Dynamics of noninvasively estimated microvascular O2 extraction during ramp exercise
Dynamics of noninvasively estimated microvascular O2 extraction during ramp exercise
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DOI：
10.1152/japplphysiol.01414.2006
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发表时间：
2007-12-01
影响因子：
3.3
通讯作者：
Barstow, Thomas J.
中科院分区：
文献类型：
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作者：
Ferreira, Leonardo F.;Koga, Shunsaku;Barstow, Thomas J.
斜坡运动期间无创估计微血管 O-2 提取的动态。 J Appl Physiol 103：1999-2004，2007 年。首次发表于 2007 年 9 月 6 日； doi: 10.1152/ japplphyol.01414.2006.-在临床运动测试中利用近红外光谱 (NIRS) 来检测微血管异常需要描述健康个体的反应特征和数据解释的理论基础。我们检查了斜坡运动期间来自 NIRS 的脱氧血红蛋白信号{脱氧血红蛋白 + 肌红蛋白 [脱氧-(Hb + Mb)] 近似于 O2 提取}，以检验估计 O-2 提取的增加接近双曲线的假设，反映肌肉血流量 (Q(m)) 和肌肉摄氧量 (Vo(2m)) 之间具有正 Q(m) 截距的线性关系。 15 名受试者（年龄 24 +/- 5 岁）进行增量斜坡运动至疲劳（15-35 W/min）。通过 NIRS 测量的脱氧 (Hb + Mb) 响应通过双曲函数 [f(x) = ax/(b + x)，其中 a 是渐近值，b 是产生总振幅 50% 的 x 值] 和 S 形函数 {f(x) = f(0) + A/[1 + e (-(-c+dx))] 进行拟合，其中 f(0) 是基线，A 是总振幅振幅，c 是依赖于 d（S 型函数的斜率）的常数}，拟合优度由 F 检验确定。只有一名受试者表现出脱氧 -(Hb + Mb) 的双曲线增加 (a = 170%，b = 193 W)，而 14 名受试者表现出脱氧 -(Hb + Mb) 的 S 形增加（f(0) = -7 +/- 7%、A = 118 +/- 16%、c = 3.25 +/- 1.14 和 d = 0.03 +/- 0.01）。计算机模拟显示，脱氧 (Hb + Mb) 的 S 形增加反映了增量斜坡运动期间微血管 Q(m) 和 Vo(2m) 之间的非线性关系。我们的研究结果的机制意义在于，在大多数健康受试者中，Q(m) 在运动测试早期以比 Vo(2m) 更快的速度增加，并随着接近最大工作率而逐渐减慢。
Dynamics of noninvasively estimated microvascular O-2 extraction during ramp exercise. J Appl Physiol 103: 1999-2004, 2007. First published September 6, 2007; doi: 10.1152/ japplphysiol.01414.2006.-Utilization of near-infrared spectroscopy (NIRS) in clinical exercise testing to detect microvascular abnormalities requires characterization of the responses in healthy individuals and theoretical foundation for data interpretation. We examined the profile of the deoxygenated hemoglobin signal from NIRS {deoxygenated hemoglobin + myoglobin [deoxy-(Hb + Mb)] approximate to O2 extraction} during ramp exercise to test the hypothesis that the increase in estimated O-2 extraction would be close to hyperbolic, reflecting a linear relationship between muscle blood flow (Q(m)) and muscle oxygen uptake (Vo(2m)) with a positive Q(m) intercept. Fifteen subjects (age 24 +/- 5 yr) performed incremental ramp exercise to fatigue (15-35 W/min). The deoxy-(Hb + Mb) response, measured by NIRS, was fitted by a hyperbolic function [f(x) = ax/(b + x), where a is the asymptotic value and b is the x value that yields 50% of the total amplitude] and sigmoidal function {f(x) = f(0) + A/[1 + e (-(-c+dx))], where f(0) is baseline, A is total amplitude, and c is a constant dependent on d, the slope of the sigmoid}, and the goodness of fit was determined by F test. Only one subject demonstrated a hyperbolic increase in deoxy-(Hb + Mb) (a = 170%, b = 193 W), whereas 14 subjects displayed a sigmoidal increase in deoxy-(Hb + Mb) (f(0) = -7 +/- 7%, A = 118 +/- 16%, c = 3.25 +/- 1.14, and d = 0.03 +/- 0.01). Computer simulations revealed that sigmoidal increases in deoxy-(Hb + Mb) reflect a nonlinear relationship between microvascular Q(m) and Vo(2m) during incremental ramp exercise. The mechanistic implications of our findings are that, in most healthy subjects, Q(m) increased at a faster rate than Vo(2m) early in the exercise test and slowed progressively as maximal work rate was approached.