Mancini D M, Ferraro N, Nazzaro D, Chance B, Wilson J R
Department of Medicine, University of Pennsylvania, Philadelphia.
J Am Coll Cardiol. 1991 Aug;18(2):492-8. doi: 10.1016/0735-1097(91)90605-9.
Exertional dyspnea in patients with heart failure may be due, in part, to respiratory muscle underperfusion. Near-infrared spectroscopy is a new technique that permits noninvasive assessment of skeletal muscle oxygenation by monitoring changes in near-infrared light absorption. With use of near-infrared spectroscopy, serratus anterior muscle oxygenation during maximal bicycle exercise was compared in 10 patients with heart failure (ejection fraction 16 +/- 5%) and 7 age-matched normal subjects. Oxygen consumption (VO2), minute ventilation (VE) and arterial saturation were also measured. Changes in difference in absorption between 760 and 800 nm, expressed in arbitrary units, were used to detect muscle deoxygenation. Minimal change in this difference in absorption occurred in normal subjects during exercise, whereas patients with heart failure exhibited progressive changes throughout exercise consistent with respiratory muscle deoxygenation (peak exercise: normal 3 +/- 6, heart failure 12 +/- 4 near-infrared arbitrary units, p less than 0.001). At comparable work loads patients with heart failure had significantly greater minute ventilation and respiratory rate but similar tidal volume when contrasted with normal subjects. However, at peak exercise normal subjects achieved significantly greater minute ventilation and tidal volume with a comparable respiratory rate. No significant arterial desaturation occurred during exercise in either group. These findings indicate that respiratory muscle deoxygenation occurs in patients with heart failure during exercise. This deoxygenation may contribute to the exertional dyspnea experienced by such patients.
心力衰竭患者的运动性呼吸困难可能部分归因于呼吸肌灌注不足。近红外光谱技术是一种通过监测近红外光吸收变化来无创评估骨骼肌氧合的新技术。利用近红外光谱技术，对10例心力衰竭患者（射血分数为16±5%）和7例年龄匹配的正常受试者在最大量自行车运动时的前锯肌氧合情况进行了比较。同时还测量了耗氧量（VO2）、分钟通气量（VE）和动脉血氧饱和度。用760至800纳米之间吸收差异的变化（以任意单位表示）来检测肌肉脱氧情况。正常受试者在运动过程中该吸收差异变化极小，而心力衰竭患者在整个运动过程中呈现出与呼吸肌脱氧一致的渐进性变化（运动峰值时：正常受试者为3±6，心力衰竭患者为12±4个近红外任意单位，p<0.001）。与正常受试者相比，在相当的工作负荷下，心力衰竭患者的分钟通气量和呼吸频率明显更高，但潮气量相似。然而，在运动峰值时，正常受试者在呼吸频率相当的情况下，分钟通气量和潮气量明显更大。两组在运动过程中均未出现明显的动脉血氧饱和度下降。这些发现表明，心力衰竭患者在运动过程中会出现呼吸肌脱氧。这种脱氧可能导致此类患者出现运动性呼吸困难。
