Neural respiratory drive (NRD) to predict long term mortality after an acute exacerbation of COPD (AECOPD)

Abstract

Introduction: NRD can predict safe discharge following an AECOPD. Our aim was to assess if NRD could predict long term mortality. Methods: Post-hoc analysis of a prospective cohort. NRD was assessed by parasternal EMG and was measured at hospital admission and at discharge. EMGpara%max was defined as the ratio between EMGpara during tidal breathing and during sniff manoeuvre. Results: Of 120 patients, 69 (57.5%) died. Mean follow up was 3.3±1.8years. The cause of death was attributable to respiratory disease in the majority of cases (n=29, 40%). At discharge, an EMGpara%max >14.84% was associated with a significantly worse prognosis with a median survival of: 998 days vs. 2002 days when it was below (HR 1.89 [95%CI 1.20 – 3.10], p=0.009, log-rank) (Figure 1). In multivariate analysis, factors associated with a poor prognosis were: EMGpara%max at discharge >14.84% (HR 2.15 [95%CI 1.30 – 5.55], p:0,003), age >71 years (HR 2.04 [95%CI: 1.24 – 3.35], p:0.005), a PaCO2 at admission >5.56 kPa (HR 1.81 [95%CI: 1.08 – 3.03], p:0.015) and previous long term oxygen use (HR 3.34 [95%CI 1.69 – 6.61], p:0.001). Conclusion: Our post-hoc analysis suggests that discharge NRD is an independent predictor of long term mortality in patients following admission for an AECOPD. Future work should investigate the benefit of targeting modifiable factors such as NRD and PaCO2 following AECOPD. 1-Suh E-S. Thorax 2015;70:1123–30