Analysis of influencing factors of ventilatory efficiency in patients with chronic obstructive pulmonary disease

Objective To analyze the influencing factors of ventilatory efficiency in patients with chronic obstructive pulmonary disease (COPD). Methods Sixty-seven patients with stable COPD were selected to collect age, sex, height, weight and other basic information, calculate body mass index (BMI), perform pulmonary function and cardiopulmonary exercise test, and determine the forced vital capacity (FVC), forced expiratory volume in one second (FEV1), carbon dioxide equivalent ventilation in rest (EqCO2rest), carbon dioxide equivalent ventilation in anaerobic threshold (EqCO2at), carbon dioxide equivalent ventilation in maximum movement (EqCO2max), established multiple linear regression equation to analyze the influencing factors of ventilatory efficiency in patients with COPD. Results (1)The parameters EqCO2rest, EqCO2at and EqCO2max were set as dependent variables Y1, Y2 and Y3 respectively.Sex, age, height, weight and BMI were set as independent variables X1, X2, X3, X4 and X5.Establishing multiple linear regression equation were Y1=47.357-0.505×X5, Y2=46.894-0.202×X4, Y3=43.394-0.527×X5.(2)BMI of COPD patients was negative correlated with EqCO2rest, EqCO2at and EqCO2max (r=-0.430, -0.403, -0.394, all P<0.001). (3)the parameters of patients with COPD in different BMI groups were compared: EqCO2rest in obese group (31.2±4.5) was lower than that in normal weight group (37.6±6.7), and the difference was statistically significant (P=0.001). EqCO2at in obesity group (28.9±4.2) was lower than that in normal weight group (35.1±6.5), and the difference was statistically significant (P=0.001). EqCO2max in obesity group (26.1±3.7) was significantly lower than that in normal weight group (32.8±6.5) and overweight group (30.9±6.4) (P<0.001, 0.016, respectively). (4)There were significant differences compared with EqCO2max and EqCO2rest, EqCO2at in the low weight group (P=0.045, 0.044, respectively), compared with EqCO2rest and EqCO2max in normal weight group and obesity group, and the difference was statistically significant (P=0.007, 0.001 respectively). Conclusions The ventilation efficiency of patients with COPD increases significantly during maximal exercise, and the obesity COPD patients may have higher ventilation efficiency. Key words: Pulmonary disease, chronic obstructive; Cardiopulmonary exercise test; Carbon dioxide equivalent ventilation; Body mass index