3 Dyspnea
Similar to pain, often referred to as the fifth vital sign, in this guideline we suggest that dyspnea be considered as the sixth
vital sign for individuals with COPD. Dyspnea is a complex phenomenon that is most commonly understood as the
subjective experience of breathlessness [23-26]. Dyspnea is the most disabling symptom of COPD. From a physiological
perspective dyspnea is associated with elements involving sensory perception, central processing and motor commands;
factors associated with respiratory effort, chemoreceptors or chemical factors that affect the respiratory drive and
mechanoreceptors or sites of dyspnogenesis [27, 28]. Moreover, O’Donnell et al. [29] suggest that peripheral airway
obstruction traps air during expiration resulting in hyperinflation which in turn reduces inspiratory capacity and is possibly
the main mechanism of exertional dyspnea.