The Relationship of Pulmonary Compliance to Pulmonary Vascular Pressures in Patients With Heart Disease 1

Abstract

The mechanisms of dyspnea in congestive heart failure, although intensively investigated, have yet to be completely elucidated. Cardiac dyspnea has long been attributed to structural or functional changes in the lungs secondary to cardiac failure. Morphological alterations were first described by the pathologists of the 19th century. More recently, in the 20th century, this morphological approach has been complemented by determinations of pulmonary function during life.Prominent among the early observations of functional impairment were Peabody and Wentworth's correlation of cardiac dyspnea with decreased vital capacity (1), followed by Christie and Meakins' measurement of increased excursions of intrapleural pressure in heart failure (2), and the demonstration in experimental animals that pulmonary vascular congestion reduces pulmonary distensibility (3, 4). In vivo estimations of pulmonary blood volume in heart disease, however, have failed to demonstrate the expected correlations between increasing pulmonary vascular volume, increasing pulmonary vascular pressures and dyspnea (5-7). The limitations of existing methods may be responsible. Recently, emphasis has been placed upon the quantitative evaluation of the elastic properties of the lung in relation to cardiac dyspnea (8, 9). These studies have shown

Effects of pulmonary vascular pressures and flow on airway and parenchymal mechanics in isolated rat lungs

“…Some investigations have revealed a clear correlation between an elevated Ppa and the subsequent changes in the mechanical properties of the lungs (2,13,23,27,28), although the increases in Ppa were always associated with increases in pulmonary venous pressures in those investigations. Other studies failed to detect any change in lung function in the presence of an elevated Ppa (3,6,7,11,22,26). The findings of the present study are in accord with the latter observations, demonstrating only poor quantitative relationships between Ppa and the lung mechanical parameters.…”

Pulmonary and Circulatory Effects of Acute Pulmonary Vascular Engorgement in Normal Subjects 1

“…There was a good correlation between decrease in compliance and reduction in vital capacity. Examinations have been made of the effect on compliance of elevating pulmonary vascular pressures by exercise in patients with mitral stenosis (8,11). This often causes a decrease in compliance, but it may fail to do so in cases where compliance is already much reduced at rest.…”

The Effect of Body Position Change on Lung Compliance in Normal Subjects and in Patients With Congestive Heart Failure*

“…Saxton, Rabinowitz, Dexter and Haynes (6) found reversible decreases in compliance to onehalf the resting value in cardiacs on exercise. These large decreases in lung compliance were in some cases associated with pulmonary capillary pressure rises as small as 6 to 10 mm.…”

“…More recent studies of pulmonary mechanics in patients with congestive heart failure (2-5) have emphasized the lowered lung compliance as well as moderate increases in pulmonary resistance. That acute changes in lung compliance can occur in man has been shown by Saxton, Rabinowitz, Dexter and Haynes (6) who demonstrated acute decreases in lung compliance on exercise in patients with heart disease associated with increases in pulmonary artery wedge pressure, and by Bondurant, Hickam and Isley (7) who demonstrated acutely decreased compliance in normal subjects when transient pulmonary congestion was induced by sudden inflation of a pressurized suit. Because of the importance of body position in cardiac dyspnea, a feature of which is orthopnea, the present study was undertaken to determine what, if any, changes in the static volume-pressure characteristics of the lungs occurred in normal subjects and in orthopneic patients with heart failure on changing from the sitting to the horizontal (prone) body position.…”