PATIENTS recovering from severe COVID-19 pneumonia may experience persistent lung function impairment long after hospital discharge, with new research highlighting vascular dysfunction as a key driver of long-term damage. A recent study assessed post-ICU patients with ongoing lung diffusion impairments, shedding light on the underlying mechanisms behind these complications.
The study followed patients with reduced Lung Diffusing Capacity for Carbon Monoxide (DLCO) for up to two years after severe SARS-CoV-2 infection. Researchers conducted spirometry, DLCO tests, and six-minute walking tests every six months. If diffusion impairments persisted beyond 18-24 months, a combined Lung Diffusing Capacity for Nitric Oxide (DLNO) and DLCO assessment was performed to differentiate between alveolar membrane dysfunction (DmCO) and pulmonary capillary blood volume (Vc) impairment.
Among the 20 patients with prolonged DLCO reduction, 16 exhibited significant reductions in pulmonary capillary blood volume (Vc), while alveolar membrane function (DmCO) was less frequently impaired. The study found that the DLNO/DLCO ratio exceeded 113.5% in all participants, indicating that long-term gas exchange issues were primarily due to vascular dysfunction rather than damage to the alveolar membrane.
These findings suggest that the lingering respiratory symptoms seen in post-COVID patients stem largely from prolonged pulmonary capillary circulation impairment. This distinction is critical for treatment strategies, as it underscores the vascular component of long-term lung damage rather than a purely alveolar issue.
As clinicians continue to manage the long-term effects of COVID-19, these insights may help guide more targeted therapeutic approaches for patients suffering from persistent breathing difficulties.
Reference: Pini L et al. Long-term alveolar-capillary diffusion impairments after severe SARS-CoV-2 pneumonia. Ann Med. 2025 Dec;57(1):2483383.
Anaya Malik | AMJ
