Effects of pulmonary congestion on airway reactivity to histamine aerosol in dogs

Abstract

We examined the effect of acute pulmonary vascular congestion on bronchial reactivity in dogs in a standard challenge protocol. Airway responsiveness to histamine whose concentration was varied in a stepwise incremental fashion was assessed from changes in pulmonary resistance (RL) and dynamic compliance (Cdyn) in 10 anesthetized dogs. Brief acute pulmonary congestion was created by inflating a balloon placed in the left atrium to raise left atrial pressure to 20-30 cmH2O for 1 min. Pulmonary congestion did not change RL in the control condition. However, after histamine inhalation, RL was further increased by pulmonary congestion, making the two effects synergistic. This phenomenon could not be observed with vagi cut. Pulmonary congestion decreased Cdyn in all dogs regardless of histamine concentration, with or without vagotomy. We conclude that pulmonary vascular congestion makes the bronchi hyperreactive through vagal reflexes. The reduction in Cdyn caused by pulmonary congestion appears to stem mainly from the narrowing of peripheral airways by adjacent vascular engorgement.

Reduction of Bronchial Responsiveness to Methacholine after Mitral Valve Replacement

“…In dogs acute pulmonary vascular congestion renders the bronchi hyperresponsive to histamine through vagal reflexes [3]. Congestion and edema of bronchial wall have been suggested as possible mechanisms of bronchial hyperresponsiveness by Cabanes et al [2] on the basis of the protective effect of methoxamine on methacholine-induced bronchoconstriction in patients with im paired left ventricular function.…”

Precapillary pulmonary hypertension leads to reversible bronchial hyperreactivity in rats

“…In the presence of such POSTPHT, numerous clinical studies have demonstrated a compromised lung function and the development of BHR both in patients with an impaired left ventricular function [1,[7][8][9] or valvular diseases [10]. Experimental models have been utilized successfully in various animal species in order to characterize the pulmonary consequences of acute POSTPHT [2,[11][12][13] and have contributed considerably to a better understanding of this disorder.…”

Prolonged hypoxemia after 10min walking exercise in aged patients with chronic obstructive pulmonary disease.

“…Pulmonary artery wedge pressure during mild exercise increases markedly in patients with COPD even though they have no overt left heart disease and no increase in the esophageal pressure as a reflection of mean intrathoracic pressure (Butler et al 1988). Vascular congestion is reported as one of the factors that causes bronchoconstriction and ventilation-perfusion unevenness (Kikuchi et al 1984). Physical signs are those of chronic obstructive airflow disease with widespread airway adventitial sounds such as rhonchi or wheeze, the severity of the latter depending upon whether the precipitating deterioration is predominantly asthmatic or not.…”