Estimated Plasma Volume Status and the Risk of in-Hospital Mortality Among Patients with Acute Exacerbations of Chronic Obstructive Pulmonary Disease in Intensive Care Unit: Retrospective Cohort Study from the eICU Collaborative Research Database.

Purpose: Globally, acute exacerbations of chronic obstructive pulmonary disease (AECOPD) are the leading cause of hospitalization and mortality in COPD patients. The estimated plasma volume status (ePVS) is an indicator of fluid status that has been proven to correlate with the prognosis of intensive care unit (ICU) patients. Our study aims to explore the association of ePVS and in-hospital mortality in AECPD patients admitted in the ICU.

Methods: Data of this retrospective cohort study were extracted from the electronic Intensive Care Unit Collaborative Research Database (eICU-CRD). Outcome was the in-hospital mortality in AECOPD patients. The formulas, Duarte formula and Kaplan-Hakim (KH) formula, were used to assess ePVS. The weighted univariable and multivariable Cox regression models were utilized to explore the association of Duarte-ePVS and KH-ePVS and in-hospital mortality in AECOPD patients, with hazard ratios (HRs) and 95% confidence intervals (CIs). Kaplan-Meier survival analysis was used to pool the in-hospital mortality for different KH-ePVS levels. Restricted cubic splines curve analysis was used to assess the linear correlation of KH-ePVS and in-hospital mortality in AECOPD patients. These associations were further explored in different subgroups.

Results: In total, 2,773 AECOPD patients were included, of whom, 219 (7.90%) died within 6.24 (4.01-9.26) days. After adjusted confounding factors, we found AECOPD patients with high KH-ePVS level were associated with high risk of in-hospital mortality (HR=1.53, 95% CI: 1.05-2.24). No significant association was found between Duarte-ePVS and in-hospital mortality (P>0.05). The Kaplan-Meier analysis also suggested consistent association between KH-ePVS and in-hospital mortality in AECOPD patients. Subgroup analysis also suggested the association of KH-ePVS and in-hospital mortality in AECOPD patients remained robust.

Conclusion: Elevated KH-ePVS levels are associated with the high in-hospital mortality among AECOPD patients. As a simple and convenient indicator, KH-ePVS is expected to become a prognostic predictor for predicting in-hospital mortality in severe AECOPD patients.