Impaired pulmonary function in discharged patients with COVID-19: more work ahead

Abstract

Abnormal carbon monoxide diffusion capacity in COVID-19 patients at time of hospital dischargeTo the Editor: I have read with great interest the article by MO et al. [1] entitled "Abnormal pulmonary function in COVID-19 patients at time of hospital discharge" recently published in the European Respiratory Journal. In this study, the authors describe pulmonary function tests in patients who suffered from coronavirus disease 2019 (COVID-19), which were performed on discharge from hospital. Patients were classified into three groups of severity. In the patients who suffered more severely, measured carbon monoxide diffusion capacity (D LCO ) was lower. However, when looking at D LCO /V A , which represents the transfer factor of carbon monoxide, the picture is different. Patients who had severe pneumonia had an average D LCO /V A of 82% of predicted while patients in groups classified as having mild disease or pneumonia had average values above 90%. Notably, all these averages have relatively high standard deviation values (e.g. 13.9% in severe pneumonia), meaning that some patients in the post-severe pneumonia group had a D LCO /V A >90% of predicted.

Alterations in Respiratory Function Test Three Months after Hospitalisation for COVID-19 Pneumonia: Value of Determining Nitric Oxide Diffusion

“…Notwithstanding, this current work reveals the limited concordance between many other RFTs, which may reflect the complexity of the structural involvement in patients who have suffered severe COVID-19 pneumonia. These patients may suffer persistent lesions at the level of the parenchyma, distal airways, and small pulmonary vessels (as endothelitis or microthrombosis), as well as haemodynamic alterations that can compromise the ventilation/perfusion balance, all for varying amounts of time [ 12 , 13 , 14 , 15 , 16 , 17 ]. In addition, patients’ own underlying diseases, the frequent need for high oxygen concentrations for several days (with the consequent risk of hyperoxia), interrelation between different functional parameters (such as the influence of the VA), and variability in performance of each evaluation technique, may also influence the heterogeneity seen in the work published so far [ 12 , 13 , 14 , 15 , 16 , 17 , 30 ].…”

“…Publication of the first studies analysing functional alterations in patients in the first four weeks after discharge from hospitalisation with COVID-19 pneumonia [ 11 ] generated an interesting scientific debate about which value of DL CO that might be used to detect functional alterations, as well as the need to adjust these values according to the alveolar volume (VA). However, more studies will be required to clarify the value of these determinations in the detection of the pulmonary sequelae of this virus [ 12 , 13 ]. Because patients with severe pulmonary involvement or interstitial involvement secondary to COVID-19 may present small vessel endothelial damage and altered pulmonary hemodynamic [ 14 , 15 ], some authors suggested that the combined determination of DL CO along with the diffusion capacity of nitric oxide (DL NO ) could help detect these vascular and interstitial changes in patients recovering after hospitalisation for these processes [ 16 , 17 ], as already described for other pulmonary conditions [ 18 , 19 , 20 ].…”

Post-discharge chest CT findings and pulmonary function tests in severe COVID-19 patients

“…Similarly, in survivors from Middle East respiratory syndrome, 36 % of patients had residual radiographic changes at a median follow-up of six weeks, mostly due to fibrosis [7]. Emerging data on COVID-19 further indicate that the disease can result in prolonged illness and persistent symptoms [10,11], with post-acute PFT and imaging findings that possibly imply a degree of pulmonary vasculopathy and interstitial lung involvement persisting in the recovery phase of the disease [12][13][14][15]. However, to the best of our knowledge, only a few studies have described computed tomography (CT) findings in discharged COVID-19 patients so far [15][16][17], and there are currently no data on the physiological relevance of chest CT abnormalities in COVID-19 survivors.…”

Cardiopulmonary exercise testing might be helpful for interpretation of impaired pulmonary function in recovered COVID-19 patients

“…We are grateful to have the opportunity for an in-depth discussion with Dr Nusair et al [ 1 ]and Dr Chapman et al [ 2 ] who we sincerely appreciate their insightful comments on our study about the impaired pulmonary function in COVID-19 patients [ 3 , 4 ], which helps to interpret the parameters of abnormal lung diffusion capacity more accurate.…”