Normocapnic versus hypercapnic COPD: relation between biomarkers and ventilatory control

Normocapnic versus hypercapnic COPD: relation between biomarkers and ventilatory control Introduction: Chronic hypercapnia in advanced COPD may contribute to systemic inflammation and impaired ventilatory control; distinguishing normocapnic from hypercapnic patients could help identify risk phenotypes and therapeutic targets. Aims: To compare inflammatory markers (IL-6, TNF-α, CRP) and central CO₂ sensitivity (P0.1/PaCO₂ slope) in normocapnic versus hypercapnic COPD patients. Methods: Patients with moderate-to-severe COPD were included, classified as normocapnic (PaCO₂ ≤45 mmHg) or hypercapnic (PaCO₂ >45 mmHg). Anthropometric and spirometric data were collected. Inflammatory markers (IL-6, IL-8, TNF-α, CRP) and P0.1/PaCO2 slope were measured. Results: Nineteen patients were enrolled (9 normocapnic and 10 hypercapnic). No significant differences were observed in age (68 ± 7 vs 71 ± 8 years, p = 0.18), weight or BMI (p > 0.40). PaCO₂ was higher in hypercapnic patients (52 ± 3 vs 39 ± 3 mmHg, p