Abstract
In patients with acute circulatory failure, the decision to give fluids or not should not be taken lightly. The risk of overzealous fluid administration has been clearly established. Moreover, volume expansion does not always increase cardiac output as one expects. Thus, after the very initial phase and/or if fluid losses are not obvious, predicting fluid responsiveness should be the first step of fluid strategy. For this purpose, the central venous pressure as well as other “static” markers of preload has been used for decades, but they are not reliable. Robust evidence suggests that this traditional use should be abandoned. Over the last 15 years, a number of dynamic tests have been developed. These tests are based on the principle of inducing short-term changes in cardiac preload, using heart–lung interactions, the passive leg raise or by the infusion of small volumes of fluid, and to observe the resulting effect on cardiac output. Pulse pressure and stroke volume variations were first developed, but they are reliable only under strict conditions. The variations in vena caval diameters share many limitations of pulse pressure variations. The passive leg-raising test is now supported by solid evidence and is more frequently used. More recently, the end-expiratory occlusion test has been described, which is easily performed in ventilated patients. Unlike the traditional fluid challenge, these dynamic tests do not lead to fluid overload. The dynamic tests are complementary, and clinicians should choose between them based on the status of the patient and the cardiac output monitoring technique. Several methods and tests are currently available to identify preload responsiveness. All have some limitations, but they are frequently complementary. Along with elements indicating the risk of fluid administration, they should help clinicians to take the decision to administer fluids or not in a reasoned way.
Highlights
Volume expansion, the first-line treatment of acute circulatory failure, can be the source of a crucial therapeutic dilemma
The pivotal study by Rivers et al [1] showed that massive fluid administration during the first 6 h of resuscitation of patients with severe sepsis and septic shock was associated with improved outcome
Due to varying shapes that the Frank–Starling curve could take depending on the ventricular systolic function, a fluid challenge could lead to either a significant or a negligible increase in stroke volume and cardiac output (Fig. 1)
Summary
The first-line treatment of acute circulatory failure, can be the source of a crucial therapeutic dilemma. There is a tremendous amount of evidence that a given value of CVP does not predict fluid responsiveness. In a survey regarding haemodynamic monitoring in patients undergoing high-risk surgery, 73% of American and 84% of European anaesthesiologists reported that they used the CVP to guide fluid management [18] This inconsistency is even more difficult to understand since the inability of CVP to reflect preload responsiveness comes from simple physiology. A static value of CVP could correspond to preload responsiveness as well as preload unresponsiveness, depending on the shape of the Frank–Starling curve, which varies from one patient to another and, in a patient, from one time to another (Fig. 1). What is true for the CVP is true for all static indicators of cardiac preload, such as the pulmonary artery occlusion pressure, the global end-diastolic volume measured with transpulmonary thermodilution and the
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
