Although the administration of fluid is the first treatment considered in almost all cases of circulatory failure, this therapeutic option poses two essential problems: the increase in cardiac output induced by a bolus of fluid is inconstant, and the deleterious effects of fluid overload are now clearly demonstrated. This is why many tests and indices have been developed to detect preload dependence and predict fluid responsiveness. In this review, we take stock of the data published in the field over the past three years. Regarding the passive leg raising test, we detail the different stroke volume surrogates that have recently been described to measure its effects using minimally invasive and easily accessible methods. We review the limits of the test, especially in patients with intra-abdominal hypertension. Regarding the end-expiratory occlusion test, we also present recent investigations that have sought to measure its effects without an invasive measurement of cardiac output. Although the limits of interpretation of the respiratory variation of pulse pressure and of the diameter of the vena cava during mechanical ventilation are now well known, several recent studies have shown how changes in pulse pressure variation itself during other tests reflect simultaneous changes in cardiac output, allowing these tests to be carried out without its direct measurement. This is particularly the case during the tidal volume challenge, a relatively recent test whose reliability is increasingly well established. The mini-fluid challenge has the advantage of being easy to perform, but it requires direct measurement of cardiac output, like the classic fluid challenge. Initially described with echocardiography, recent studies have investigated other means of judging its effects. We highlight the problem of their precision, which is necessary to evidence small changes in cardiac output. Finally, we point out other tests that have appeared more recently, such as the Trendelenburg manoeuvre, a potentially interesting alternative for patients in the prone position.

尽管输液是几乎所有循环衰竭病例中考虑的第一种治疗方法，但这种治疗选择存在两个基本问题：由输液引起的心输出量增加是不稳定的，并且液体超负荷的有害影响现在很明显证明了。这就是为什么开发了许多测试和指标来检测前负荷依赖性和预测液体反应性的原因。在这篇综述中，我们盘点了过去三年在该领域发表的数据。关于被动抬腿测试，我们详细介绍了最近描述的不同每搏输出量替代物，以使用微创且易于访问的方法测量其效果。我们回顾了测试的局限性，特别是在腹内高压患者中。关于呼气末阻塞测试，我们还介绍了最近的研究，这些研究试图在没有侵入性测量心输出量的情况下测量其效果。尽管在机械通气期间对脉压的呼吸变化和腔静脉直径的解释的局限性现已众所周知，但最近的几项研究表明，在其他测试期间脉压变化本身的变化如何反映心输出量的同时变化，允许在没有直接测量的情况下进行这些测试。在潮气量挑战期间尤其如此，这是一项相对较新的测试，其可靠性日益得到确立。微量流体挑战具有易于执行的优点，但它需要直接测量心输出量，就像经典的流体挑战一样。最初用超声心动图描述，最近的研究调查了其他判断其效果的方法。我们强调了它们的精度问题，这对于证明心输出量的微小变化是必要的。最后，我们指出最近出现的其他测试，例如特伦德伦堡动作，对于俯卧位的患者来说，这是一种可能有趣的替代方法。