Effects of short-term breathing exercises on respiratory recovery in patients with COVID-19- a quasi-experimental study


 Background:Coronavirus disease 2019 (COVID-19) is a highly infectious respiratory tract disease. The most common clinical manifestation of severe COVID-19 is acute respiratory failure. Respiratory rehabilitation can be a crucial part of treatment but data lack for patients with COVID-19. This study investigates the effects of short-term respiratory rehabilitation (i.e., breathing exercises) on respiratory recovery among hospitalised patients with COVID-19. Methods: This quasi-experimental, pre-post-test study recruited 110 patients hospitalised with COVID-19. All patented received standardised care, and 65 patients also received the intervention (i.e., breathing exercises). Data on peripheral oxygen saturation (SpO2), respiratory rate (breaths/minute) and heart rate (beats/minute) and oxygen therapy requirement (litre/min) were collected at baseline and 4-5 days after the baseline assessment. Analysis of variance on repeated measures was applied to compare the outcomes of two-time points. Results: The mean (±Standard deviation, SD) age of the intervention group was 49.5 (±10.4) years and 73.8% were men. The mean (±SD) age of the control group was 49.3 (±7.9) years and 62.2% were men. After 4-5 days of respiratory rehabilitation SpO2 (96.7% ±2.1 vs 90.4% ±1.5), P<0.01), respiratory rate (20.5 ±2.4 vs 23.0 ±2.2) breaths/minute, P<0.01), heart rate (80.5 ±9.2 vs 91.2 ±8.6) beats/minute, P<0.01), and oxygen therapy requirement (0.4 ±0.98 vs 1.4 ±2.0) litre/min, P<0.01) improved in the intervention group compared to the control group. The mean days of hospitalisation for the intervention group and the control group were 7.1 days vs. 14.6 days, respectively. Conclusions:Our results indicate that breathing exercise, even for a short period, is effective in improving certain respiratory parameters in patients with COVID-19. As a non-invasive and cost-effective respiratory rehabilitation intervention, breathing exercise can be a useful tool for a health care system overwhelmed by COVID-19 pandemic. These results should be considered preliminary until they are replicated in larger samples in different settings.

Respiratory rehabilitation is crucial for the recovery of patients with viral pneumonia from COVID-19 during the acute and rehabilitation phase 5 9 . Respiratory rehabilitation includes breathing exercises and respiratory muscle training using diaphragmatic breathing, pursed-lip breathing, relaxation-and body position exercises [10][11][12][13]. Respiratory rehabilitation improves the physical and psychological symptoms of lung disease (e.g., chronic obstructive pulmonary disease (COPD)) as it improves oxygen exchange, prevents the lungs from collapse and strengthen the breathing, and reduces the need for artificial ventilation [10][11][12][13] . Specifically, in patients hospitalised with COVID-19, respiratory rehabilitation reduce complications, improves symptoms of dyspnea, prevent and improve dysfunction and improve quality of life (QoL) 14 . A recent randomised controlled trial of six-week respiratory rehabilitation reported significant improvement to certain respiratory functions (e.g., forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC)), QoL and anxiety in elderly patients with COVID-19 without COPD. At the time of writing, there is a paucity of evidence about the effects of respiratory rehabilitation in the acute stage of COVID-19 treatment and cardiorespiratory recovery in patients with COVID-19 [15][16][17][18] . This is because the respiratory problems experienced by patients with COVID-19 significantly differ from other respiratory conditions (e.g., dry cough is common 4 19 ) and COVID-19 patients' rapid deterioration to acute respiratory failure [2][3][4] . Also, the availability of health resources to treat COVID-19 patients in resource poor setting may be limited. As a cost-effective intervention, the impact of shortterm respiratory rehabilitation on respiratory parameters in COVID-19 patients in resourcepoor settings is not previously established. Therefore, this study aims to examine the effects of short-term breathing exercises on respiratory recovery (i.e., oxygen saturation, respiratory rate (breaths/minute), and heart rate (beats/minute), and oxygen therapy (litre/min)) among hospital-admitted patients with COVID-19. We hypothesised that the breathing exercise intervention would result in significant improvements in the outcome measures.

Study design and participants
We used a quasi-experimental design with pre-post-tests to assess the respiratory rehabilitation intervention in a group of COVID-19 patients 20 . Physiotherapists, nurses, or medical officers screened patients aged between 18-70 years and hospitalised with a laboratory-confirmed COVID-19 with reverse transcription-polymerase chain reaction test for eligibility based on the following recommended criteria 9   The intervention-group received breathing techniques instructions, an all-embracing term for a range of breathing exercises 10 12 in suitable positions. A physiotherapist supervised each session that contained: breathing control, followed by diaphragmatic breathing (5-7 times), thoracic breathing (3-5 times deep breathing +5 sec hold of breath), huffing (forced expiratory technique) coughing (1-2 times) and active respiratory exercises, and breathing control and in some cases, it was followed by using incentive Spirometer (5-7 times) ( Figure 1). b Threre were 3 missing data in the control group, because they were still hospitalized during the data collection

Data collection
Baseline data were collected using hospital-reports. These included demographic data, the level of respiratory support (i.e., oxygen therapy), and presence of any major coexisting illnesses.

Outcomes measures
We collected respiratory clinical parameter (i.e., oxygen saturation, respiratory rate (breaths/minute), and heart rate (beats/minute), and oxygen therapy (litre/min)) at baseline (before the treatment) and at follow-up (4-5 days after the baseline assessment).
The Peripheral oxygen saturation (SpO2) was assessed using the adult finger pulse oximeter PM100C (New Tech ® , EUA), positioned on the hand's fifth finger. The SpO2 indicates the percentage of arterial haemoglobin saturated with oxygen and is a vital sign 23 .
Respiratory rate was assessed by counting the number of breaths/minutes is an early indicator of hypoxia, hypercapnia and metabolic and respiratory acidosis 5 24 .
Heart rate (beats/minute) was assessed by measuring the radial pulse. The regularity of heart rhythm indicates the strength of heart contraction and sufficiency of cardiac output.
Oxygen therapy requirement (litre/min) was recoded. Face mask was used to deliver 2-10 litre/min of oxygen and nasal cannulae was used to deliver 4 litre/min of oxygen.

Patient and public involvement
Patients were not involved in the design, conduct or interpretation of the study.

Statistical analysis
Descriptive statistics were computed for all the variables. Continuous variables were expressed by means and standard deviation (SD) and tested using independent t-test between groups. Categorical variables were described as frequency and percentage and tested using Chi-square test between groups. The sample of each group was large enough and comparisons were not affected by the shape of the error distribution and no transformation was applied 25 .
A two-way analysis of variance on repeated measures (with Bonferroni post hoc adjustment), and paired t-test on each intervention or control group applied to compare the outcomes of each of the three respiratory parameters of two-time points. The number of participants to be included in the study was determined by Power analysis done in G*Power (version 3.1.9.4.).
An a priori power analysis for a repeated-measures analysis of variance with two repeatedmeasures showed that total 98 participants would require to get a statistical power (1-β err prob) of 80%.
All reported P-values are based on two-sided tests, with a P-value of less than .05 considered as significant. All the data were analysed using the IBM SPSS Statistics for Windows (IBM Corporation, Released 2019, Armonk, 137 New York, United States)

Participant Characteristics
The

Discussion
One of the key findings was that SpO2, respiratory rate and heart rate improved in patients with COVID-19 who received breathing exercise while reducing their need for oxygen therapy. We initially hypothesised that respiratory parameters would improve in both intervention and control groups, with the intervention group demonstrating more significant improvements. This was because respiratory rehabilitation improves respiratory muscle function, ribcage flexibility, ventilation, and gas exchange, consequently helping patients with COVID-19 to manage their respiratory symptoms 23 . Both scientific and anecdotal reports have highlighted the importance of breathing exercise for maintaining respiratory function [15][16][17][18] . In a randomised controlled trial, elderly patients (aged ≥ 65) with COVID-19 without COPD improved their SpO2 following respiratory rehabilitation 26 and our findings concur.
Given the high respiratory impairment burden following the acute phase of COVID-19, patents should be referred early to a respiratory rehabilitation programme, particularly those admitted to a hospital. Another key finding was that the length of hospital stay had halved (mean 7.1 days vs. 14.6 days) for patients who received respiratory rehabilitation. intensive care, has placed unprecedented strain on the health system across the globe.
Determining health care resources such as beds, staff, equipment and therapeutic is a key priority for many countries as the COVID-19 escalate. Respiratory rehabilitation is noninvasive, safe, and easy to implement and cost-effective. Health care system are overwhelmed in many countries; respiratory rehabilitation reduces the length of hospital stay, thus provide some respite. Given the risk of infection, physiotherapists and other health care staff administering respiratory rehabilitation need to take appropriate steps such as wearing personal protective equipment to protect themselves from droplet contamination by coughing and sneezing during breathing exercises.

Clinical Implications
In patients with COVID-19, low blood oxygen levels are associated with rapid deterioration to acute respiratory distress or failure, leading to death unless it is managed immediately 2-4 .
We found that respiratory rehabilitation during the acute phase of care improves SpO2, respiratory rate and heart rate in patients hospitalised with COVID-19. Our study provides guidance for the delivery of quality respiratory care to patients with COVID-19. Respiratory rehabilitation can be implemented safely. However, appropriate infection control strategies must be employed to prevent droplet contamination by coughing, sneezing, and close contact with a COVID-19 patient's during treatment. Typically, a non-productive cough is associated with COVID-19, productive coughing may appear at a later stage 29 . Therefore, as a precaution, airways should be regularly cleared to remove bronchial secretions. Only medically stable patients should be considered for respiratory rehabilitation as recommendations by the Chinese, Netherlands, Italian, and UK rehabilitation professionals 5 10 15 17 30 . Further, individualised approach to respiratory rehabilitation led by a multidisciplinary team (e.g., physician, physiotherapist and occupational therapist, nurses) can increase positive outcomes 5 15 30 . However, given the highly contagious nature of the SARS-CoV-2, robust respiratory rehabilitation plan must be in place to make optimal use of a limited rehabilitation workforce and reduce risk to health professionals.

Strength and limitation:
Key strengths of this study are methodological rigour, using quasi-experimental design when it was not logistically feasible or ethical to conduct a randomised controlled trial. Like the randomised controlled trial, the quasi-experimental design can establish causal associations between an invention and an outcome 31 . Representative sample size from both sexes and socio-demographic background (e.g., educational level, employment), with broad age groups (18-70 years) is another strength. Further patients with COVID-19 were not excluded based on pre-specified comorbidities (e.g., COPD). Thus, our findings apply to similar populations.
Study participants were recruited from four tertiary hospitals from Bangladesh, the intervention group from one hospital and control group from other three hospitals. Therefore, resource availability might differ between hospitals; however, standardised care provides all patients according to the National Guidelines on Clinical Management of COVID-19 22 . Only the short-term effects (4-5 days) were evaluated and a limitation of our data.

Conclusions
Breathing exercise as a part of respiratory rehabilitation improved respiratory parameters in patients hospitalised with COVID-19. Also, the length of hospital stay was reduced by half in the patents who received breathing exercise. These results should be considered preliminary until they are replicated in larger samples in various settings. Further studies are also needed to determine the long-term effect of breathing exercises on the overall respiratory functions in patients with COVID-19. However, as a non-invasive and cost-effective intervention, breathing exercise is a useful tool for a health care system are overwhelmed by COVID-19 pandemic.