Quasntification Of Dyspnea With Neural Respiratory Drive

Objective: Severity of dyspnea usually mainly relies on subject’s feeling. No objectivemethod is currently available to quantify dyspnea. The aim of the study was to investigatewhether diaphragm EMG recorded from esophageal electrode to quantify dyspnea.Methods: Ten healthy young subjects, thirteen healthy middle-old subjects, and fourteenstable patients with chronic obstructive pulmonary disease (COPD) were studied.Conventional lung function tests were performed in all the subjects. Dyspnea was inducedby cardiopulmonary exercise test (CPET) in laboratory. Diaphragm EMG was recordedfrom a multipair esophageal electrode during incremental treadmill exercise. ConventionalBorg scale of dypnea and modified dyspnea scores [none (0), mild (1), moderate (2),severe (3), and very severe (4)] were assessed during exercise. A correlation betweenamplitude of root mean square of EMGdi and dyspnea score was analyzed..Results: There was a good linear relation between RMS of the diaphragm EMG anddyspnea score in all subjects and the relation coefficient (r) was0.977±0.026,0.973±0.025,and0.958±0.051(all P <0.05), in healthy young subjects, healthy middle-old subjects andpatients with COPD, respectively. The correlation between modified dyspnea scores andEMGdi was significantly better than the Borg scale for both health young subjects andmiddle-old subjects but the relation was similar for patients with COPD. EMGdi duringmild dyspnea was (22.2±9.0)%,(41.0±7.7)%, and (44.0±17.0)%, in the healthy youngsubjects, the healthy middle-old subjects and patients with COPD, respectively. There wasa significantly difference between diaphragm EMG at different modified dyspnea scores(all P <0.05) although there were overlaps in diaphragm EMG between different modifieddyspnea.Conclusions: Diaphragm EMG recorded from multipair esophageal eelctrode is useful toquantify the severity of dyspnea in both nrmal subjects and patients with COPD...