Chest
Session 9Relationships Among Airway-Parenchymal Interactions, Lung Responsiveness, and Inflammation in Asthma: Giles F. Filley Lecture
Section snippets
Volume History Measurements
Over a wide range of circumstances, the effects of a DI, whether expressed as an isovolumic ratio (M/P ratio) of maximal flows on successively performed partial (P—ie, maneuvers begun from functional residual capacity) and maximal (M—ie, maneuvers begun from total lung capacity) expiratory flow volume curves or the ratio of specific conductance measured immediately after a DI to that measured just before, give equivalent results1 (Fig 1). Therefore no special distinction will be made between
MECHANISMS
Is there a single, encompassing hypothesis that can account for all of these phenomena? Preferential emptying of a fast compartment at the beginning of both the P and M maneuvers could explain decreasing ratios with worsening obstruction as seen in cystic fibrosis,14 but would not explain the rising ratios seen with induced obstruction, nor would it be compatible with the equivalency of M/P and before and after DI conductance ratios. Diminished degrees of airway-parenchymal interdependence due
TESTING THE RELATIVE HYSTERESIS ANALYSIS
Since airway size is a dependent variable, no direct or indirect measurement of airway size can tell you whether a change in volume history response is predominantly the result of a change in parenchymal or in airway hysteresis. To test the appropriateness of the analysis, a direct assessment of parenchymal hysteresis is needed. We have used quasistatic lung volume-transpulmonary pressure curves to assess parenchymal hysteresis and its acute changes.8 This is based on the premise that overall
CONCLUSIONS
The relationships among lung responsiveness, sites and mechanisms of responses, and effects of a DI on airway caliber could make volume history ratio assessment an interesting and perhaps valuable physiologic tool in both clinical and epidemiologic studies of asthma. In addition, increased insight into the phlogistic and physiologic aspects of the phenomena described should enhance our understanding of airway-parenchymal interactions in health and disease.
REFERENCES (19)
Physiological assessment of inflammation in the peripheral lung of asthmatic patients
Lung
(1990)- et al.
Effects of volume history during spontaneous and acutely induced obstruction in asthma
Am Rev Respir Dis
(1987) - et al.
et al The effects of deep inhalations on maximal expiratory flows during intensive treatment of spontaneous asthmatic episodes
Am Rev Respir Dis
(1989) - et al.
Responsiveness, inflammation and effects of deep breaths on obstruction in mild asthma
J Appl Physiol
(1989) Site and mechanism of obstruction and hyperresponsiveness in asthma
Am Rev Respir Dis
(1987)- et al.
Effect of lung volume, volume history and methacholine on tissue viscance in man
J Appl Physiol
(1989) - et al.
Bronchial responsiveness to methacholine and effects of respiratory maneuvers
J Appl Physiol
(1984) - et al.
Effects of deep inhalation in asthma: relative airway and parenchymal hysteresis
J Appl Physiol
(1985) - et al.
Relationship between quasistatic pulmonary hysteresis and airway narrowing in humans
J Appl Physiol
(1992)
Cited by (21)
Airway smooth muscle and bronchospasm: Fluctuating, fluidizing, freezing
2008, Respiratory Physiology and NeurobiologyAirway obstruction and chronic exertional dyspnoea in patients with persistent bronchial asthma
2000, Respiratory MedicineFrozen objects: Small airways, big breaths, and asthma
2000, Journal of Allergy and Clinical ImmunologyParenchymal mechanics and asthma
1995, ChestProtective effects and mechanisms of mogroside v on LPS-induced acute lung injury in mice
2014, Pharmaceutical Biology
Supported by grants from the National Heart, Lung, and Blood Institute, Bethesda, Md.