研究背景：
心肺运动试验简介：心肺运动试验（cardiopulmonary exercise test，CPET）作为一种定量、客观、精准的人体整体功能学检测技术^[1,2]，与其他传统的单一器官或单一系统功能的检测方法不同，把人真正的看作一个整体，对整个运动负荷过程中人体心肺代谢整体一体化联合调控反应进行全面综合精确的评估，通过对气体交换、心电、血流动力学和负荷功率等指标连续动态变化的综合分析，评价人以心肺为核心的整体功能状态，判断运动受限的原因，心血管疾病的诊断及鉴别诊断，判断疾病严重程度，评估预后预测，特别是整体论指导CPET制定个体化精准运动整体方案，进行心肺代谢等慢病糖脂压有效转归的整体管理等。CPET也被称为症状限制性最大极限运动，临床应用中对CPET进行规范化操作并且做到“最大极限运动”以保证评估结果相关指标特别是峰值摄氧量等核心指标的准确性尤为重要。目前不同学科的运动相关指南对于最大极限运动的定义及停止运动的标准尚未统一，不少以CPET峰值呼吸交换率（RER）、血压及心率达到何值作为参考^[1-5]。若以某峰值呼吸交换率（Peak RER）、某血压或某心率特定值作为终止试验标准，一方面会让部分患者的功能指标等被低估，另一方面会因达不到该特定值而产生危险，因此对CPET最大极限运动质疑时，设计用Max试验进行个体化定量精准的验证^[6,7]。
目的：
临床CPET应用过程中设计Max试验以验证临床受试者所完成的CPET是否为最大极限运动、验证CPET功能评估结果客观定量的准确性和以某指标的特定数值作为停止CPET的标准是否可行及安全。
方法：
从2017年6月到2019年1月，在中国医学科学院阜外医院选择216名受试者，其中正常组41例，病例组175例。签署同意书后，进行CPET和Max测试。本研究分为两个阶段：第一阶段，首先在60名受试者中尝试分析Max试验，探讨初步经验；第二阶段，进一步扩大研究例数156例受试者，进行全面分析。正常组为体检无异常的健康人，病例组其CPET峰值RER≤1.10，或者峰值心率和峰值血压反应弱。Max试验方法：在完成CPET恢复≥5 min后，先蹬车≥60 r/min，再给予该受试者130%峰值功率恒定运动，鼓励运动至不能坚持的极限状态。计算分析Max试验30 s的最大心率和最大摄氧量及其与CPET峰值心率和峰值摄氧量之间的差值和差值百分比。评测标准：（1）若心率和摄氧量任一指标的差值百分比≤-10%（表明Max测试的数值低于CPET峰值数据）则定义Max试验操作失败，否则为成功；（2）若心率和摄氧量的差值百分比均在-10～10%，则Max试验操作成功，证明CPET数据为极限运动，CPET Peak相关数据是较为准确的评估病人状态；（3）若心率和摄氧量差值任一指标差值百分比≥10%时，则Max试验操作成功，证明CPET结果为非极限运动。
结果：
病例组峰值摄氧量（L/min、ml·min^-1·kg^-1）、无氧阈（L/min、ml·min^-1·kg^-1、%pred）、峰值氧脉搏（ml/次、%pred）、Peak RER、峰值收缩压、峰值运动负荷（W/min）、峰值心率（次/min）、摄氧有效性峰值平台（OUEP）（比值、%pred）低于正常组，二氧化碳通气有效性平均90 s最低值（V E/VCO2-lowest）（比值、%pred）、二氧化碳通气效率斜率（V E/V ECO2 slope）（比值、%pred）高于正常组（P<0.05）。所有正常组与病例组均安全无任何事件完成CPET和Max试验。216例受试者中，Max试验成功198例（91.7%），其中证明CPET为极限运动182例，为非极限运动16例；失败18例（8.3%）。Max试验成功例恒定功率运动持续时间（48±13s）显著高于失败例持续时间（27±12s），差异有统计学意义（P<0.05）。Max试验成功例其最大摄氧量（1101.6±528.3 ml/min）较CPET非极限运动例（860.3±386.1 ml/min）大，差异有统计学意义（P<0.05）。Max试验成功例其最大心率（132±27次/min）较CPET非极限运动例（113±24次/min）高，差异有统计学意义（P<0.05）。
结论：
对于峰值RER低、运动中血压和心率无反应而被质疑的症状限制性最大极限CPET，在恢复5 min后再完成Max试验可以证实CPET客观定量评估结果的准确性。Max试验配合完善CPET方法安全可行，值得进一步深入研究和临床推广应用。

background:
introduction to cardiopulmonary exercise test: cardiopulmonary exercise test (cpet) is an ive, quantitative and accurate method for the detection of human body function. that considered people as a whole to comprehensively and accurately assess the human heart and lung during exercise load. comprehensive analysis of continuous dynamic changes such as gas exchange, cardiac electrophysiology, hemodynamics, and load power, that can evaluate the overall reserve function, and judges the cause of exercise limitation. diagnosis, differential diagnosis of vascular diseases, judgment of disease severity, assessment of prognosis and development of cardiopulmonary disease rehabilitation programs. cpet is also known as the symptom-limited maximum cpet. standardized operations are especially important. at present, the standards of the various disciplines for the respiratory exchange rate (rer), blood pressure and heart rate in cpet have not been unified as the criteria for stopping the exercise. if a certain peak respiratory exchange rate (peak rer), a certain blood pressure or a specific heart rate is used as the termination test standard, on the one hand, the functional indicators of some patients may be underestimated, and on the other hand, the patients will be dangerous.
ive:
the max test(max)is designed during clinical cpet application to verify whether the cpet performed by the clinical subject is the maximum extreme exercise, to verify the accuracy of the quantitative cpet evaluation result, and whether it is feasible and safe to use the specific value of a certain index as the standard for stopping cpet.
methods:
216 cases from fuwai hospital were selected during june 2017 to january 2019, including 41 healthy person(control group) and 175 with cardiovascular diseases (patient group). after signed the consent form, the cpet and max were performed. the max was first attempted in 60 subjects, and then 156 subjects were further expanded. the normal group was a healthy person. the patients had a cpet peak rer ≤ 1.10, or the peak heart rate and peak blood pressure were basically non-responsive. when the cpet ended, they had a 5-minute break, then the max, during which, they cycled with a velocity of ≥ 60 r/min, at a constant intensity equivalent to 130% of peak work, until exhausted. the difference and percentage difference between the peak heart rate and the peak oxygen uptake were calculated. (1)if the percentage difference of heart rate and oxygen uptake are all less than -10%, then the max is defined as failure, otherwise it is successful. (2)if the percentage difference is between -10~10%, then the max is successful, which proved that the cpet is precise. (3)if the difference is ≥10%, the max is successful, which proves that the cpet is non-extreme exercise.
results:
patient group’s peak v o2(l/min，ml·min^-1·kg^-1), anaerobic threshold(l/min,ml·min^-1·kg^-1,%pred), peak o2p (ml/time,% pred),peak rer, peak sbp, peak wr, peak heart rate, ouep(ratio,%pred)were lower than those of the control group(p<0.05).the ve/ vco2 slope (ratio,%pred)and lowest ve/ vco2(ratio,%pred) were higher in the patient group than in the control group (p<0.05).no adverse events occurred during the cpet and max in all cases. among the 216 cases, max was successful in 198 cases(91.7%). cpet was proved to be maximum extreme exercise for 182 cases, non-maximum extreme exercise for 16 cases, and failed in 18 cases(8.3%). the duration of constant power exercise (48±13 s) in the successful max was higher than that in the failure case (27±12 s), and the difference was statistically significant (p<0.05). in the max cases, the maximum oxygen uptake (1101.6±528.3 ml/min) was larger than that of the cpet non-extreme exercise (860.3±386.1 ml/min), and the difference was statistically significant (p<0.05). the maximal heart rate (132±27 beats/min) was higher in the max cases than in the cpet non-extreme exercise (113±24 beats/min), and the difference was statistically significant (p<0.05).
conclusion :
for cpet with a low peak rer and a maximum challenge，the max can be completed after recovery 5 minutes to confirm the accuracy of the ive quantitative assessment of cpet. max is safe and feasible, and that deserved further research and clinical application.