A Retrospective Observational Study of Pulmonary Impairments in Long COVID Patients

Background: Pulmonary impairments have been identified as some of the most complex and debilitating post-acute sequelae of SARS-CoV-2 infection (PASC) or long COVID. This study identified and characterised the specific forms of pulmonary impairments detected using pulmonary function tests (PFT), chest X-rays (CXR), and CT scans in patients with long COVID symptoms. Methods: We conducted a single-centre retrospective study to evaluate 60 patients with long COVID who underwent pulmonary function tests (PFTs), chest X-rays (CXRs), and computed tomography (CT) scans. Pulmonary function in long COVID patients was assessed using defined thresholds for key test parameters, enabling categorisation into normal, restrictive, obstructive, and mixed lung-function patterns. We applied exact binomial (Clopper–Pearson) 95% confidence intervals to calculate the proportions of patients falling below the defined thresholds. We also assessed the relationship among spirometric indices, lung volumes, and diffusion capacity (DLCO) using scatter plots with corresponding linear regression. The findings from the CXRs and CT scans were categorised, and their prevalence was calculated. Results: A total of 60 patients with long COVID symptoms (mean age 60 ± 13 years; 57% female) were evaluated. The cohort was ethnically diverse and predominantly non-smokers, with a mean BMI of 32.4 ± 6.3 kg/m². Pulmonary function testing revealed that most patients had preserved spirometry, with mean FEV1 and FVC above 90% predicted. However, a significant proportion exhibited reductions in lung volumes, with total lung capacity (TLC) decreasing in 35%, and diffusion capacity (TLCO) decreasing in 75%. Lung function pattern analysis showed 88% of patients had normal function, while 12% displayed a restrictive pattern; no obstructive or mixed patterns were observed. Radiographic assessment revealed that 58% of chest X-rays were normal, whereas CT scans showed ground-glass opacities in 65% and fibrotic changes in 55% of patients, along with findings such as atelectasis, air trapping, and bronchial wall thickening. Conclusion This study reveals that long COVID is marked by preserved spirometry yet significant alveolar gas exchange impairment, with frequent diffusion deficits, fibrotic changes, and ground-glass opacities indicating persistent parenchymal and microvascular injury. These findings highlight the need for ongoing research and multidisciplinary management to address the enduring impact of chronic pulmonary dysfunction.