Background and Objectives: Severe and critical COVID-19 pneumonia can lead to long-term complications, especially affecting pulmonary function and immune health. However, the extent and progression of these complications over time are not well understood. This study aimed to assess lung function, radiological changes, and some immune parameters in survivors of severe and critical COVID-19 up to 12 months after hospital discharge. Materials and Methods: This prospective observational cohort study followed 85 adult patients who were hospitalized with severe or critical COVID-19 pneumonia at a tertiary care hospital in Vilnius, Lithuania, for 12 months post-discharge. Pulmonary function tests (PFTs), including forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), and diffusion capacity for carbon monoxide (DLCO), were conducted at 3, 6, and 12 months. High-resolution chest computed tomography (CT) scans assessed residual inflammatory and profibrotic/fibrotic abnormalities. Lymphocyte subpopulations were evaluated via flow cytometry during follow-up visits to monitor immune status. Results: The median age of the cohort was 59 years (IQR: 51-64). Fifty-three (62.4%) patients had critical COVID-19 disease. Pulmonary function improved significantly over time, with increases in FVC, FEV1, VC, TLC, and DLCO. Residual volume (RV) did not change significantly over time, suggesting that some aspects of lung function, such as air trapping, remained stable and may require attention in follow-up care. The percentage of patients with restrictive spirometry patterns decreased from 24.71% at 3 months to 14.8% at 12 months (p < 0.05). Residual inflammatory changes on CT were present in 77.63% at 6 months, decreasing to 69.62% at 12 months (p < 0.001). Profibrotic changes remained prevalent, affecting 82.89% of patients at 6 months and 73.08% at 12 months. Lymphocyte counts declined significantly from 3 to 12 months (2077 cells/µL vs. 1845 cells/µL, p = 0.034), with notable reductions in CD3+ (p = 0.040), CD8+ (p = 0.007), and activated CD3HLA-DR+ cells (p < 0.001). This study found that higher CD4+ T cell counts were associated with worse lung function, particularly reduced total lung capacity (TLC), while higher CD8+ T cell levels were linked to improved pulmonary outcomes, such as increased forced vital capacity (FVC) and vital capacity (VC). Multivariable regression analyses revealed that increased levels of CD4+/CD28+/CD192+ T cells were associated with worsening lung function, while higher CD8+/CD28+/CD192+ T cell counts were linked to better pulmonary outcomes, indicating that immune dysregulation plays a critical role in long-term respiratory recovery. Conclusions: Survivors of severe and critical COVID-19 pneumonia continue to experience significant long-term impairments in lung function and immune system health. Regular monitoring of pulmonary function, radiological changes, and immune parameters is essential for guiding personalized post-COVID-19 care and improving long-term outcomes. Further research is needed to explore the mechanisms behind these complications and to develop targeted interventions for long COVID-19.

The diagnosis and management of the most prevalent chronic respiratory diseases partially rely on parameters obtained from pulmonary functional tests (PFTs), including spirometry, plethysmography, and carbon monoxide diffusion capacity (DLCO) measurement. In practice, the interpretation of PFTs' parameters is based on international recommendations issued by renowned scientific societies such as the American Thoracic Society (ATS) and the European Respiratory Society (ERS). The interpretation standards for PFTs established by ATS/ERS in 2005 were updated in 2022. According to the ATS/ERS-2022 standards, the interpretation of PFTs can be summarized in five steps. The first step involves comparing the determined parameters with those observed in a reference population of healthy individuals. This step helps determine whether the determined parameters are low, normal, or elevated. The second step aims to identify potential ventilatory impairments, such as obstructive and/or restrictive ventilatory impairments, which can be observed in certain chronic respiratory or extrarespiratory diseases. The third step involves assessing the severity of the identified ventilatory impairment or the decrease in DLCO. The fourth step entails evaluating the response to bronchodilator testing, if performed. Finally, if previous PFTs results are available, it is important to identify significant changes in certain PFTs parameters over time by comparing current and previous results. This clinical practice guide provides a comprehensive synthesis of the different steps in PFTs interpretation, taking into account the recommendations from ATS/ERS-2022.

Short- and medium-term cardio-pulmonary sequelae after COVID-19 have been extensively studied. However, studies with longer follow-ups are required. This study aims to identify and characterise cardio-pulmonary sequelae, in patients hospitalised for SARS-CoV-2 pneumonia, at 24 months follow-up. This is a prospective, observational cohort study conducted on consecutive patients hospitalised for COVID-19 and acute respiratory failure. Patients were followed up at 24 months with complete pulmonary function tests (PFTs), 6-min walking test and a dyspnoea score (Modified Medical Research Council scale). A subgroup of patients with at least one clinical or functional sign suggestive of increased pulmonary pressures also underwent transthoracic echocardiography (TTE) to evaluate the presence of direct or indirect signs of pulmonary hypertension (PH). Ninety consecutive patients (74% men, median age 59.1 years) were enrolled in the study. In regard to PFTs, carbon monoxide diffusion capacity (DLCO) impairment was observed in 23 cases (26%), in all cases of mild entity. When considering the dyspnoea, 30 (34%) patients showed some degree of breathlessness. Forty patients underwent TTE. No patients had overt PH or chronic thromboembolic PH. However, all patients showed a hyperdynamic state of the right ventricle, and 8 (20%) patients had a decreased acceleration time on pulmonary valve, signs of increased pulmonary vasculature resistances and afterload elevation. At 24-month follow-up after severe COVID-19, DLCO and TTE prove to be the most sensitive tool to detect cardio-pulmonary sequelae. Dyspnoea is still present in about one-third of patients and requires a multidisciplinary approach.

Idiopathic pulmonary fibrosis (IPF) is a debilitating condition, with a life expectancy of 2 to 5 years after diagnosis. Pirfenidone is a drug that has been shown to reduce the decline in forced vital capacity (FVC). We sought to identify whether different patterns on high-resolution computed tomography (HRCT) have different clinical effects through a retrospective comparison of baseline values and changes in pulmonary function tests (PFTs) after treatment with pirfenidone. We retrospectively analyzed data from IPF patients treated with pirfenidone at Nanjing Drum Tower Hospital in Jiangsu Province, China. According to the HRCT pattern, the patients were divided into usual interstitial pneumonitis (UIP) and possible UIP groups. Baseline clinical characteristics and changes every 6 months in the PFTs during the follow-up period were compared between the 2 groups. A total of 65 consecutive patients were enrolled. According to the HRCT pattern, patients were clustered into the UIP group (n = 46) and possible UIP group (n = 19). No difference was observed in the baseline PFTs ratio between the 2 groups. The FVC values of the 2 groups were not significantly different at the initial treatment and at 6 and 12 months after pirfenidone treatment (P = .081, 0.099, and 0.236, respectively). The improvement in % diffusion capacity of the lung for carbon monoxide (%DLCO) was higher in the possible UIP group after 6 and 12 months of pirfenidone treatment (P = .149, 0.026, and 0.025, respectively). The annual decrease in FVC was not significantly different between the 2 groups, and the annual decrease in %DLCO in the UIP group was significantly higher than that in patients with the possible UIP type (-7.767 ± 12.797 vs 0.342 ± 20.358, P < .05). These results indicate that patients with IPF with a possible UIP pattern on HRCT showed indications of a good response to pirfenidone.