Comparison of pulmonary function test, diffusion capacity, blood gas analysis and CT scan in patients with and without persistent respiratory symptoms following COVID-19

Abstract

Background Long-lasting symptoms following SARS-CoV2-infection have been described in several studies. However, there is only limited knowledge about the ongoing pathophysiology and the association with pathological findings in medical examinations. Methods In this post hoc analysis of a prospective trial, 135 patients following COVID-19 were enrolled and grouped with respect to the presence or absence of respiratory ongoing symptoms following COVID-19. Pulmonary function test (PFT), diffusion capacity measurement (TLCO SB and TLCO/VA), blood gas analysis (BGA), laboratory tests and high-resolution computed tomography (HRCT) of patients with persistent respiratory symptoms were compared to those of asymptomatic patients. Results In this analysis, 71% (96/135) of all patients (mean age 49 years; range 20–91 years) reported long-lasting symptoms after a median (IQR) of 85 days (60–116) following COVID-19 whereby 57.8% (78/135) complained about persistent pulmonary symptoms. Pathological findings in blood test, PFT, TLCO, BGA and/or HRCT were found in 71.8% and 64.1% of patients with and without long-lasting respiratory symptoms respectively. Patients with persistent respiratory symptoms were significantly younger and presented a significant lower FVC (%), TLC (L), and TLCO SB compared to asymptomatic patients (p < 0.05). The multiple logistic regression results in a significant effect of age (p = 0.004) and TLCO SB (p = 0.042). Conclusion Following COVID-19, a large proportion of patients experience ongoing symptoms, whereby the respiratory symptoms are the predominant complaints. Compared to asymptomatic patients, patients with ongoing symptoms were younger and presented a significant lower FVC, TLC and TLCO SB. The multiple logistic regression demonstrated only a significant association between the TLCO SB as the only PFT parameter and the perceived symptoms.

Pulmonary function and survival one year after dupilumab treatment of acute moderate to severe COVID-19: A follow up study from a Phase IIa trial

“…Interestingly we did not see a difference in reported symptoms, neurocognitive assessments, and CT findings between the two treatment groups as we might have expected given the differences found in PFTs. Inconsistencies between subject perception of post COVID-19 symptoms and measured pulmonary function measures has also been demonstrated in other post COVID-19 studies 25,33,40 . As our study subjects did not have pre COVID assessments of these parameters for comparison, a possible explanation may be due to our inability to capture relative change in symptoms and PFTs from baseline measures.…”

Pathophysiological mechanisms in Long Covid: A mixed method systematic review

“…In this review, LC patients with persisting dyspnoea, cough and chest pain following COVID-19 infection were found in a case-controlled study to have signi cantly lower FVC%, TLC% and DLCO% compared to controls. 79 Other studies also demonstrated similar ndings. 38,54,65 Impaired gas transfer was also demonstrated by Xenon MRI scanning in LC patients many months after the acute infection in both hospitalised and nonhospitalised patients despite normal CT imaging of the lungs.…”

Pulmonary function three to five months after hospital discharge for COVID-19: a single centre cohort study

“…The number of studies on the frequency and relevant predictors of COVID-19 related pulmonary sequelae is still limited with varying results 11 , 13 , 15 – 22 . Studies are restricted by small sample sizes, lack of systematic recruitment or an assessment of pulmonary function within 0–6 weeks after discharge, which impedes the distinguishability between ongoing acute inflammation and longer-term consequences 23 – 26 .…”