METHODS: The study population consisted of 53 participants, 23 patients with BVFI after endolaryngeal laser posterior cordectomy and 30 healthy volunteers. All of them had body plethysmography (airway resistance, Raw), spirometry (ratio of forced expiratory flow at 50% to forced inspiratory flow at 50%, FEF50/FIF50 and peak inspiratory flow, PIF), 6 min-walking-test (6MWT) and Medical Research Council (MRC) dyspnea scale measurements. The tests were repeated and reliability was evaluated using intraclass correlation (ICC) and Spearman correlation.
RESULTS: The reliability of Raw was high with ICC of 0.92, comparable to the spirometry measurements: FEF50/FIF50(ICC = 0.72) and PIF (ICC = 0.97). The mean of Raw was significantly higher in patient group. A strong significant correlation between Raw and MRC dyspnea scale (r = 0.79; p<0.05) and a moderate negative correlation between Raw and 6MWT (r = 0.4; p<0.05) was demonstrated.
CONCLUSION: Body plethysmography (Raw) is a reliable tool in objective measurement of upper airway resistance that reflects the patient's perception of breathlessness. A larger number of participants are necessary to confirm this finding.