轻度二氧化碳潴留慢性阻塞性肺疾病肺功能和CT的特征

目的探讨轻度CO₂潴留慢性阻塞性肺疾病人群的肺功及影像特征，为监测和治疗提供依据。 方法选择147例慢性阻塞性肺疾病急性加重期患者，分为非CO₂潴留组61例PaCO₂＝40～44.9 mmHg；轻度CO₂潴留组48例PaCO₂＝45～50 mmHg；呼吸衰竭组38例PaCO₂>50 mmHg，比较3组在肺功能和容积CT参数的异同。 结果轻度潴留组在肺功能参数如一秒率(FEV₁%pred)等和肺气肿参数如肺气肿平均密度(MED)、肺密度分布直方图中第15百分位点所对应的CT值(PD15)等，与呼吸衰竭组存在明显差异(P<0.05)，与非潴留组无统计学差异(P>0.05)。spearman相关分析显示PaCO₂与FEV₁%Pred、FVC%pred呈中度负相关(r分别是-0.536，-0.576，P<0.001)，与PD15和MED存在弱负相关(r＝-0.325，P＝0.002)。 结论轻度CO₂潴留COPD肺结构和功能特征与非潴留COPD相似；呼吸衰竭组COPD具有更严重的病理和肺功能损害；CO₂轻度潴留向Ⅱ型呼吸衰竭进展中，FEV₁%pred等肺功能指标联合PD15和MED影像参数从功能和结构上能更好地反应病情。

Pulmonary functions and imaging features of patients with chronic obstructive pulmonary disease combined with mild carbon dioxide retention

Objective To investigate the pulmonary functions and imaging features of the patients with chronic obstructive pulmonary disease(COPD)combined with mild carbon dioxide(CO2)retention in order to provide evidences for monitoring and treatment of this disease.Methods A total of 147 patients with acute exacerbation of COPD were included for this study.Sixty-one patients with the arterial carbon dioxide tension(PaCO2)of 40-44.9 mm Hg were taken as the no-CO2 retention group,48 patients with PaCO2 of 45-50 mmHg were taken as the mild CO2 retention group,and 38 cases with PaCO2 of more than 50 mmHg were taken as the respiratory failure group.The differences of the pulmonary functions and volume CT were compared between the three groups.Results In the mild CO2 retention group,the pulmonary function parameters such as the percentage of predicted forced expiratory volume in one second(FEV 1%pred),CT value corresponding to the 15th percentile of lung density distribution(PD15)and the mean emphysema density(MED)were significantly different from those of the respiratory failure group(P<0.05).Spearman correlation analysis showed that PaCO2 had a moderate negative correlation with FEV 1%pred and the percentage of predicted forced vital capacity(FVC%pred,r=-0.536 and-0.576,respectively,P<0.001)and a weak negative correlation with PD15 of the whole lungs(r=-0.325,P=0.002)and the MED of the whole lungs(r=-0.333,P=0.002).Conclusion The structure and functional characteristics of the COPD patients with mild CO2 retention are similar to the COPD patients with no CO2 retention.The COPD patients with PaCO2>50 mmHg suffer from more severe pathological and pulmonary function damage.In the progression of mild CO2 retention to typeⅡrespiratory failure,the pulmonary function parameters combined with PD15 and MED may better reflect the disease.