ObjectiveTo assess the lung capacity and diffusing capacity in patients with chronic obstructive pulmonary disease (COPD) at different stages. MethodsPatients who were diagnosed with COPD between January and March 2015 were recruited in the study. The data of clinical characteristics and spirometry test (the forced expiratory volume in the first second, FEV1) were collected. Total lung capacity (TLC) and residual volume (RV) were determined by body plethysmography and helium dilution method, and single breath diffusing capacity for carbon monoxide (DLCO) was also measured. Lung capacity and the deviations between two methods, and DLCO%pred were compared among the COPD patients at different stages. The correlation of spirometry with lung capacity and DLCO%pred were analyzed. ResultsA total of 170 patients with COPD were enrolled. With the severity of COPD, TLC%pred, RV%pred, RV/TLC and the deviations of the ones between two methods increased significantly, but DLCO%pred reduced significantly. FEV1%pred were negatively correlated with the deviations of lung capacity between two methods, and positively correlated with DLCO%pred. ConclusionsCompared with helium dilution method, the body plethysmography is more accurate for evaluating the lung capacity of COPD. With the severity of airflow limitation, the diffusing capacity of COPD decreases gradually.
ObjectiveTo assess the lung capacity and diffusing capacity in patients with chronic persistent asthma with different severities. MethodsPatients diagnosed with chronic persistent asthma in West China Hospital between January 2014 and April 2015 were recruited in the study.The data of clinical characteristics were collected.The forced expiratory volume in the first second (FEV1) was determined by spirometry test.Total lung capacity (TLC) and residual volume (RV) were determined by body plethysmography and helium dilution method.Single breath diffusing capacity for carbon monoxide (DLCO) was also measured.Lung capacity and the deviations between two methods, and DLCO%pred were compared among different patient groups with mild, moderate and severe asthmas.The correlation between spirometry with lung capacity and DLCO%pred were analyzed. ResultsA total of 93 patients with chronic persistent asthma were enrolled.With the severity of asthma, TLC%pred, RV%pred, RV/TLC and the deviations of the ones between two methods increased significantly, but DLCO%pred reduced slightly.FEV1%pred were negatively correlative with the deviations of lung capacity between two methods, and positively correlative with DLCO%pred. ConclusionsCompared with helium dilution method, the body plethysmography is more accurate for evaluating the lung capacity of chronic persistent asthma.With the severity of airflow limitation, the diffusing capacity of asthma is decreasing gradually, but still within the normal limits.
Objective To observe the changes in pulmonary function in chronic obstructive pulmonary disease (COPD) patients with different GOLD grades, diffusing capacity for carbon monoxide in percent predicted value (DLCO%pred), and the relationship between DLCO%pred and hyperinflation parameter, the ratio of residual volume to total lung capacity (RV/TLC). Methods Their age, sex, body mass index (BMI), and lung function parameters were recorded. Group according to GOLD grade, and compare the lung function among different groups; With DLCO%pred 60% as the cut-off value, the lung function of each group was compared. Pearson and Spearman correlation determined the relationship between DLCO%pred and age, RV/TLC, and other factors. Results Four hundred and thirty-one patients were enrolled. With the increase of GOLD grade, the pulmonary function became worse (P<0.05). Compared with DLCO%pred ≥ 60%, the group with DLCO%pred<60% had lower BMI (t=–5.642, P<0.001) and worse pulmonary function (P<0.001). The correlation analysis showed that BMI (r=0.352, P<0.001), forced vital capacity in percent predicted value (FVC%pred) (r=0.349, P<0.001), forced expiratory volume in one second in percent predicted value (FEV1%pred) (r=0.414, P<0.001), the ratio of forced expiratory volume in one second to forced vital capacity (FEV1/FVC) (r=0.434, P<0.001), peak expiratory flow in percent predicted value (PEF%pred) (r=0.335, P<0.001), maximal mid expiratory flow in percent predicted value (MMEF%pred) (r=0.405, P<0.001), inspiratory capacity in percent predicted value (IC%pred) (r=0.301, P<0.001) were positively correlated with DLCO%pred; while RV/TLC (r=–0.328, P<0.001), GOLD grade (r=–0.430, P<0.001) were negatively correlated with DLCO%pred; However, there was no significant correlation between age (r=–0.012, P=0.810), sex (r=0.076, P=0.117) and DLCO%pred. Conclusions With the increase of GOLD grade, DLCO%pred decreases, and RV/TLC increases. RV/TLC is negatively correlated with DLCO%pred. Attaching importance to the evaluation of hyperinflation and diffusing capacity of COPD patients is helpful in evaluating COPD in all aspects, and has particular clinical significance.