Table_1_Cardiopulmonary Capacity in Children During Exercise Testing: The Differences Between Treadmill and Upright and Supine Cycle Ergometry.docx

Background/Hypothesis: Cardiopulmonary exercise testing (CPET) is used in the assessment of function and prognosis of cardiopulmonary health in children with cardiac and pulmonary diseases. Techniques, such as cardiac MRi, and PET-scan, can be performed simultaneously with exercise testing. Thus, it is desirable to have a broader knowledge about children’s normal cardiopulmonary function in different body postures and exercise modalities. The aim of this study was to investigate the effect of different body positions on cardiopulmonary function in healthy subjects performing CPETs.
Materials and Methods: Thirty-one healthy children aged 9, 12, and 15 years did four CPETs: one treadmill test with a modified Bruce protocol and three different bicycle tests with different body postures, sitting, tilted 45°, and lying flat (0°). For the bicycle tests, a 20-watt ramp protocol with a pedal frequency of 60 ± 5 rotations per minute was used. Continous ECG and breath-by-breath V.O2 measurements was done throughout the tests. Cardiac structure and function including aortic diameter were evaluated by transthoracic echocardiography prior to the tests. Doppler measurements of the blood velocity in the ascending aorta were measured prior to and during the test. Prior to every test, the participants performed pulmonary function tests with maximum voluntary ventilation test.
Results: There is a significantly (p < 0.05) lower peak V.O2 in all bicycle tests compared with the treadmill test. There is lower corrected peak V.O2 (ml kg−0.67 min−1), but not relative peak V.O2 (ml kg−1 min−1), in the supine compared with the upright bicycle test. There are no differences in peak stroke volume or cardiac output between the bicycle modalities when calculated from aortic blood flow. Peak heart rate decreases from both treadmill to upright bicycle and from upright bicycle to the supine test (0°).
Conclusion: There are no differences in peak cardiac output between the upright bicycle test and supine bicycle tests. Heart rate and corrected peak V.O2 are lower in the supine test (0°) than the upright bicycle test. In the treadmill test, it is a higher absolute and relative peak V.O2. Despite the latter differences, we are convinced that both upright and supine bicycle tests are apt in the clinical setting when needed.

背景/假说：心肺运动试验（Cardiopulmonary Exercise Testing, CPET）目前被用于评估儿童心肺疾病患者的心肺功能状态与预后情况。诸如心脏磁共振成像（cardiac MRI）、PET扫描（PET-scan）等技术，可与运动试验同步开展。因此，亟需全面掌握不同体位与运动模式下健康儿童的正常心肺功能特征。本研究旨在探究不同身体体位对完成心肺运动试验的健康受试者心肺功能的影响。

材料与方法：本研究纳入31名年龄分别为9、12、15岁的健康儿童，共完成4次心肺运动试验：1次采用改良Bruce方案的跑台试验，以及3种不同身体体位的自行车试验，分别为坐姿、倾斜45°卧位与平卧位（0°）。自行车试验采用20瓦递增负荷方案，踏板频率维持在60±5转/分钟。试验全程同步记录心电图（ECG）并采用逐次呼吸法测定摄氧量（V.O₂）。试验前通过经胸超声心动图（transthoracic echocardiography）评估受试者心脏结构与功能，包括主动脉直径；并在试验前及试验过程中，采用多普勒技术测量升主动脉内的血流速度。每次试验前，受试者均需完成最大自主通气量（maximum voluntary ventilation）肺功能测试。

结果：所有自行车试验的峰值摄氧量均显著低于跑台试验（p<0.05）。与直立位自行车试验相比，平卧位自行车试验的校正后峰值摄氧量（ml·kg⁻⁰·⁶⁷·min⁻¹）更低，但相对峰值摄氧量（ml·kg⁻¹·min⁻¹）无显著差异。根据主动脉血流计算所得的每搏峰值量与心输出量，在不同体位的自行车试验之间无显著差异。峰值心率从跑台试验到直立位自行车试验，再到平卧位试验（0°）均呈下降趋势。

结论：直立位与平卧位自行车试验的峰值心输出量无显著差异。平卧位试验（0°）的峰值心率与校正后峰值摄氧量均低于直立位自行车试验。跑台试验的绝对与相对峰值摄氧量均更高。尽管存在上述差异，我们仍认为在临床有需求时，直立位与平卧位自行车试验均适用于临床场景。