Mechanisms to dyspnoea and dynamic hyperinflation related exercise intolerance in COPD

Abstract

Expiratory flow limitation can develop in parallel with the progression of COPD, and as a consequence, dynamic hyperinflation and lung mechanical abnormalities can develop. Dynamic hyperinflation can cause increased breathlessness and reduction in exercise tolerance. Achievement of critical inspiratory reserve volume is one of the main factors in exercise intolerance. Obesity has specific lung mechanical effects. There is also a difference concerning gender and dyspnoea. Increased nerve activity is characteristic in hyperinflation. Bronchodilator therapy, lung volume reduction surgery, endurance training at submaximal intensity, and heliox or oxygen breathing can decrease the degree of dynamic hyperinflation.Keywords: COPD, dyspnoea, expiratory flow limitation, dynamic hyperinflation, lung mechanics, exercise toleranceOne of the main symptoms in chronic obstructive pulmonary disease (COPD) is dyspnoea, and initially it is manifested during exercise and later at rest with the progression of the disease. Dyspnoea leads to exercise intolerance in parallel with physical inactivity, and as a consequence, disability may develop (28). The main causes of exercise intolerance may be lung mechanical abnormalities and patient's deconditioning (28). Dyspnoea is characterised by an increase in the following factors: respiratory work/ effort ratio, breathing load, end-expiratory lung volume (EELV) related dynamic hyperinflation, intrinsic positive end-expiratory pressure (PEEP) related elastic effort, and neurological sensation (Fig. 1) (28). Dyspnoea manifestation is often associated with dynamic hyperinflation (DH) in patients with COPD from moderate to severe obstruction (26,28,29,35,42). The discrepancy between respiratory centre induced respiratory muscle work and muscle load, and capacity related lung volume changes lead to neuromechanical dissociation (Fig. 2). The consequence of this process is the development of dynamic hyperinflation as a cause of chronic and exertional dyspnoea (28).

Incremental shuttle walk test as an indicator of decreased exercise tolerance in patients with chronic obstructive pulmonary disease

“…This may also be associated with the reduced fitness and dynamic hyperinflation in our sample of patients. Reduced fitness in patients with COPD had been confirmed in previous studies Varga, 2015).…”

Metabolic and Inflammatory Profile in Patients with COPD

“…However, it is unclear whether early identi cation and treatment of metabolic syndrome in patients reduce the risk of developing cardiovascular disease and improves long-term clinical outcomes. Weight loss alone affects a number of risk factors that are very common in obesity, such as hypertension, dyslipidemia, and insulin resistance.Various studies have examined the effect of exercise in overweight and obese individuals through blood pressure, lipid pro les and glucose [32,33]. Improvement in glycated hemoglobin (HbA1c) and insulin sensitivity has been described, and the total duration of exercise appears to be more important than the mode of exercise [34].…”

Lung Volumes

“…Bu durumda solunum sırasında ekspirasyon tamamlanmadan bir sonraki inspirasyon başlar, dolayısıyla hava yolu ve alveollerde pozitif basınç meydana gelir, bu basınca intrensek pozitif ekspirasyon sonu basınç (PEEPi) adı verilir. Dinamik hiperinflasyon ve PEEPi elastik solunum işinde artma, solunum kas yorgunluğu ve alveoler hipoventilasyon, venöz dönüş ve kardiyak outputta azalma gibi olumsuz etkilere sahiptir, KOAH'ta gelişen dispne ve egzersiz intoleransının en önemli nedeni de dinamik hiperinflasyondur (12,16,17). Klinik çalış-malarda FEV 1 ile dispne skorları arasında anlamlı korelasyon gözlenmezken pulmoner hiperinflasyonu yansıtan FRC, RV, IC gibi parametreler anlamlı bulunmuştur.…”