PURPOSE: To identify patients of bronchial asthma (suspected), not responding to optimal therapy, for the presence of vocal cord dysfunction (VCD) and to compare the diagnostic ability of FV (Flow Volume) loop and impulse oscillometry (IOS).
METHODS: Fifty-one patients of suspected/proven bronchial asthma not responding to optimal therapy were included for study. Each patient was subjected to both FV loop and IOS. Direct visualization of the vocal cords with flexible fiberoptic bronchoscope for the presence of inspiratory vocal cord adduction during quiet respiration, speech and performing provocative maneuvers was done. Participants were subjected to simple pulmonary function tests and FV loop. IOS was performed on each patient to look for site of obstruction and upper airway influence. The observations of both FV loop and IOS studies were compared.
RESULTS: Among 51 patients, 12 (23.53%) had bronchoscopical evidence of VCD and labeled as VCD+ve group and rest of 39 were designated VCD-No statistically significant difference in pulmonary function test (pre-reversibility) results between the VCD+ve and VCD-ve patients was found. Reversible airway obstruction was observed in 75% of the patients of VCD+ve group and 67.65% of the patients in the VCD-ve group. Only one patient in the VCD+ve and none in VCD-ve group had inspiratory limb flattening of FV loop. Upper airway influence was evident by IOS in 58.3% of patients in the VCD+ve group and in 15.4% of patients in the VCD-ve group. This difference was statistically significant (p<0.005).
CONCLUSION: VCD was a common finding in patients with symptoms suggestive of asthma and frequently co-exists. IOS was found to be a useful screening test for VCD and was more sensitive than FV loop.
CLINICAL IMPLICATIONS: IOS has not been used in the evaluation of VCD until now. Our results indicate that IOS can be a useful screening tool for suspected VCD cases. In addition, IOS offers certain advantages over spirometry as it is effort independent, consumes less time and requires minimal patient cooperation.
DISCLOSURE: Harmanjit Hira, No Financial Disclosure Information; No Product/Research Disclosure Information