Mechanism of Controlling Residual Volume and Emptying Rate of the Lung in Young and Elderly Healthy Subjects

Abstract

The mechanisms of controlling residual volume and lung emptying in different ages have been examined. Elastic bandage was wrapped around the abdomen, chest and shoulder (chest strapping). The measurements of various lung volumes and airway resistance were performed with and without chest strapping. Reduction in all lung volumes including residual volume (-12%) and light increase in airway resistance were obtained in subjects below 25 years with chest strapping, whereas residual volumes were higher (+ 17%, + 12%) under chest strapping in subjects between 35 and 50 years and > 60 years of age, respectively. The airway resistance was also considerably higher in these two groups, A decrease in residual volume points to the fact that the major controlling mechanism of residual volume lies in the chest wall. Chest strapping removes the outward force on the airways, enhances their closure, and traps more air, which increases residual volume. This means that the limitation of emptying lies in the airways in advanced age ( > 34 years)

Computer simulation of human breath-hold diving: cardiovascular adjustments

“…Lung airspaces can be safely compressed below residual volume, since standard measured RV in healthy individuals is essentially a consequence of an effortdependent biomechanical limitation of chest wall and abdominal muscle contraction and diaphragmatic stretch (Cook et al 1964;Leith and Mead 1967;Islam 1980). Measured RV also depends on the proportion of normally closed airways, which tends to increase with maximal expiration (Pedersen et al 1984).…”

Review of the Aged Respiratory System

“…It is generally accepted that lung elastic recoil is reduced with advanced age (Begin et d., 1975;Berend et al, 1980;Islam, 1980). The functional significance of elastic recoil decline is, however, controversial and will be discussed later in this review.…”

“…An increase in chest wall rigidity and, therefore, a decrease in compliance appears to be a universally accepted age dependent characteristic (Berend et al, 1980;Exton-Smith & Overstall, 1979;Islam, 1980). A postural tendency toward kyphosis together with chest wall rigidity has been postulated to cause old chests to assume the position of inspiration and result in little chest movement (ExtonSmith & Overstall, 1979).…”

“…Why does this occur? Islam (1980) identified two possible mechanisms that could prevent complete emptying of the lungs: (1) airway closure in which residual volume represents trapped gas behind collapsed airways, and (2) residual volume determined by the action of opposing forces, i.e. lung and chest wall recoil.…”

“…This report is highly suggestive of the importance of aging thoracic rigidity as the greater influence for lung volume alterations. Islam (1980) studied the effects of strapping the abdomen, chest, and shoulders of various age groups. Contrasts were observed between old and young subjects.…”