Abstract
Dyspnoea is a common symptom that afflicts persons with myriad medical conditions. Among sufferers of lung disorders such as chronic obstructive pulmonary disease, dyspnoea, together with effort intolerance, are the major complaints. Dyspnoea is a marker of disease severity and adverse prognosis of chronic obstructive pulmonary disease, and the need for symptom alleviation in improving health status is ever-present, but the quantification of this symptom is challenging in clinical practice, and is mostly limited to the use of questionnaires and self-reports currently. Numerous psychometric tools have been developed to measure the severity of dyspnoea clinically, but their utility is vitiated by the complexity and multidimensional nature of the symptom. The lack of a universally accepted and accurate measurement tool is likely to hinder future progress in developing novel treatments for relieving dyspnoea.
Physiological measurements have been used to complement or supplant psychometric evaluation of dyspnoea but simple stationary lung function tests do not correlate sufficiently well with dyspnoea severity in patients with chronic obstructive pulmonary disease, while complex exercise testing is impractical or limited to specialized research labs. In recent years, the use of non-invasive surface electromyography of the diaphragm and/or accessory muscles of respiration is gaining attention as a promising physiological assessment of dyspnoea with potential for widespread clinical applications. Although substantial technological gaps still exist between bench and bedside, the current interest, as evidenced by the number of med-tech collaborations in surface respiratory electromyography, appears to be well justified. This review aims to summarize the past and present methodologies as well as future developments in evaluating and quantifying dyspnoea, especially in patients with chronic obstructive pulmonary disease.