Abbreviations: DI = discerning lung inflation; R = real part of impedance; Z = impedance Previously.

Abbreviations: DI = discerning lung inflation; R = real part of impedance; Z = impedance

Previously, we (1) have shown that peripheral resistance rises more in asthmatic controls than in nonasthmatic subjects following direct stimulation with staid dry air. To gain further insight into this answer we measured the input impedance (Z) of the lung periphery in rejoinder to methacholine by applying forced oscillations by the and of a wedged bronchoscope in asthmatic and nonasthmatic subjects

We used a computer-controll piston cross-examine (flexiVent; SCIREQ; Montreal, QU, Canada) to deliver a broad-band (ie, 05 to 20 Hz) oscillatory sweep along through the wedged bronchoscope during 8 s of apnea at functional residual capacity. press at the tip of the bronchoscope and deliquesce data were used to calculate Z Z was measured at baseline, following escalating doses of methacholine, following three unfathomable lung inflations (DIs), and, finally, following albuterol administration.

At baseline, the real part of Z (R) was elevated in the asthmatic controls (two subjects) compared to the nonasthmatic make liables (three subjects). Methacholine induced an increase in R at ,all frequencies in the two groups, but the responsiveness of the asthmatic enthralls was more than two orders of magnitude greater than that of the nonasthmatic exposes At higher doses of methacholine, R increased most numerous in the low-frequency range, suggesting a predominantly tissue answer Following three DIs, the low-frequency R dropp more than its higher frequent occurrence component, implying a substantial tissue general intent of DI. Albuterol brought R back toward baseline at all frequencies.

These preliminary data propose the following: (1) the lung periphery of asthmatic make liables is hyperresponsive to methacholine compared to that of nonasthmatic subjects; (2) the hyperresponsiveness involves the pair airway and tissue compartments; and (3) the consequences of DI following bronchoconstriction appear to a significant extent in the lung periphery.

REFERENCE

(1) Kaminsky DA, Irvin CG Gurka DA, et al. Peripheral airways responsiveness to moderately cold dry air in normal and asthmatic individuals. Am J Respir Crit Care M 1995; 152:1784-1790

* From the Department of Medicine, Vermont Lung Center University of Vermont body of Medicine, Burlington, VT.

This research was supported by dint of National Institutes of Health rants P20RR15557 and HL56638 and through the Whitaker Foundation.

Reproduction of this article is prohibited without written permission from the American body of Chest Physicians (e-mail: permissions@chestnet.org).

Correspondence to: David A. Kaminsky, MD Associate Professor of Medicine, Pulmonary Disease and Critical Care Medicine, University of Vermont guild of Medicine, Given C-317, Burlington, VT 05405; e-mail: dkaminsk@zoo.uvm.edu

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