Donahoe M, Rogers R M, Wilson D O, Pennock B E
Department of Medicine, University of Pittsburgh School of Medicine, PA 15261.
Am Rev Respir Dis. 1989 Aug;140(2):385-91. doi: 10.1164/ajrccm/140.2.385.
Patients with severe chronic obstructive pulmonary disease (COPD) commonly experience weight loss. An increased energy expenditure for respiration might explain the increased caloric requirements and weight loss seen in this patient population. We measured the oxygen cost of augmenting ventilation (O2 cost) using an open circuit technique with dead-space stimulation of ventilation in nine normally nourished (greater than 90% ideal body weight) and in 10 malnourished (less than 90% ideal body weight) patients with COPD as well as in seven normal control subjects. O2 cost was significantly elevated in the malnourished patients with COPD (4.28 +/- 0.98 ml O2/L ventilation) relative to the normally nourished group (2.61 +/- 1.07) and the normal control subjects (1.23 +/- 0.51) (p less than 0.001). The measured resting energy expenditure (REEmeas) was also increased compared with predicted values (REEpred) in the malnourished population (REEmeas/REEpred = 94.57 +/- 6.21% for control subjects, 105.5 +/- 19.66% for normally nourished patients with COPD, and 119.4 +/- 11.69% for malnourished patients with COPD) (p less than 0.005). The malnourished population was characterized by a greater degree of hyperinflation (RV/TLC = 0.55 +/- 0.09 for normally nourished versus 0.69 +/- 0.06 for malnourished patients) and inspiratory muscle weakness (PImax = 51 +/- 16.5 for the normally nourished and 34 +/- 12.2 for the malnourished population). We conclude that malnourished patients with COPD are characterized by a relative increase in resting energy requirements and, specifically, increased energy requirements for augmenting ventilation. This increase in energy requirements may result from the increased mechanical work load associated with severe COPD and/or a reduced ventilatory muscle efficiency.
重度慢性阻塞性肺疾病（COPD）患者常出现体重减轻。呼吸时能量消耗增加可能解释了该患者群体中热量需求增加和体重减轻的现象。我们采用开路技术，通过对通气死腔进行刺激，测量了9名营养正常（大于理想体重的90%）、10名营养不良（小于理想体重的90%）的COPD患者以及7名正常对照者增加通气时的氧耗（O2成本）。与营养正常组（2.61±1.07）和正常对照者（1.23±0.51）相比，营养不良的COPD患者的O2成本显著升高（4.28±0.98 ml O2/L通气）（p<0.001）。与预测值（REEpred）相比，营养不良人群的实测静息能量消耗（REEmeas）也有所增加（对照组REEmeas/REEpred = 94.57±6.21%，营养正常的COPD患者为105.5±19.66%，营养不良的COPD患者为119.4±11.69%）（p<0.005）。营养不良人群的特点是肺过度充气程度更高（营养正常者RV/TLC = 0.55±0.09，营养不良患者为0.69±0.06）和吸气肌无力（营养正常者PImax = 51±16.5，营养不良人群为34±12.2）。我们得出结论，营养不良的COPD患者的特点是静息能量需求相对增加，尤其是增加通气的能量需求。能量需求的增加可能是由于重度COPD相关的机械工作负荷增加和/或通气肌肉效率降低所致。
