Monitoring Long-Term Respiratory Sequelae in Post-COVID-19 Patients: A Primary Care Perspective

A retrospective cohort study of 97 adults with post-COVID-19 syndrome found persistent reductions in gas transfer and a restrictive ventilatory pattern lasting up to 22 months—evidence of measurable long-term pulmonary impairment that can limit daily function.

DLCO reduction was the dominant persistent abnormality, with restrictive changes reflected in lower total lung capacity (TLC) and forced vital capacity (FVC). While volumes and flows improved most in the first months, diffusion deficits persisted long-term; KCO and alveolar volume showed variable effects, indicating mixed alveolar–capillary and volumetric contributions. These objective deficits correlated with ongoing dyspnea and reduced functional capacity in many patients.

Greater acute illness severity predicted larger and longer-lasting decreases in FVC, DLCO and KCO, suggesting a dose–response relationship between initial pulmonary injury and chronic impairment. Most patients recovered volumes and flows within 6–12 months, with further gradual gains up to about 18 months; diffusion impairment often lagged and remained subnormal beyond 12–18 months in a subset. Overall, initial disease severity and baseline pulmonary reserve were the main determinants of prolonged deficits.

In primary care, a focused respiratory symptom review combined with resting and exertional pulse oximetry at the first post-acute visit is an efficient initial screen. For symptomatic patients or those hospitalized during acute illness, targeted spirometry including DLCO at 3–6 months is reasonable, with repeat testing around 12 months if abnormalities persist. Escalate to imaging or pulmonology for progressive declines in DLCO or FVC between visits, clinically relevant resting or exertional desaturation (for example, SpO2 ≲90% with exertion), or persistent functional limitation that interferes with work or daily activities. Organize follow-up as a structured, time-limited monitoring cadence that remains responsive to progressive findings.