Respiratory Muscle Strength and its use in COVID-19 pandemic: Role of Lung Function tests (Preprint)
Authors: Agrawal Dr. Anita , Nalgilkar Vivek 
Published: July 2020

BACKGROUND

There is a concern that pulmonary function testing could represent a potential way for COVID 19 transmission due to the congregation of patients with lung disease and because of the potential for coughing and droplet formation surrounding pulmonary function testing procedures There remain many unknowns facts about the possibility of transmission and the data are in evolution; however, the risks of transmission may be significant, and likely to vary based on the prevalence of the virus in the community and the age and severity of lung disease.
Pulmonary functions routinely used for screening the COVID 19 patients are pulse oximeter and arterial blood gas analysis techniques. In addition to these two, the impaired respiratory muscle performance can also be tested. It is an underappreciated factor contributing to poor outcomes unfolding during the coronavirus pandemic. While impaired respiratory muscle performance is considered to be rare, it is more frequently encountered in patients with poorer health. The primary aim of this study is to discuss the potential role of respiratory muscle performance from the perspective of the coronavirus pandemic.
We have done studies on COPD patients where the impaired respiratory muscle performance is reduced and when we compare that with control group, we realize that this is a good test to identify for COVID 19 patients.

OBJECTIVE

The purpose of this paper is to discuss the potential role of testing respiratory muscle performance. It can be utilised for screening large population during COVID-19 pandemic.

METHODS

This work was done at a Premier Medical Institute of Mumbai, which is a tertiary care centre catering to a large number of patients from all over Mumbai and also other parts of the state of Maharashtra. After proper diagnosis from the Chest Physician and labelled as COPD patient, the MIP measurements was conducted. Spirometry was done during the routine procedure.

RESULTS

In total, 90 subjects with a mean age of 60.3 ± 14.76 years and percentage of forced expiratory volume in 1 second (FEV1) of 89.67+9.92 L were recruited. MIP was significantly higher in control group than COPD. (z=-12.5). The analysis of variance (ANOVA) showed significant difference for maximal inspiratory pressure (p=0.003) between different stages of COPD. The MIP results showed that there was a statistically significant difference between mild and very severe (p=0.0019) as well as between moderate and very severe (p=0.002). The MIP results showed that there was a statistically significant difference between mild and very severe (p=0.0019) as well as between moderate and very severe (p=0.002). A significant positive correlation among maximal static pressure and FEV1 % (r= 0.5) was also observed. MIP thus is an effective technique to measure reduced performance of respiratory muscle strength.

CONCLUSIONS

In addition to pulse oximeter and arterial blood gas analysis, MIP can be the test of choice to test the impaired respiratory muscle performance in COVID 19 patients. Screening for respiratory muscle impairment in patients with dyspnea or characteristics associated increased risk of severe respiratory complication due to viral infection may be advantageous.