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Hypercapnia at admission, regardless of acidosis, may worsen the outcome of hospitalised patients with chronic obstructive pulmonary disease exacerbations

Year: 2026

Type: article

Abstract: In patients with exacerbation of chronic obstructive pulmonary disease (ECOPD), the presence of respiratory acidosis is considered “ a marker of severity ”, identifying the need for ventilation treatment. The evaluation of ECOPD patients with hypercapnia, even without acidosis, may provide information on patients not commonly defined as “ at risk ”. We retrospectively assessed 407 hospitalised patients with ECOPD, divided into three groups at admission: patients with normocapnia ( N = 176), hypercapnia (PaCO 2 > 45 mmHg and pH ≥ 7.35, N = 126), and acidosis (PaCO 2 > 45 mmHg and pH < 7.35, N = 105). Data on general, clinical, laboratory and microbiological characteristics, and on outcomes (mortality up to 3 years), were collected. Patients with hypercapnia and acidosis had similar functional and clinical characteristics to their normocapnic peers, but of greater severity. The mortality rate at 1 year was similar between hypercapnic and acidotic patients (24% and 25%), and higher than that recorded in the normocapnic group (14%). Similar trends were observed in mortality from 6 months to 3 years. The presence of hypercapnia and acidosis was significantly associated with an increased and independent risk of death at 1 year. A threshold value of PaCO 2 ≥ 55 mmHg was associated with 1-year mortality. In a multivariate analysis considering the new threshold and compared to normocapnia, the presence of hypercapnia (PaCO 2 ≥ 55), regardless of acidosis, was independently associated with a higher mortality risk at 1 year. In hospitalised ECOPD patients, hypercapnia itself, even when compensated, is associated with a worse prognosis up to an intermediate-term follow-up. The need to ventilate these patients should be evaluated, regardless of the presence or absence of acidosis.

Source: Internal and Emergency Medicine

DOI: 10.1007/s11739-026-04279-0

Authors: Giulia Sartori, Alberto Fantin, Filippo Sartori, Albert Gabarrús, Ernesto Crisafulli, Antoni Torres