On adjusting measurements of airway responsiveness for lung size and airway caliber.

Considerable controversy exists over the influence of baseline airway caliber on indexes of bronchial responsiveness in asthma. To directly investigate this, we used inhaled methacholine to alter baseline airway caliber to determine whether this altered the airway response to subsequent bronchoprovocation with inhaled histamine. Seventeen stable asthmatic subjects were studied; their median age was 22 yr, baseline forced expiratory volume in 1 s (FEV1) was 101.5 +/- 3.7% (SE) predicted, and geometric mean provocative concentration of inhaled methacholine causing a 20% fall in FEV1 (PC20) was 0.87 mg/ml. Initially the time course of bronchoconstriction to inhaled methacholine was determined. Subsequently the airway response to inhaled histamine administered as a single concentration was determined, both before and after reductions in baseline FEV1 by saline or methacholine of 0, 15, 25, and 35%, on 4 separate days. Altering baseline airway caliber had no effect on the subsequent response of the airways to inhaled histamine when calculated as percent fall from the new baseline. The power of the study to detect an effect of altering baseline FEV1 on the measured PC20 histamine of 0.5 doubling dilutions was > 55%, and the power to detect an effect of 1.0 doubling dilutions was > 98%.

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Beta-adrenergic blockade in ponies with recurrent obstructive pulmonary disease

Journal of Applied Physiology ◽

10.1152/jappl.1988.64.6.2324 ◽

1988 ◽

Vol 64 (6) ◽

pp. 2324-2328 ◽

Cited By ~ 10

Author(s):

J. S. Scott ◽

R. V. Broadstone ◽

F. J. Derksen ◽

N. E. Robinson

Keyword(s):

Airway Obstruction ◽

Clinical Remission ◽

Dynamic Compliance ◽

Airway Responsiveness ◽

Adrenergic System ◽

Adrenergic Blockade ◽

Recurrent Airway Obstruction ◽

Beta Adrenergic ◽

Obstructive Pulmonary Disease ◽

Airway Caliber

Ponies with recurrent airway obstruction have hyperresponsive airways during acute disease exacerbations but not during clinical remission. We examined the effect of beta-adrenergic blockade with propranolol on airway responsiveness to aerosol histamine in six ponies with recurrent airway obstruction and six age- and gender-matched controls. Measurements were made with principal ponies in clinical remission (period A) and during an acute period of airway obstruction (period B). beta-Adrenergic blockade did not change airway responsiveness, dynamic compliance (Cdyn), or pulmonary resistance (RL) in either group of ponies at period A or in the control ponies at period B. In principal ponies at period B, propranolol significantly increased RL but was without effect on Cdyn or airway responsiveness. We conclude that the beta-adrenergic system is involved in the control of central airway caliber in principal ponies at period B but that this system does not seem to be involved in the mechanism of airway hyperresponsiveness to histamine.

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Increase in Airway Responsiveness and Effect of Deep Inhalation on Airway Caliber in Allergen-induced Asthma: Relationship to the Late-Phase Response

American Review of Respiratory Disease ◽

10.1164/ajrccm/146.1.127 ◽

1992 ◽

Vol 146 (1) ◽

pp. 127-131 ◽

Cited By ~ 8

Author(s):

Benedetto Violante ◽

Riccardo Pellegrino ◽

Emanuele Crimi ◽

Vito Brusasco

Keyword(s):

Late Phase ◽

Airway Responsiveness ◽

Phase Response ◽

Airway Caliber

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Comparison of the intensity and duration of effects of inhaled bitolterol and albuterol on airway caliber and airway responsiveness to histamine

Journal of Allergy and Clinical Immunology ◽

10.1016/0091-6749(90)90049-a ◽

1990 ◽

Vol 85 (6) ◽

pp. 1043-1049 ◽

Cited By ~ 3

Author(s):

James B. Harris ◽

Richard C. Ahrens ◽

Gary Milavetz ◽

Linda Annis ◽

Rebecca Ries ◽

...

Keyword(s):

Airway Responsiveness ◽

Airway Caliber

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Effect of transpulmonary pressure on airway diameter and responsiveness of immature and mature rabbits

Journal of Applied Physiology ◽

10.1152/jappl.2000.89.4.1584 ◽

2000 ◽

Vol 89 (4) ◽

pp. 1584-1590 ◽

Cited By ~ 22

Author(s):

X. Shen ◽

R. Ramchandani ◽

B. Dunn ◽

R. Lambert ◽

S. J. Gunst ◽

...

Keyword(s):

Transpulmonary Pressure ◽

Airway Responsiveness ◽

Tantalum Powder ◽

Airway Narrowing ◽

Airway Caliber ◽

Lung Resistance ◽

The Relationship

We previously demonstrated that airway responsiveness is greater in immature than in mature rabbits; however, it is not known whether there are maturational differences in the effect of transpulmonary pressure (Ptp) on airway size and airway responsiveness. The relationship between Ptp and airway diameter was assessed in excised lungs insufflated with tantalum powder. Diameters of comparable intraparenchymal airway segments were measured from radiographs obtained at Ptp between 0 and 20 cmH2O. At Ptp > 8 cmH2O, the diameters were near maximal in both groups. With diameter normalized to its maximal value, changing Ptp between 8 and 0 cmH2O resulted in a greater decline of airway caliber in immature than mature airways. The increases in lung resistance (Rl) in vivo at Ptp of 8, 5, and 2 cmH2O were measured during challenge with intravenous methacholine (MCh: 0.001–0.5 mg/kg). At Ptp of 8 cmH2O, both groups had very small responses to MCh and the maximal fold increases in Rl did not differ (1.93 ± 0.29 vs. 2.23 ± 0.19). At Ptp of 5 and 2 cmH2O, the fold increases in Rl were greater for immature than mature animals (13.19 ± 1.81 vs. 3.89 ± 0.37) and (17.74 ± 2.15 vs. 4.6 ± 0.52), respectively. We conclude that immature rabbits have greater airway distensibility and this difference may contribute to greater airway narrowing in immature compared with mature rabbits.

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