Rationale Hospitalised patients with acute
exacerbation of COPD may deteriorate despite treatment,
with early readmission being common.
Objectives 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 physiciandefined
episodes of deterioration were recorded daily until
discharge. Readmissions at 14 and 28 days post discharge
were recorded.
Measurements and main 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.