

Journal article

Open access

Peer reviewed

Assessment of heterogeneous airway constriction in dogs: a structure-function analysis

David W Kaczka, Robert H Brown and Wayne Mitzner

Journal of applied physiology (1985), Vol.106(2), pp.520-530

02/2009

DOI: 10.1152/japplphysiol.90576.2008

PMCID: PMC2644239

PMID: 18927269

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Abstract

Obstructive lung diseases are often characterized by heterogeneous patterns of bronchoconstriction, although specific relationships between structural heterogeneity and lung function have yet to be established. We measured respiratory input impedance (Zrs) in eight anesthetized dogs using broadband forced oscillations at baseline and during intravenous methacholine (MCh) infusion. We also obtained high-resolution computed tomographic (HRCT) scans in 4 dogs and identified 20-30 individual airway segments in each animal. The Zrs spectra and HRCT images were obtained before and 5 min following a deep inspiration (DI) to 35 cmH(2)O. Each Zrs spectrum was fitted with two different models of the respiratory system: 1) a lumped airways model consisting of a single airway compartment, and 2) a distributed airways model incorporating a continuous distribution of airway resistances. For the latter, we found that the mean level and spread of airway resistances increased with MCh dose. Whereas a DI had no effect on average airway resistance during MCh infusion, it did increase the level of airway heterogeneity. At baseline and low-to-moderate doses of MCh, the lumped airways model was statistically more appropriate to describe Zrs in the majority of dogs. At the highest doses of MCh, the distributed airways model provided a superior fit in half of the dogs. There was a significant correlation between heterogeneity assessed with inverse modeling and the standard deviation of airway diameters obtained from HRCT. These data demonstrate that increases in airway heterogeneity as assessed with forced oscillations and inverse modeling can be linked to specific structural alterations in airway diameters.

Airway Resistance - drug effects

Bronchial Provocation Tests

Tomography, X-Ray Computed

Lung - diagnostic imaging

Lung - physiology

Dose-Response Relationship, Drug

Bronchoconstrictor Agents - administration & dosage

Animals

Bronchoconstriction - drug effects

Methacholine Chloride - administration & dosage

Models, Biological

Lung - drug effects

Dogs

Infusions, Intravenous

Respiratory Mechanics

Oscillometry

Details

Title: Subtitle: Assessment of heterogeneous airway constriction in dogs: a structure-function analysis
Creators: David W Kaczka - Department of Anesthesiology and Critical Care Medicine, The Johns Hopkins Hospital, Baltimore, MD 21287, USA. dkaczka1@jhmi.edu
Robert H Brown
Wayne Mitzner
Resource Type: Journal article
Publication Details: Journal of applied physiology (1985), Vol.106(2), pp.520-530
DOI: 10.1152/japplphysiol.90576.2008
PMID: 18927269
PMCID: PMC2644239
NLM abbreviation: J Appl Physiol (1985)
ISSN: 8750-7587
eISSN: 1522-1601
Publisher: United States
Grant note: P01 HL-010342 / NHLBI NIH HHS K08 HL-089227 / NHLBI NIH HHS
Language: English
Date published: 02/2009
Academic Unit: Roy J. Carver Department of Biomedical Engineering; Radiology; Anesthesia
Record Identifier: 9984007288202771

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