Factors Limiting Exercise Tolerance in Chronic Lung Diseases

Abstract

The major limitation to exercise performance in patients with chronic lung diseases is an issue of great importance since identifying the factors that prevent these patients from carrying out activities of daily living provides an important perspective for the choice of the appropriate therapeutic strategy. The factors that limit exercise capacity may be different in patients with different disease entities (i.e., chronic obstructive, restrictive or pulmonary vascular lung disease) or disease severity and ultimately depend on the degree of malfunction or miss coordination between the different physiological systems (i.e., respiratory, cardiovascular and peripheral muscles). This review focuses on patients with chronic obstructive pulmonary disease (COPD), interstitial lung disease (ILD) and pulmonary vascular disease (PVD). ILD and PVD are included because there is sufficient experimental evidence for the factors that limit exercise capacity and because these disorders are representative of restrictive and pulmonary vascular disorders, respectively. A great deal of emphasis is given, however, to causes of exercise intolerance in COPD mainly because of the plethora of research findings that have been published in this area and also because exercise intolerance in COPD has been used as a model for understanding the interactions of different pathophysiologic mechanisms in exercise limitation. As exercise intolerance in COPD is recognized as being multifactorial, the impacts of the following factors on patients' exercise capacity are explored from an integrative physiological perspective: (i) imbalance between the ventilatory capacity and requirement; (ii) imbalance between energy demands and supplies to working respiratory and peripheral muscles; and (iii) peripheral muscle intrinsic dysfunction/weakness.

Exertional dyspnoea in interstitial lung diseases: the clinical utility of cardiopulmonary exercise testing

“…Exertional dyspnoea and consequent reduced exercise tolerance have been reported to be multifactorial [23,24]. Here, the main pathophysiological mechanisms are described in detail.…”

Pulmonary vascular and cardiac impairment in interstitial lung disease

“…The correlation between rise in mPAP and fall in systemic oxygenation in exercising IPF patients suggests that this may be in part due to amplified hypoxic vasoconstriction during exercise [51]. Additionally, parenchymal lung abnormalities may impair the mechanisms of pulmonary vascular recruitment and distension that normally prevent disproportionate surges in PAP during exercise [52]. Eventually, increased filling pressure in the pulmonary vasculature, right heart and central veins is thought to affect the breathing pattern and exaggerate dyspnoea [53].…”

“…As a result of the relatively reduced stroke volume, patients with ILD typically have heart rate values higher than normal (compensating tachycardia) [52] that allow for a preserved cardiac output at submaximal levels of exercise [57]. Tachycardia may also be independently triggered by arterial hypoxaemia.…”

Early surgery increases mitochondrial DNA release and lung injury in a model of elderly hip fracture and chronic obstructive pulmonary disease

“…Chronic lung disease is a compelling reason for delaying surgery and patients often require additional treatments and tests that are time-consuming. Chronic obstructive pulmonary disease (COPD), including chronic bronchitis and emphysema, is a type of obstructive lung disease characterized by chronically poor airflow (10). It is typically progressive in nature and not fully reversible.…”