Moller Per W, Winkler Bernhard, Hurni Samuel, Heinisch Paul Philipp, Bloch Andreas, Sondergaard Soren, Jakob Stephan M, Takala Jukka, Berger David
Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland.
Department of Anaesthesiology and Intensive Care Medicine, Institute of Clinical Sciences at the Sahlgrenska Academy, University of Gothenburg, Sahlgrenska University Hospital, Gothenburg, Sweden.
Am J Physiol Heart Circ Physiol. 2017 Aug 1;313(2):H408-H420. doi: 10.1152/ajpheart.00081.2017. Epub 2017 May 26.
The relevance of right atrial pressure (RAP) as the backpressure for venous return (Q) and mean systemic filling pressure as upstream pressure is controversial during dynamic changes of circulation. To examine the immediate response of Q (sum of caval vein flows) to changes in RAP and pump function, we used a closed-chest, central cannulation, heart bypass porcine preparation ( = 10) with venoarterial extracorporeal membrane oxygenation. Mean systemic filling pressure was determined by clamping extracorporeal membrane oxygenation tubing with open or closed arteriovenous shunt at euvolemia, volume expansion (9.75 ml/kg hydroxyethyl starch), and hypovolemia (bleeding 19.5 ml/kg after volume expansion). The responses of RAP and Q were studied using variable pump speed at constant airway pressure (P) and constant pump speed at variable P Within each volume state, the immediate changes in Q and RAP could be described with a single linear regression, regardless of whether RAP was altered by pump speed or P ( = 0.586-0.984). RAP was inversely proportional to pump speed from zero to maximum flow ( = 0.859-0.999). Changing P caused immediate, transient, directionally opposite changes in RAP and Q (RAP: ≤ 0.002 and Q: ≤ 0.001), where the initial response was proportional to the change in Q driving pressure. Changes in P generated volume shifts into and out of the right atrium, but their effect on upstream pressure was negligible. Our findings support the concept that RAP acts as backpressure to Q and that Guyton's model of circulatory equilibrium qualitatively predicts the dynamic response from changing RAP. Venous return responds immediately to changes in right atrial pressure. Concomitant volume shifts within the systemic circulation due to an imbalance between cardiac output and venous return have negligible effects on mean systemic filling pressure. Guyton's model of circulatory equilibrium can qualitatively predict the resulting changes in dynamic conditions with right atrial pressure as backpressure to venous return.
在循环动态变化过程中，右心房压力（RAP）作为静脉回流（Q）的背压以及平均体循环充盈压作为上游压力的相关性存在争议。为了研究Q（腔静脉血流总和）对RAP和泵功能变化的即时反应，我们使用了一种开胸、中心插管、体外循环猪模型（n = 10），并采用静脉 - 动脉体外膜肺氧合。平均体循环充盈压通过在血容量正常、容量扩张（9.75 ml/kg羟乙基淀粉）和低血容量（容量扩张后失血19.5 ml/kg）状态下，夹闭体外膜肺氧合管道（动静脉分流开放或关闭）来测定。在恒定气道压力（P）下使用可变泵速以及在可变P下使用恒定泵速来研究RAP和Q的反应。在每种容量状态下，Q和RAP的即时变化都可以用单一的线性回归来描述，无论RAP是由泵速还是P改变（r = 0.586 - 0.984）。从零时流量到最大流量，RAP与泵速成反比（r = 0.859 - 0.999）。改变P会导致RAP和Q立即出现短暂的、方向相反的变化（RAP：P ≤ 0.002，Q：P ≤ 0.001），其中初始反应与Q驱动压力的变化成正比。P的变化会导致容量在右心房内外转移，但其对上游压力的影响可忽略不计。我们的研究结果支持以下概念：RAP作为Q的背压，并且盖顿循环平衡模型定性地预测了RAP变化引起的动态反应。静脉回流对右心房压力的变化立即做出反应。由于心输出量与静脉回流之间的不平衡导致的体循环内伴随的容量转移对平均体循环充盈压的影响可忽略不计。盖顿循环平衡模型可以定性地预测以右心房压力作为静脉回流血流背压时动态条件下的相应变化。
