Dreher M, Walterspacher S, Sonntag F, Prettin S, Kabitz H J, Windisch W
Department of Respiratory Medicine, University Hospital Freiburg, Freiburg, Germany.
Respir Med. 2008 Jun;102(6):912-8. doi: 10.1016/j.rmed.2008.01.002. Epub 2008 Feb 14.
It remains unclear whether the 6-min walking test can predict performance during stair-climbing in severe COPD patients. The present study aimed to assess different pathophysiological changes between walking and stair-climbing in these patients.
Sixteen COPD patients (mean FEV1 33+/-13% predicted) underwent a 6-min walking test and performed stair-climbing (44 steps) in a randomized, cross-over design. Blood gases, blood lactate, lung function parameters, maximal inspiratory mouth, sniff nasal and twitch mouth pressures, blood pressure, heart rate, and Borg Dyspnea Scale (BDS) were measured before and after exercise.
The median drop of PaO2 during walking (2.6 mmHg) and stair-climbing (2.4 mmHg) was comparable (p=0.93). However, stair-climbing caused more dyspnea (median BDS 6.5 vs. 5.5, p=0.01), a higher median blood lactate (1.1 vs. 0.3 mmol/l p<0.001), a more pronounced drop in mean pH (-0.05+/-0.02 vs. -0.03+/-0.03, p=0.02) and a higher increase in mean systolic blood pressure (27+/-11 vs. 13+/-16 mmHg; p=0.009). Stair-climbing, but not walking, caused prolonged lung hyperinflation (mean TLC difference 4.4+/-4.7% predicted, p=0.003). There was no relationship between the 6-min walking distance (314+/-104 m) and the time needed for stair-climbing (55+/-33 s), nor were there any differences in inspiratory muscle strength and heart rate.
Although the drop of PaO2 was comparable, stair-climbing resulted in more prolonged hyperinflation of the lungs, higher blood lactate production and more dyspnea than walking. The walking distance was not related to the time needed to manage stair-climbing. Therefore, pathophysiological changes during the 6-min walking test do not anticipate those during stair-climbing in patients with severe COPD.
6分钟步行试验能否预测重度慢性阻塞性肺疾病（COPD）患者爬楼梯时的表现尚不清楚。本研究旨在评估这些患者步行和爬楼梯过程中不同的病理生理变化。
16例COPD患者（预计FEV1平均值为33±13%）采用随机交叉设计进行6分钟步行试验并进行爬楼梯（44级台阶）。在运动前后测量血气、血乳酸、肺功能参数、最大吸气口腔压、嗅鼻压和抽搐口腔压、血压、心率以及Borg呼吸困难量表（BDS）。
步行时（2.6 mmHg）和爬楼梯时（2.4 mmHg）动脉血氧分压（PaO2）的中位数下降相当（p = 0.93）。然而，爬楼梯导致更严重的呼吸困难（BDS中位数6.5对5.5，p = 0.01）、更高的血乳酸中位数（1.1对0.3 mmol/L，p < 0.001）、平均pH值更明显下降（-0.05±0.02对-0.03±0.03，p = 0.02）以及平均收缩压更高的升高幅度（27±11对13±16 mmHg；p = 0.009）。爬楼梯而非步行导致肺过度充气时间延长（预计总肺容量平均差异4.4±4.7%，p = 0.003）。6分钟步行距离（314±104 m）与爬楼梯所需时间（55±33 s）之间没有关系，吸气肌力量和心率也没有差异。
尽管PaO2下降相当，但与步行相比，爬楼梯导致肺过度充气时间延长、血乳酸生成增加以及更严重的呼吸困难。步行距离与爬楼梯所需时间无关。因此，6分钟步行试验期间的病理生理变化无法预测重度COPD患者爬楼梯时的变化。
