Effect of small airway dysfunction on large airway function parameters in elderly adults

BACKGROUND: To investigate the effect of simple small airway dysfunction (SAD) on large airway function parameters in old people. METHODS: Elderly patients aged 60-80 years with complete pulmonary function data including the measured/predicted values of ≥ 80% for each of forced expiratory capacity (FVC), forced expiratory volume in one second (FEV1), and peak expiratory flow (PEF), and FEV1/FVC ≥ 70% were included. Patients with no known smoking history, normal chest computerized tomography, and the measured/predicted values of ≥ 70% for each of maximal flows at 50% and 25% of remaining FVC (MEF50 and MEF25) and maximum mid-expiratory flow (MMEF) were categorized into the control group, whereas patients with the measured/predicted values of < 65% for more than 2 of MEF50, MEF25, and MMEF were divided into the observation group. 104 patients with simple SAD (observation group) and 102 patients with normal pulmonary function (control group) were selected. Except for PEF, the other 5 parameters in the observation group were significantly different from those in the control group. There was no significant difference between total lung capacity (TLC) and functional residual capacity (FRC), but there were significant differences between residual volume (RV), RV/TLC, diffusion capacity for carbon monoxide (DLCO), and specific diffusing capacity (KCO). There were 66 cases of SVC-FVC > 0 (FVC/SVC < 1) (66/104, 63.46%) in the observation group) and 45 cases of the control group (45/102, 44.12%), and the difference between the two groups was statistically significant. The area under the curve (AUC) of SVC-FVC and FVC/SVC in the prediction of SAD was 0.631 and 0.639, respectively, with a sensitivity and specificity of 63%. CONCLUSIONS: Simple SAD was associated with large airway pulmonary function, and PEF may not be a suitable parameter for large airway pulmonary function in the old adults. SVC-FVC > 0.02 L had a certain predictive value for SAD in the elderly.