University of Central Florida School of Medicine and Division of Critical Care, Florida Hospital, Orlando, FL, USA.
, PO Box 953814, Lake Mary, FL, 32795, USA.
BMC Pulm Med. 2017 Aug 25;17(1):117. doi: 10.1186/s12890-017-0454-y.
Lung diffusing capacity for carbon monoxide (DLCO) gives an overall assessment of functional lung surface area for gas exchange and can be assessed using various methods. DLCO is an important factor in exercise intolerance in patients with chronic obstructive pulmonary disease (COPD). We investigated if the intra-breath (IBDLCO) method may give a more sensitive measure of available gas exchange surface area than the more typical single breath (SBDLCO) method and if COPD subjects with the largest resting DLCO relative to pulmonary blood flow (Qc) would have a more preserved exercise capacity.
Informed consent, hemoglobin, spirometry, SBDLCO, IBDLCO, and Qc during IBDLCO were performed in moderate to severe COPD patients, followed by progressive cycle ergometry to exhaustion with measures of oxygen saturation (SaO) and expired gases.
Thirty two subjects (47% female, age 66 ± 9 yrs., BMI 30.4 ± 6.3 kg/m, smoking hx 35 ± 29 pkyrs, 2.3 ± 0.8 on the 0-4 GOLD classification scale) participated. The majority used multiple inhaled medications and 20% were on oral steroids. Averages were: FEV/FVC 58 ± 10%Pred, peak VO 11.4 ± 3.1 ml/kg/min, and IBDLCO 72% of the SBDLCO (r = 0.88, SB vs IB methods). Using univariate regression, both the SB and IBDLCO (% predicted but not absolute) were predictive of VOpeak in ml/kg/min; SBDLCO/Qc (r = 0.63, p < 0.001) was the best predictor of VOpeak; maximal expiratory flows over the mid to lower lung volumes were the most significantly predictive spirometric measure (r = 0.49, p < 0.01). However, in multivariate models only BMI added additional predictive value to the SBDLCO/Qc for predicting aerobic capacity (r = 0.73). Adjusting for current smoking status and gender did not significantly change the primary results.
In patients with moderate to severe COPD, preservation of lung gas exchange surface area as assessed using the resting SBDLCO/Qc appears to be a better predictor of exercise capacity than more classic measures of lung mechanics.
一氧化碳肺弥散量（DLCO）可全面评估用于气体交换的功能性肺表面面积，可使用多种方法进行评估。DLCO 是慢性阻塞性肺疾病（COPD）患者运动不耐受的重要因素。我们研究了呼吸内（IBDLCO）法是否比更典型的单次呼吸（SBDLCO）法更能敏感地测量可用气体交换表面积，以及 DLCO 与肺血流量（Qc）比值最大的 COPD 患者是否具有更保留的运动能力。
在中度至重度 COPD 患者中进行知情同意、血红蛋白、肺活量测定、SBDLCO、IBDLCO 和 IBDLCO 期间的 Qc，然后进行渐进性踏车运动直至力竭，测量氧饱和度（SaO）和呼出气体。
32 名受试者（47%为女性，年龄 66±9 岁，BMI 30.4±6.3kg/m，吸烟史 35±29 pkyrs，0-4 GOLD 分类量表上 2.3±0.8）参与了研究。大多数患者使用了多种吸入药物，20%患者使用口服类固醇。平均值为：FEV/FVC 58±10%预测值，峰值 VO 11.4±3.1ml/kg/min，IBDLCO 为 SBDLCO 的 72%（r=0.88，SB 与 IB 方法）。使用单变量回归，SB 和 IBDLCO（%预测值但不是绝对值）均可预测 VOpeak 以 ml/kg/min 为单位；SBDLCO/Qc（r=0.63，p<0.001）是 VOpeak 的最佳预测指标；中至下肺容积的最大呼气流量是最具预测性的肺功能测量指标（r=0.49，p<0.01）。然而，在多变量模型中，只有 BMI 为 SBDLCO/Qc 预测有氧运动能力增加了额外的预测价值（r=0.73）。调整当前吸烟状况和性别并没有显著改变主要结果。
在中重度 COPD 患者中，使用静息 SBDLCO/Qc 评估的肺气体交换表面面积的保留似乎比更经典的肺力学测量更能预测运动能力。
