PT  - JOURNAL ARTICLE
AU  - C. J. Jolley
AU  - Y-M. Luo
AU  - J. Steier
AU  - C. Reilly
AU  - J. Seymour
AU  - A. Lunt
AU  - K. Ward
AU  - G. F. Rafferty
AU  - M. I. Polkey
AU  - J. Moxham
TI  - Neural respiratory drive in healthy subjects and in COPD
AID  - 10.1183/09031936.00093408
DP  - 2009 Feb 01
TA  - European Respiratory Journal
PG  - 289--297
VI  - 33
IP  - 2
4099  - http://erj.ersjournals.com/content/33/2/289.short
4100  - http://erj.ersjournals.com/content/33/2/289.full
SO  - Eur Respir J2009 Feb 01; 33
AB  - The aim of the present study was to use the diaphragm electromyogram (EMGdi) to compare levels of neural respiratory drive (NRD) in a cohort of healthy subjects and chronic obstructive pulmonary disease (COPD) patients, and to investigate the relationship between NRD and pulmonary function in COPD. EMGdi was recorded at rest and normalised to peak EMGdi recorded during maximum inspiratory manoeuvres (EMGdi % max) in 100 healthy subjects and 30 patients with COPD, using a multipair oesophageal electrode. EMGdi was normalised to the amplitude of the diaphragm compound muscle action potential (CMAPdi,MS) in 64 healthy subjects. The mean±sd EMGdi % max was 9.0±3.4% in healthy subjects and 27.9±9.9% in COPD patients, and correlated with percentage predicted forced expiratory volume in one second, vital capacity and inspiratory capacity in patients. EMGdi % max was higher in healthy subjects aged 51–80 yrs than in those aged 18–50 yrs (11.4±3.4 versus 8.2±2.9%, respectively). Observations in the healthy group were similar when peak EMGdi or CMAPdi,MS were used to normalise EMGdi. Levels of neural respiratory drive were higher in chronic obstructive pulmonary disease patients than healthy subjects, and related to disease severity. Diaphragm compound muscle action potential could be used to normalise diaphragm electromyogram if volitional inspiratory manoeuvres could not be performed, allowing translation of the technique to critically ill and ventilated patients.