title: Neural respiratory drive predicts clinical deterioration and safe discharge in exacerbations of COPD.
abstract: BACKGROUND
  Hospitalised patients with acute exacerbation of COPD may deteriorate despite treatment, with early readmission being common.
  
  
  OBJECTIVE
  To investigate whether neural respiratory drive, measured using second intercostal space parasternal muscle electromyography (EMGpara), would identify worsening dyspnoea and physician-defined inpatient clinical deterioration, and predict early readmission.
  
  
  METHODS
  Patients admitted to a single-site university hospital with exacerbation of COPD were enrolled. Spirometry, inspiratory capacity (IC), EMGpara, routine physiological parameters, modified early warning score (MEWS), modified Borg scale for dyspnoea and physician-defined episodes of deterioration were recorded daily until discharge. Readmissions at 14 and 28 days post discharge were recorded.
  
  
  RESULTS
  120 patients were recruited (age 70 ± 9 years, forced expiratory volume in 1 s (FEV1) of 30.5 ± 11.2%). Worsening dyspnoea, defined as at least one-point increase in Borg scale, was associated with increases in EMGpara%max and MEWS, whereas an increase in EMGpara%max alone was associated with physician-defined inpatient clinical deterioration. Admission-to-discharge change (Δ) in the normalised value of EMGpara (ΔEMGpara%max) was inversely correlated with ΔFEV1 (r = -0.38, p < 0.001) and ΔIC (r = -0.44, p < 0.001). ΔEMGpara%max predicted 14-day readmission (OR 1.13, 95% 1.03 to 1.23) in the whole cohort and 28-day readmission in patients under 85 years (OR 1.09, 95% CI 1.01 to 1.18). Age (OR 1.08, 95% CI 1.03 to 1.14) and 12-month admission frequency (OR 1.29, 1.01 to 1.66), also predicted 28-day readmission in the whole cohort.
  
  
  CONCLUSIONS
  Measurement of neural respiratory drive by EMGpara represents a novel physiological biomarker that may be helpful in detecting inpatient clinical deterioration and identifying the risk of early readmission among patients with exacerbations of COPD.
  
  
  BACKGROUND
  NCT01361451.
authors.affiliation: Lane Fox Respiratory Unit, Guy's and St Thomas' NHS Foundation Trust, London, UK Division of Asthma, Allergy and Lung Biology, King's College London, London, UK.
authors.forename: Eui-Sik
authors.initials: ES
authors.lastname: Suh
authors.affiliation: Lane Fox Respiratory Unit, Guy's and St Thomas' NHS Foundation Trust, London, UK Division of Asthma, Allergy and Lung Biology, King's College London, London, UK.
authors.forename: Swapna
authors.initials: S
authors.lastname: Mandal
authors.affiliation: Lane Fox Respiratory Unit, Guy's and St Thomas' NHS Foundation Trust, London, UK.
authors.forename: Rachel
authors.initials: R
authors.lastname: Harding
authors.affiliation: Lane Fox Respiratory Unit, Guy's and St Thomas' NHS Foundation Trust, London, UK Division of Asthma, Allergy and Lung Biology, King's College London, London, UK.
authors.forename: Michelle
authors.initials: M
authors.lastname: Ramsay
authors.affiliation: Lane Fox Respiratory Unit, Guy's and St Thomas' NHS Foundation Trust, London, UK.
authors.forename: Meera
authors.initials: M
authors.lastname: Kamalanathan
authors.affiliation: Emergency Department, Guy's and St Thomas' NHS Foundation Trust, London, UK.
authors.forename: Katherine
authors.initials: K
authors.lastname: Henderson
authors.affiliation: Department of Acute Medicine, Guy's and St Thomas' NHS Foundation Trust, London, UK.
authors.forename: Kevin
authors.initials: K
authors.lastname: O'Kane
authors.affiliation: Division of Health and Social Care Research, King's College London, London, UK.
authors.forename: Abdel
authors.initials: A
authors.lastname: Douiri
authors.affiliation: NIHR Respiratory Biomedical Research Unit at the Royal Brompton & Harefield NHS Foundation Trust and Imperial College, London, UK.
authors.forename: Nicholas S
authors.initials: NS
authors.lastname: Hopkinson
authors.affiliation: NIHR Respiratory Biomedical Research Unit at the Royal Brompton & Harefield NHS Foundation Trust and Imperial College, London, UK.
authors.forename: Michael I
authors.initials: MI
authors.lastname: Polkey
authors.affiliation: Division of Asthma, Allergy and Lung Biology, King's College London, London, UK.
authors.forename: Gerrard
authors.initials: G
authors.lastname: Rafferty
authors.affiliation: Lane Fox Respiratory Unit, Guy's and St Thomas' NHS Foundation Trust, London, UK Division of Asthma, Allergy and Lung Biology, King's College London, London, UK.
authors.forename: Patrick B
authors.initials: PB
authors.lastname: Murphy
authors.affiliation: Division of Asthma, Allergy and Lung Biology, King's College London, London, UK.
authors.forename: John
authors.initials: J
authors.lastname: Moxham
authors.affiliation: Lane Fox Respiratory Unit, Guy's and St Thomas' NHS Foundation Trust, London, UK Division of Asthma, Allergy and Lung Biology, King's College London, London, UK.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Hart
mesh_terms: D000368:Aged; D018450:Disease Progression; D004576:Electromyography; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology*; D012372:ROC Curve; D013147:Spirometry
keywords: COPD Exacerbations; Lung Physiology; Respiratory Muscles