Meyer K, Hajric R, Westbrook S, Samek L, Lehmann M, Schwaibold M, Betz P, Roskamm H
Herz-Zentrum, Bad Krozingen, Germany.
Eur J Appl Physiol Occup Physiol. 1996;72(5-6):387-93. doi: 10.1007/BF00242266.
In healthy normal individuals (n = 69), coronary patients with myocardial ischaemia (n = 27) and patients with chronic heart failure (CHF, n = 33), four widely applied methods to determine ventilatory threshold (VT) were analysed: V-slope, ventilatory equivalent for O2 (EqO2), gas exchange ratio (R) and end-tidal partial pressure of oxygen. Lactate threshold [LAT, log lactate vs log oxygen uptake (VO2)] was also determined. Analysis focused on rate of success of threshold determination, comparability of threshold methods, reproducibility and interobserver variability. Cycle ergometry protocols with ramp-like mode and graded steady-state mode used in exercise testing were considered separately. In healthy normal individuals and coronary patients with myocardial ischaemia, at least three VT could be determined during ramp-like mode and two VT during graded steady-state mode, 82% of the time. For CHF patients, the rate of successful determination of VT was lower. Compared to LAT, VO2 at VT was significantly higher using R and EqO2 methods of VT determination in healthy normal subjects (P < 0.01), and significantly higher when using all four methods in coronary patients (P < 0.01 or P < 0.05, respectively). No difference was observed between VO2 at VT and LAT in CHF patients. In healthy normal individuals, day-to-day reproducibility of VT and LAT was high (error of a single determination from duplicate determinations was between 3.9% and 6.2% corresponding to a VO2 of 52.2 and 89.2 ml.min-1). Interobserver variability was low (error between 0.3% and 5% corresponding to a VO2 of 9.8 and 68 ml.min-1). In CHF patients, interobserver variability was moderately greater (error between 4.6% and 8.2%, corresponding to a VO2 of 35.1 and 62.4 ml.min-1). To optimize threshold determination, standardized procedures are suggested.
在健康正常个体（n = 69）、患有心肌缺血的冠心病患者（n = 27）和慢性心力衰竭（CHF，n = 33）患者中，分析了四种广泛应用的确定通气阈值（VT）的方法：V斜率、氧通气当量（EqO2）、气体交换率（R）和呼气末氧分压。还测定了乳酸阈值[LAT，乳酸对数与摄氧量（VO2）对数]。分析重点在于阈值确定的成功率、阈值方法的可比性、可重复性和观察者间变异性。运动测试中使用的具有斜坡样模式和分级稳态模式的周期测力计方案分别进行了考虑。在健康正常个体和患有心肌缺血的冠心病患者中，在斜坡样模式下至少可在82%的时间内确定三个VT，在分级稳态模式下可确定两个VT。对于CHF患者，VT的成功确定率较低。与LAT相比，在健康正常受试者中使用R和EqO2方法确定VT时，VT时的VO2显著更高（P < 0.01），在冠心病患者中使用所有四种方法时VO2也显著更高（分别为P < 0.01或P < 0.05）。在CHF患者中，VT时的VO2与LAT之间未观察到差异。在健康正常个体中，VT和LAT的每日可重复性很高（重复测定中单次测定的误差在3.9%至6.2%之间，对应于VO2为52.2和89.2 ml·min-1）。观察者间变异性较低（误差在0.3%至5%之间，对应于VO2为9.8和68 ml·min-1）。在CHF患者中，观察者间变异性略大（误差在4.6%至8.2%之间，对应于VO2为35.1和62.4 ml·min-1）。为优化阈值确定，建议采用标准化程序。
