慢性阻塞性肺疾病患者运动高峰时肺内气体交换对运动能力的影响

目的 探讨COPD患者在运动高峰时肺内气体交换对最大运动能力的影响.方法 对42例男性稳定期COPD患者及26例健康男性进行功率递增至症状自限的踏车运动,同步实时测定摄氧量和二氧化碳产生量,在运动高峰时抽取桡动脉血,测定并计算PaO2、PaCO2、死腔容积与潮气容积比值(VD/VT)和P(A-a)O2.分别对两组资料进行正态性检验,符合正态分布的资料以x-±s表示,两组间比较采用独立样本t检验,最大摄氧量与运动高峰时的血气参数进行相关因素分析.结果 COPD组的最大摄氧量(16±4)ml·kg-1·min-1]明显低于对照组(19±6)ml·kg-1·min-1];PaCO2(43±3)mm Hg,1 mm Hg=0.133 kPa]、VD/VT(0.35±0.11)和P(A-a)O2(33±11)mm Hg]均明显高于对照组(40±5)mm Hg、0.27±0.08和(15±7)mm Hg];最大摄氧量与VD/VT呈显著负相关(r=-0.734,P＜0.01).结论 VD/VT增加导致通气效率降低,这是引起COPD患者运动能力减低的一个重要原因.

Effect of gas exchange at maximal intensity on exercise capacity in patients with chronic obstructive pulmonary disease

Objective To investigate the effect of gas exchange at maximal intensity on exercise capacity in patients with chronic obstructive pulmonary disease(COPD).Methods Forty-two male patients with COPD and 26 normal subjects performed incremental exercise test on cycle ergometer.Oxygen uptake and carbon dioxide output were measured continuously on the breath-by-breath mode.Arterial blood samples were drawn at maximal exercise.PaO2,PaCO2,the actual dead space/tidal volume ratios(VD/VT)and the alveolar-artefiM PaO2 difference P(A-a)O2] were measured and calculated.Comparisons between the two groups were performed using independent samples t test.Linear regression analyses were made between P(A-a)O2,VD/VT and PaCO2 were greater in patients (43±3)mm Hg,1 mm Hg=0.133 kPa,0.35±0.11,(33±11) mm Hg]than in normal subjects at peak exercise (40±5) mm Hg,0.27±0.08,0.01).Conclusion The increase in VD/VT inducing ventilatory inefficiency during exercise is one of the important causes for decreased exercise capacity in patients with COPD.