Belardinelli R, Georgiou D, Barstow T J
Department of Medicine, Harbor-UCLA Medical Center, Torrance, USA.
G Ital Cardiol. 1995 Jun;25(6):715-24.
Near infrared spectroscopy (NIRS) is a noninvasive technique of monitoring tissue oxygen saturation by detecting changes in tissue absorbance of two wavelengths (850 and 760 nm) reflecting the relative oxygenation of hemoglobin and myoglobin. Aim of the present study was to determine whether changes in skeletal muscle oxygen saturation during incremental exercise detected by NIRS can reflect an impared oxygen delivery and an early onset of anaerobic metabolism in patients with chronic heart failure (CHF). We studied 19 subjects (mean age 43 +/- 16 years). Seven patients had a history of CHF with a diagnosis of ischemic cardiomyopathy (Group A) and 12 were healthy sedentary (Group B). All patients had a history of dyspnea on exertion (NY-HA II), peripheral edema, pulmonary rales and cardiac gallop sounds over the last 6 months. They were in sinus rhythm and stable clinical condition in the last 3 months. They were well matched regarding age, sex and body surface area. All subjects performed an incremental work rate test in a ramp pattern on a upright cycle ergometer until volitional fatigue. Gas exchange was measured breath by breath with a metabolic chart. Muscle oxygenation was determined, transcutaneously, during the exercise test over the vastus lateralis muscle with NIRS. At peak exercise, work rate, VO2, anaerobic threshold (LAT), heart rate and systolic blood pressure were significantly lower in Group A compared to Group B (92 +/- 28 vs 232 +/- 17 watts; 14 +/- 2 vs 21 +/- 2 ml/kg/min; 868 +/- 225 vs 1317 +/- 354 ml/min; 149 +/- 7 vs 172 +/- 18 b/min; 145 +/- 18 vs 195 +/- 21 mm Hg, respectively; p < 0.0001 for all). In both groups, as work rate increased, tissue oxygenation initially either remained constant near resting levels or decreased. In both groups, muscle oxygenation decreased more steeply near the work rate where lactic acidosis (LAT) was detected. However, patients with CHF had an earlier acceleration in muscle deoxygenation compared to the other group, indicating a premature onset of anaerobic metabolism. Moreover, Group A had a flatter increase in both heart rate and systolic blood pressure and a steeper slope of oxygenation profile at all matched workloads compared to normals (Group A: -0.13 +/- 0.03 ml/min; Group B: -0.06 +/- 0.015 ml/min; p < 0.0001). The LAT correlated with the work rate at which the rate of tissue O2 desaturation accelerated (r = 0.94; p < 0.0001).(ABSTRACT TRUNCATED AT 400 WORDS)
近红外光谱（NIRS）是一种通过检测反映血红蛋白和肌红蛋白相对氧合作用的两个波长（850和760纳米）的组织吸光度变化来监测组织氧饱和度的非侵入性技术。本研究的目的是确定通过NIRS检测到的递增运动期间骨骼肌氧饱和度的变化是否能反映慢性心力衰竭（CHF）患者氧输送受损和无氧代谢的早期发生。我们研究了19名受试者（平均年龄43±16岁）。7例有CHF病史，诊断为缺血性心肌病（A组），12例为健康久坐者（B组）。所有患者在过去6个月内均有劳力性呼吸困难（NY-HA II级）、外周水肿、肺部啰音和心音奔马律。他们在过去3个月内心律为窦性，临床状况稳定。他们在年龄、性别和体表面积方面匹配良好。所有受试者在直立式自行车测力计上以斜坡模式进行递增工作率测试，直至自愿疲劳。用代谢图表逐次测量气体交换。在运动测试期间，用NIRS经皮测定股外侧肌的肌肉氧合。在运动峰值时，A组的工作率、VO2、无氧阈值（LAT）、心率和收缩压均显著低于B组（分别为92±28 vs 232±17瓦；14±2 vs 21±2毫升/千克/分钟；868±225 vs 1317±354毫升/分钟；149±7 vs 172±18次/分钟；145±18 vs 195±21毫米汞柱；所有p<0.0001）。在两组中，随着工作率增加，组织氧合最初要么在静息水平附近保持恒定，要么下降。在两组中，在检测到乳酸酸中毒（LAT）的工作率附近，肌肉氧合下降得更陡峭。然而，与另一组相比，CHF患者的肌肉脱氧加速更早，表明无氧代谢过早发生。此外，与正常人相比，A组在所有匹配工作量下心率和收缩压的增加更平缓，氧合曲线的斜率更陡（A组：-0.13±0.03毫升/分钟；B组：-0.06±0.015毫升/分钟；p<0.0001）。LAT与组织O2去饱和速率加速时的工作率相关（r=0.94；p<0.0001）。（摘要截断于400字）
