Neural respiratory drive measurement for COPD assessment and monitoring.

Currently there is an unmet need for more objective assessments that could determine COPD severity. Ideally such objective assessments could also anticipate COPD exacerbations in order to decrease the need for repeated hospital admissions. In this review we outline how patients' neural respiratory drive (NRD) may be determined using the electromyography of the diaphragm as an objective measurement of COPD severity. Respiratory muscle NRD is indeed less influenced by patients' voluntary effort limitation than for example when testing for exercise tolerance in which case the patients themselves decide when to stop. Exercise tolerance tests are better correlated with muscle weakness rather than COPD severity per se. NRD would also be less dependent upon patients' subjective perception of the severity of their breathlessness. A key further advantage is that recent studies showed that the diaphragm electromyography measurements using electrodes placed on the skin are correlated with those obtained using specific electrodes, therefore this method is non-invasive and more acceptable for routine clinical practice. Thus, NRD measurements could be used in COPD in a similar way as electrocardiography is used to evaluate and monitor ischemic heart disease. NRD measurements could therefore complement more established instruments such as lung function tests, FEV1, exercise tolerance tests, the BODE index etc. in COPD. This could lead to better COPD management and reduce the acute exacerbations which are amongst the most common causes of repeated hospital admissions and consume significant resources.