Determining the cause of dyspnoea: linguistic and biological descriptors.

Dyspnoea is the most common symptom of patients with cardio-respiratory diseases. It is a generic term related to different pathophysiological abnormalities that may result in different qualities of respiratory discomfort, defined by specific verbal descriptors for a specific diagnosis. Often it is difficult to distinguish the underlying pathology of dyspnoea, eg, either from chronic heart failure (CHF) or from other respiratory causes. The discovery of the endocrine function of the heart, as well as the development of accurate and feasible assay methods allow the use of cardiac natriuretic hormones in the assessment of cardiovascular diseases, namely acute coronary syndromes and heart failure. It is advisable to measure cardiac natriuretic hormones in order to exclude or suggest the diagnosis of CHF in patients with a suspicious diagnosis, but with ambiguous signs and symptoms or manifestations that can be confused with other pathologies (like chronic obstructive pulmonary disease). The most common symptom of patients with cardio-respiratory diseases is dyspnoea, a 'difficult, laboured, uncomfortable breathing'. Dyspnoea has been defined as 'a term used to characterize a subjective experience of breathing discomfort that consists of qualitatively distinct sensations that vary in intensity. The experience derives from interactions among multiple physiological, psychological, social and environmental factors, and may induce secondary physiological and behavioural responses'. Breathlessness is characterized by measurable intensity and qualitative dimensions, which may vary depending on the individual, the underlying disease, and other circumstances.3 The neurophysiological basis of dyspnoea relies on receptors in the airways lung parenchyma, respiratory muscles together with chemoreceptors providing sensory feedback via vagal, phrenic and intercostal nerves to the spinal cord, medulla and higher centres. Breathlessness is based on different pathophysiolagical abnormalities that may result in different qualities of respiratory discomfort, which are defined by specific verbal descriptors related to a specific diagnosis. Nevertheless different diseases may share the same descriptors. There is no clear relationship between the qualitative descriptors of dyspnoea and the quantitative intensity among the patient groups: different diseases may be distinguished by quality but not intensity of the sensation. Differences in languages, in races, cultures, gender, and in the manner in which concepts or symptoms are held can all influence the idea, quality and intensity of dyspnoea.