Loss of functional residual capacity in poliomyelitis

Abstract

Vital capacity, expiratory reserve volume, and functional residual capacity were determined on 11 normal controls and 25 postpoliomyelitis patients with a chronic flaccid respiratory paralysis. In general, the expiratory reserve volume diminished concomitantly with the vital capacity. As the residual volume was the same in the two groups the lost expiratory reserve volume of the patients had not been added to it. The expiratory reserve volume and functional residual capacity were significantly smaller in the patient group than in the controls. Relaxation pressure-volume curves determined for ten patients and eight controls indicated a loss of compliance of the thoracopulmonic unit of the patients somewhat greater than would be expected from the smaller functional residual capacity, implying some loss of elasticity in the lungs and/or chest wall in the disease process. Submitted on November 17, 1960

Analysis of lung volume restriction in patients with respiratory muscle weakness.

“…This is strong evidence that the fall in FRC in these patients is caused primarily by a decrease in the (outward) pull of the chest wall. This observation is consistent with other studies that demonstrated that the ability of the chest wall to recoil outwards decreased in normal volunteers when acute weakness of the respiratory muscles was produced by partial curarisation.12 Moreover, in our patients, a close relationship existed between the inspiratory muscle force and the decrease of both FRC and Pst (1) at FRC (fig 2), fu-rther suggesting that the reduction of the chest wall force is 'a, Analysis of lung volume restriction in patients with respiratory muscle weakness related to the degree of involvement of the inspiratory muscles. Such a decrease in the outward pull of the chest wall would contribute to the disproportionate loss of lung volume observed in our patients.…”

“…Figure 8 illustrates the theoretical relationship between FRC and transpulmonary pressure at FRC when the PV characteristic of the chest wall remains unchanged (solid curve): when an increase in lung recoil pressure is the only cause of a decreased FRC, the Pst (1) at FRC must increase. By contrast, in most of our patients, the decrease in FRC was assoiciated with a decrease, not an increase, in Pst (1) at FRC (fig 8). This is strong evidence that the fall in FRC in these patients is caused primarily by a decrease in the (outward) pull of the chest wall.…”

“…Several deflational PV curves were obtained in each patient and a line of best fit was drawn by eye through at least three sets of PV data that agreed to ± 1 cm HAO. The static recoil pressure of the lung (Pst (1) ) was measured at various percentages of total lung capacity (TLC) that was calculated by adding to FRC the mean inspiratory capacity measured during the X-Y recording of the PV curves. Static expiratory lung compliance was measured as the slope of the PV curve over the 0-5 litre above functional residual capacity (FRC).…”

“…' We recently investigated pulmonary mechanics in 25 patients with a variety of generalised neuromuscular disorders and a wide range of respiratory muscle performance. The three main purposes of the present report are: (1) to delineate the pattern of pulmonary function associated with respiratory muscle weakness; (2) to evaluate the lung volume restriction associated with a chronic involvement of the respiratory muscles, with particular emphasis on the relationship between loss of respiratory muscle strength and loss of lung volume; and (3) Statilc expiratory 'lung icompliance was markedly decreased in our patients. Most clearly, this reduction far exceeded the effects that could result from the only difference in lung volume history, and values o-f compliance obtained during inflation were also reduced.…”

Effect of pattern and severity of respiratory muscle weakness on carbon monoxide gas transfer and lung volumes

“…It is well established that weakness of the respiratory muscles causes a restrictive ventilatory defect with a reduction in TLC. However, the resting end expiratory position (FRC) in patients with respiratory muscle weakness can be decreased [19,[25][26][27], normal [28,29] or increased [30], while RV can be normal [19,27] or increased [22,[28][29][30]. To examine whether these differences could be due to differences in the distribution of respiratory muscle weakness, the current authors analysed values of FRC and RV in eight studies [2,19,22,[30][31][32][33][34] that have reported both lung volumes and inspiratory and/or expiratory muscle function.…”