Respiratory muscles power reversibility test as a new test in asthma diagnosis

Abstract

Making diagnosis of asthma requires a critical evaluation of the patient’s symptoms, medical history, physical examination and diagnostic tests. It is known that a reduction of respiratory muscle pressures (MIP and MEP) for assessment of respiratory muscles power has been associated with several neuromuscular diseases, but it is also possible to point out lower values in patients with chronic obstructive pulmonary diseases as in asthma. As asthma diagnosis by reversibility test is not very sensitive in intermittent and mild asthma and pulmonary function is related to respiratory muscle pressures (RMP), could we use the reversibility of RMP in the patients for asthma diagnosis is the main issue investigated in this research. The aim of the study to determine the validity of asthma diagnosis by reversibility testing of respiratory muscles power. A cross-sectional hospital based study carried out in Lung function tests clinic in Police and Alban Gadeed hospitals in Khartoum during the years 2010-2011 to determine the reversibility of the lung function (FEV1 and PEFR) and respiratory muscles power (MEP and MIP). Thirty five known asthmatic subjects attending the referred chest clinic for follow up, and 20 healthy non asthmatic controls were included in the study. FEV1, PEFR, MEP and MIP were measured for all subjects before and after bronchodilator. Reversibility test was considered positive assuming the cut-off point for FEV1, MEP and MIP is ≥12% and for PEFR≥20%.The results showed percent of change in asthmatic group before and after bronchodilator test for FEV1 , PEFR, MEP, MIP were: 10.45, 11.84, 12.15 and 16.73 respectively. The difference was statistically significant. Sensitivity and specificity of reversibility testing for FEV1 (40%, 75%), for PEFR (31%, 65%), for MEP (49%, 70%) and for MIP (71%, 65%). In conclusion, the respiratory muscles power reversibility test could be a potentially sensitive diagnostic test for asthma