Effect of Respiratory Exerciser on Pulmonary Functions of COVID-19 Patients, A Prospective Observational Study
Conditions: Covid19, Respiratory Function Loss, Coronavirus Infection, Pneumonia, Viral
Sponsor: Diskapi Yildirim Beyazit Education and Research Hospital

 
Title Page 
Type of Article: Prospective Observational 
Manuscript Title: Effect of Respiratory Exerciser on Pulmonary Functions of 
COVID-19 patients; A Prospective Observational Study 
Running Head: Respiratory Exerciser on COVID-19 
Document Date: 08.02.2021 
NCT Number: 04826731  
Authors 
Yasemin Aydın1, Emergency Medicine Specialist, MD, ysmnyaydin@gmail.com, 
ORCID:  
Aynur Yurtseven1, Emergency Medicine Specialist, MD, aynuryurt7@gmail.com, 
ORCID: 0000-0002-1554-0873 
Kerem Ensarioğlu2, Pulmonary Medicine Resident, MD, 
kerem.ensarioglu@gmail.com, ORCID: 0000-0002-0968-1549 
Bahar Kurt2, Pulmonary Medicine Specialist, Professor, MD, baharkurt@yahoo.com, 
ORCID: 0000-0002-3495-2339 
1Emergency Medicine Department, Faculty of Health Sciences Dışkapı Yıldırım 
Beyazıt Training and Research Hospital, Ankara, Turkey 
2Pulmonary Medicine Department, Faculty of Health Sciences Dışkapı Yıldırım 
Beyazıt Training and Research Hospital, Ankara, Turkey 
 

Introduction 
SARS-CoV-2 is a novel coronavirus that is responsible for the current pandemic. Its 
clinical presentation varies from asymptomatic infection to severe respiratory failure requiring 
intensive care stay. In earlier studies, loss of respiratory function had been observed in 
survivors of other coronaviruses. The degree of respiratory function loss and if any 
intervention may reduce or prevent it remains an issue to be clarified. 
 
The study aimed to investigate the effects of pulmonary rehabilitation via a supporting 
device on COVID-19 patients during a follow-up period of one month. The primary method 
of investigation of pulmonary functions was comparing peak expiratory flow (PEF) at the 
time of diagnosis and after treatment. 
 
 The study hypothesized that patients who had successfully used a respiratory 
exerciser or a similar aid device would have better PEF results at the end of the first-month 
evaluation. 
 
 
 
 
 
 
 

 
Methods 
The study was performed in Faculty of Health Sciences Dışkapı Yıldırım Beyazıt 
Training and Research Hospital Pulmonary Medicine Department. The local ethics committee 
approved the study with decision number 10/4 and the decision date of 08.02.2021. As a 
prospective study, the first patient admission began on March 29th, and The study completion 
date was accepted as of June 30th, which was the last date for patient admission. All follow-
up evaluation was performed one month after hospital discharge.  
 
Patients were selected among those who had applied to emergency service and 
evaluated by a pulmonary medicine resident or specialist. The general population of the study 
was made from the patients whose hospital admission to the COVID-19 ward was required 
after pulmonary medicine evaluation requested by an emergency medicine specialist. 
Inclusion criteria were being over 18 years old, approval given both written and orally for 
participation, COVID-19 positivity proven by reverse transcription-polymerase chain reaction 
(RT-PCR) testing, and deemed suitable for pulmonary function testing by a pulmonary 
medicine specialist. Exclusion criteria were planned mostly for optimal function testing, 
which included any pathological findings that impede pulmonary function testing such as 
chest deformity, an additional persistent pulmonary pathology that would prevent hospital 
discharge even after COVID-19 treatment, known severe pulmonary function loss 
(characterized by a FEV1 of %30 or less or being unable to participate in respiratory function 
testing), persistent COVID-19 findings which may affect respiratory functions (characterized 
by being bedridden or extended stay requirement due to desaturation not responding to nasal 
oxygen therapy) and former COVID-19 history.   
 

Due to ethical considerations and the assumption that respiratory physiotherapy 
performed by the respiratory exerciser would be beneficial, all patients accepted into the study 
were offered enlistment to the treatment group. Those willing to participate in the study but 
refused device usage were accepted as the control group. Patients in the treatment group were 
asked to use the respiratory exerciser at least four times per day, with each session not lasting 
longer than 10 minutes and with at least an hour in between sessions. 
 
Regardless of suitability for the study, all patients undergo a respiratory function test 
evaluation at the end of the first month, as per routine hospital approach to COVID-19 
patients requiring hospital admission. The follow-up results of those who had participated 
were recorded from this evaluation. Additional follow-up was performed as a part of routine 
COVID-19 follow-up, such as an RFT at three months; however, these results were not a part 
of this study and thus were not accessed or recorded. 
 
PEF, as both percentile and absolute value change, was accepted as the study's primary 
outcome. Mortality was considered as the secondary outcome parameter. The presence of 
known respiratory diseases was accepted as the main confounding parameter, and thus, as 
defined earlier, patients with known respiratory limitations had to be removed from the study. 
Other comorbidities were evaluated by Charlson Comorbidity Index (CCI). Forced Expiratory 
Volume (FEV) and Forced Vital Capacity (FVC) percentages were used to confirm the 
respiratory stability before COVID-19 diagnosis, values of both being over 80% was deemed 
normal. Demographic data was also included due to being required to calculate respiratory 
function thresholds. 
 

Patients' data were retrieved from the hospital record system and from the respiratory 
function testing center. Demographic data, treatment modalities, and evaluation dates were 
also evaluated from electrical patient files from the hospital record system. Initial PEF results 
were taken from the patients' personal peak flow meter devices, and the final results were 
recorded from both hospital spirometer results and personal devices. Retesting was performed 
when a difference above 10% was observed between two different methods. If a difference 
was to be observed again, the result from the patient's device was accepted as the end result. 
 
Selection bias was the main expected bias, and it was expected to be lessened by 
offering participation to all patients admitted to the COVID-19 ward. However, due to the 
study design, patients whose status was considered stable for outpatient treatment were 
excluded, which was expected to affect the results in favor of the treatment group. Additional 
treatment requirements were also considered another source of bias, as patients admitted to 
the COVID-19 ward often received more intensive treatment than outpatient regimens. 
However, the treatment regimen given to those admitted to the ward, which the study 
population consisted of, was assumed to be the same. Similarly, a combination of 
comorbidities was also considered another bias that might hinder a patient's ability to 
participate in respiratory testing, regardless of former capacity; thus, Charlson Comorbidity 
Index (CCI) was used to investigate comorbidities and ensure that comorbidities are present 
that patients remain within an acceptable range. 
 
A total of 50 patients were assumed to be recruited into the study, with an even 
distribution between control and treatment groups. Excluding respiratory function test results, 
no further quantitative variable grouping was performed. 

Descriptive analyses were utilized for data presentation. Nonparametric testing was 
utilized due to non-standard distribution and reduced sample size. Mann-Whitney U test was 
used to evaluate the distribution patterns between groups. Spearman's rho was utilized for 
correlation analysis. No subgroup analyses were planned for the study. If a patient had a 
missing PEF value for any reason, the patient would be removed from the study regardless of 
other values. As the second value of PEF would be recorded at the follow-up, any loss to 
follow-up would also be a reason for exclusion. IBM SPSS Statistics 25th Edition was used as 
the statistical program.