EVALUATION OF SPECIFIC AIRWAY CONDUCTANCE AND FLOWS IN ASSESSING BRONCHODILATOR RESPONSIVENESS IN OBSTRUCTIVE AIRWAY DISEASE BY BODY PLETHYSMOGRAPHY
Author: AZEEZ KAHKASHAN, VEERAIAH SHIVAKUMAR
Category: Physiology
Abstract:
Background: Bronchodilator response is routinely assessed during pulmonary function tests to evaluate the therapeutic efficacy. Forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) are the most commonly used parameters. However some studies have shown that bronchodilators may reduce symptoms, independent of any improvement in flows. It has been claimed that direct measurement of airway resistance (Raw) and specific conductance (sGaw) in body plethysmography is more reliable parameter of changes in airway calibre.
Aim: Aim of present work was to assess Raw, sGaw, flows before and after bronchodilator induction and to determine if the measurement of sGaw offers advantages over FEV1 and FVC for the evaluation of bronchoreversiblity.
Methods: Study involved 40 patients with obstructive airway disease. Recordings were done before and 20 minutes after inhaling bronchodilator via a nebulizer. Raw and sGaw were measured in MEC-PFT Systems body plethysmograph along with standard spirometry according to American Thoracic Society standards.
Statistical analysis: Results were analyzed using Mean SD, student-t test in SPSS software version 15.
Results: Out of the 40 patients, seven were excluded who did not meet bronchoreversibilty criteria of FEV1 or FVC or sGaw. The rest 33 patients showed statistical significant improvement i n a ll the p arameters after bronchodilatation. Spirometry alone identified bronchoreversibility in 66.7% of patients and sGaw identified remaining 33.3%.
Conclusion: Changes in spirometric parameters alone lack to reveal significant response to bronchodilator in some obstructive patients. Specific airway conductance must be included in deciding the therapeutic efficacy to obstructive airway disease patients.
Keywords: airway resistance, body plethysmography, specific airway conductance, spirometry, obstructive lung disease.
