key: cord-0968591-dfjimds3
authors: Hussain, Aqeel; Khurana, Alkesh Kumar; Goyal, Abhishek; Soman, Raj Krishnan
title: Pulmonary rehabilitation in Covid pneumonia sequelae: so near yet so far
date: 2021-07-09
journal: ERJ Open Res
DOI: 10.1183/23120541.00398-2021
sha: f94839bd930b43081bd205bb887bca3bcacaf776
doc_id: 968591
cord_uid: dfjimds3

We read with great interest the article by Gloeckl et al. whereby they have done an interesting study to evaluate the effect and feasibility of Pulmonary Rehabilitation (PR) in Covid patients [1]. However, we feel that a few pertinent issues need to be highlighted and addressed. Covid-19 associated chronic health issues can persist for prolonged period after recovery from acute illness and has been termed as long covid. However the literature suggests that CT changes and associated lung function impairment show resolution with time [2].

We read with great interest the article by Gloeckl et al whereby they have done an interesting study to evaluate the effect and feasibility of Pulmonary Rehabilitation (PR) in Covid patients. [1] However, we feel that a few pertinent issues need to be highlighted and addressed. Covid-19 associated chronic health issues can persist for prolonged period after recovery from acute illness and has been termed as long covid. However the literature suggests that CT changes and associated lung function impairment show resolution with time. [2] Firstly, to determine the effect of any intervention in presence of spontaneous recovery, a control group representative of the patient population is needed. Post covid patients who could not be offered PR because of barriers like patient refusal, language difficulties could have been enrolled as controls and followed over time to compare their improvement with the PR group. The relevance of having a control group in this study is even more as the improvement in Six minute walk distance (6MWD) in this study can be attributed to multiple confounding factors like spontaneous improvement in lung function, increased motivation at the time of completion of PR and learning effect rather than claiming it solely to be the effect of PR. In mild-moderate group, a 7.7% increase in FVC was seen and in severe-critical group 11.3% increase in FVC was seen. As a positive correlation between FVC and 6MWD is well documented in literature [3, 4, 5] , the increase in 6MWD can be contributed at least in part to the spontaneous improvement in the lung function. This is even more relevant in the mild-moderate subgroup where the improvement in Thirdly, the subset of patients in mild/moderate group did not even require oxygen supplementation and considering them for rehabilitation on the basis of symptoms of dyspnoea, fatigue, cough, cognitive impairment only without significant functional limitation needs a second thought. As per previous studies, the median 6MWD for healthy men is approximately 580 m and for healthy women is 500m. [7] The 83% of patients in the mildmoderate group in this study were females(20 out of total 24) and the mean 6MWD of this group mentioned is 509m. The baseline values of 6MWD in the mild/moderate group were almost in the normal range and so in this group the difference observed in the 6MWD can be attributed to usual variability seen in 6MWD rather than effect of PR. A baseline almost normal 6MWD is obviously expected to result in suboptimal increase after PR intervention. As Ryerson et al had shown that in ILD a baseline significantly decreased 6MWD is a predictor of improvement in 6MWD with PR (r=-0.49, p<0.0005). [8] Therefore expecting a normal 6MWD to increase after an intervention when it is normal/near normal at baseline does not look feasible. The lack of any significant effect of PR on the prevalence of covid symptoms (dyspnoea, fatigue, cough, cognitive impairment) assessed by interviewing the patients after PR further challenges the rationale of considering this particular cohort for benefits of PR.

Lastly, PR services offered to patients differed from the standard practice followed in other respiratory diseases in both the mode and duration of PR program. PR services are usually offered for at least 6 weeks as an out-patient program rather than only for 3 weeks as an inpatient program as offered in this study. Previously PR of 4 weeks has been studied and found to be less effective than 7 week PR even in COPD where the benefits of PR are larger in magnitude as compared to any other chronic respiratory diseases. [9] So a duration of 3 weeks only seems too little to determine the effects of any intervention on parameters assessed.

We do appreciate the authors for exploring this new dimension of management of Covid patients but the above mentioned points need to be addressed before the results are imbibed in their true sense. The realistic application of an old tool of PR in a new disease of Covid pneumonia needs further research in a more planned and comprehensively designed study.

Benefits of pulmonary rehabilitation in COVID-19: a prospective observational cohort study

Pulmonary Function and Radiologic Features in Survivors of Critical COVID-19: A 3-Month Prospective Cohort

Correlation between Six Minute Walk Test and Spirometry in Chronic Pulmonary Disease

Six minute walk test in respiratory diseases: A university hospital experience

Correlation of Six Minute Walk Test with Spirometry and DLCO in Chronic Respiratory Diseases

ATS Committee on Proficiency Standards for Clinical Pulmonary Function Laboratories. ATS statement: guidelines for the six-minute walk test

Reference equations for the six-minute walk in healthy adults

Pulmonary rehabilitation improves long-term outcomes in interstitial lung disease: a prospective cohort study

A randomised controlled trial of four weeks versus seven weeks of pulmonary rehabilitation in chronic obstructive pulmonary disease