Department of Intensive Care Medicine, St George's Healthcare NHS Trust and St George's University of London, Tooting, London SW17 0QT, UK.
Servicio de Cuidados Intensivos, Hospital SAS de Jerez, C/Circunvalación s/n, 11407 Jerez de la Frontera, Spain.
Br J Anaesth. 2017 Jun 1;118(6):938-946. doi: 10.1093/bja/aex070.
BACKGROUND.: Dynamic arterial elastance (Ea dyn ), the relationship between pulse pressure variation (PPV) and stroke volume variation (SVV), has been suggested as a functional assessment of arterial load. The aim of this study was to evaluate the impact of arterial load changes during acute pharmacological changes, fluid administration, and haemorrhage on Ea dyn .
METHODS.: Eighteen anaesthetized, mechanically ventilated New Zealand rabbits were studied. Arterial load changes were induced by phenylephrine ( n =9) or nitroprusside ( n =9). Thereafter, animals received a fluid bolus (10 ml kg -1 ), followed by stepwise bleeding (blood loss: 15 ml kg -1 ). The influence of arterial load and cardiac variables on PPV, SVV, and Ea dyn was analysed using a linear mixed-effects model analysis.
RESULTS.: After phenylephrine infusion, mean ( sd ) Ea dyn decreased from 0.89 (0.14) to 0.49 (0.12), P <0.001; whereas after administration of nitroprusside, Ea dyn increased from 0.80 (0.23) to 1.28 (0.21), P <0.0001. Overall, the fluid bolus decreased Ea dyn [from 0.89 (0.44) to 0.73 (0.35); P <0.01], and haemorrhage increased it [from 0.78 (0.23) to 0.95 (0.26), P =0.03]. Both PPV and SVV were associated with similar arterial factors (effective arterial elastance, arterial compliance, and resistance) and heart rate. Furthermore, PPV was also related to the acceleration and peak velocity of aortic blood flow. Both arterial and cardiac factors contributed to the evolution of Ea dyn throughout the experiment.
CONCLUSIONS.: Acute modifications of arterial load induced significant changes on Ea dyn ; vasodilatation increased Ea dyn , whereas vasoconstriction decreased it. The Ea dyn was associated with both arterial load and cardiac factors, suggesting that Ea dyn should be more properly considered as a ventriculo-arterial coupling index.
动态动脉弹性（Ea dyn ），即脉压变化（PPV）与每搏量变化（SVV）之间的关系，已被认为是对动脉负荷的一种功能评估。本研究旨在评估急性药理学变化、液体输注和出血期间动脉负荷变化对 Ea dyn 的影响。
研究了 18 只麻醉、机械通气的新西兰兔。通过苯肾上腺素（n = 9）或硝普钠（n = 9）诱导动脉负荷变化。此后，动物接受 10ml/kg 的液体冲击，随后逐步失血（失血 15ml/kg）。使用线性混合效应模型分析评估动脉负荷和心脏变量对 PPV、SVV 和 Ea dyn 的影响。
苯肾上腺素输注后，平均（标准差）Ea dyn 从 0.89（0.14）降至 0.49（0.12），P <0.001；而给予硝普钠后，Ea dyn 从 0.80（0.23）增加至 1.28（0.21），P <0.0001。总体而言，液体冲击降低了 Ea dyn [从 0.89（0.44）降至 0.73（0.35），P <0.01]，出血增加了 Ea dyn [从 0.78（0.23）增至 0.95（0.26），P =0.03]。PPV 和 SVV 均与相似的动脉因素（有效动脉弹性、动脉顺应性和阻力）和心率相关。此外，PPV 还与主动脉血流加速和峰值速度相关。动脉和心脏因素均有助于整个实验中 Ea dyn 的演变。
急性动脉负荷变化导致 Ea dyn 发生显著变化；血管扩张增加 Ea dyn ，而血管收缩降低 Ea dyn 。Ea dyn 与动脉负荷和心脏因素均相关，提示 Ea dyn 应更恰当地被视为心室-动脉耦联指数。
