Chen Jennifer, Martin Claudio, McIntyre Christopher W, Ball Ian M, Duffin James, Slessarev Marat
Departments of Medical Biophysics, Western University, London, ON, Canada.
Departments of Medicine, Western University, London, ON, Canada.
Front Med (Lausanne). 2019 Aug 20;6:186. doi: 10.3389/fmed.2019.00186. eCollection 2019.
Passive in-bed cycling (PC) can provide the benefits of early mobilization to critically ill patients who are unable to exercise actively. However, the effect of PC on global hemodynamics and perfusion of ischemia-prone organs, such as the brain and the heart, is unknown. Therefore, prior to studying the effects of PC in hemodynamically fragile critically ill patients, we characterized hemodynamic, brain blood flow, and cardiac function responses to a graded increase in PC cadence in a cohort of healthy subjects. We measured global hemodynamic indices, middle cerebral artery velocity (MCAv), and cardiac function in response to a graded increase in PC cadence. Using 5 min stages, we increased cadence from 5 to 55 RPM in increments of 10 RPM, preceded and followed by 5 min baseline and recovery periods at 0 RPM. The mean values obtained during the last 2 min of each stage were compared within and between subjects for all metrics using repeated measures ANOVA. 11 healthy subjects (6 females) completed the protocol. Between subjects, there was no change in MCAv, cardiac function or hemodynamics with the graded increase in cadence with one exception. There was a 7% increase in mean arterial pressure (MAP) from baseline to 55RPM, that persisted through the recovery period. Across subjects, responses were heterogeneous, with some experiencing reduction in cardiac index, cerebral blood flow (CBF) and cardiac function, especially at higher cadence. In healthy adults, increasing PC cadence increased MAP in all subjects, while cardiac index, CBF, and cardiac function responses varied between subjects. Application of PC to critically ill patients must therefore consider individual variation in responses and tailor the PC to the patient. It is essential to further characterize these responses to PC in the critically ill prior to wide-scale clinical implementation.
被动床上蹬车运动（PC）可为无法主动锻炼的重症患者带来早期活动的益处。然而，PC对全身血流动力学以及易发生缺血的器官（如脑和心脏）灌注的影响尚不清楚。因此，在研究PC对血流动力学不稳定的重症患者的影响之前，我们在一组健康受试者中，对PC踏频分级增加时的血流动力学、脑血流量和心脏功能反应进行了特征描述。我们测量了全身血流动力学指标、大脑中动脉流速（MCAv）以及对PC踏频分级增加的心脏功能反应。以5分钟为一个阶段，我们将踏频从5转/分钟增加到55转/分钟，每次增加10转/分钟，在0转/分钟的基线期和恢复期前后各有5分钟。使用重复测量方差分析，比较了所有指标在每个阶段最后2分钟内受试者内部和受试者之间获得的平均值。11名健康受试者（6名女性）完成了该方案。在受试者之间，除了一个例外，随着踏频分级增加，MCAv、心脏功能或血流动力学没有变化。平均动脉压（MAP）从基线到55转/分钟增加了7%，并持续到恢复期。在所有受试者中，反应是异质性的，一些受试者的心脏指数、脑血流量（CBF）和心脏功能下降，尤其是在较高踏频时。在健康成年人中，增加PC踏频会使所有受试者的MAP升高，而心脏指数、CBF和心脏功能反应在受试者之间存在差异。因此，将PC应用于重症患者时必须考虑个体反应差异，并根据患者情况调整PC。在大规模临床应用之前，进一步明确重症患者对PC的这些反应至关重要。
