Therapeutic Advances in Respiratory Disease · Published 2026-07-01 · DOI 10.1177/17534666261467258
Shan Mou, Qi Cai, Wei Xu, Xiaohao Wang, Lei Mao, Lijuan Li, Li Zhang, Yan Zhang
Background: Hypercapnia is linked to a poor prognosis in acute exacerbation of chronic obstructive pulmonary disease (AECOPD) and severe community-acquired pneumonia (SCAP), and reduced early anti-inflammatory capacity in SCAP. However, its impact on AECOPD+SCAP patients remains unclear. Objectives: To assess hypercapnia’s effects on inflammatory responses and short-term outcomes in AECOPD+SCAP patients. Design: This retrospective, dual-center study included 185 hospitalized AECOPD+SCAP patients from January 2014 to June 2025. Methods: Patients were stratified by PaCO 2 levels on the day of admission: hypercapnia (>45 mmHg), normocapnia (35–45 mmHg), and hypocapnia (<35 mmHg). Data were collected on clinical data, biomarkers (procalcitonin [PCT], C-reactive protein [CRP], lactate and red cell distribution width coefficient of variation [RDW-CV]) and 30-day survival. Results: The three groups had similar invasive mechanical ventilation needs and in-hospital and 30-day mortality. Hypercapnic patients (especially with acidosis) had a higher intensive care unit (ICU) admission risk than normocapnic patients. The hypercapnia group had lower PCT, CRP and lactate levels versus the hypocapnia group ( p < 0.05), while RDW-CV showed no significant intergroup differences( p > 0.05). Such trends persisted in ICU-admitted patients, largely independent of acidosis and were unaffected by prior systemic corticosteroid therapy. Multivariate analysis indicated hypercapnia, PaO 2 /FiO 2 , lactate, and RDW-CV could independently predict ICU admission. The nomogram incorporating these predictors showed good discriminatory ability (area under the curve = 0.72), comparable to pneumonia severity scores (CURB-65, PSI, SMART-COP, and Quick SOFA), with clinical utility confirmed by calibration and decision curve analyses. Conclusion: Hypercapnia in AECOPD+SCAP patients could indicate higher ICU admission risk (especially in cases of acidosis) and impaired early anti-inflammatory responses, which are largely independent of acidosis. The combination of hypercapnia, RDW-CV, PaO 2 /FiO 2 ratio, and lactate levels can help to identify patients requiring intensive care.
Abstract from DOAJ. Public domain (CC0 1.0).
Read the article at the publisher →
Mou, S., Cai, Q., Xu, W., et al. (2026). Hypercapnia is associated with an increased risk of ICU admission and reduced inflammatory responses in AECOPD patients with severe pneumonia. Therapeutic Advances in Respiratory Disease. https://doi.org/10.1177/17534666261467258