Defining Fluid Responsiveness: A Guide to Patient-Tailored Volume Titration

FLUID RESPONSIVENESS is a strategy used to select patients who will respond with a positive reaction in a physiologic parameter upon fluid administration. Curiously, there is no generally accepted definition of fluid responsiveness. A provisional definition of fluid responsiveness would be "the positive reaction of a physiologic parameter of a certain size to a standardized volume of a certain type of fluid administered within a certain amount of time and measured within a certain interval." It is clear that these issues need to be resolved before a more detailed and precise definition can be proposed. The aim of predicting fluid responsiveness is to achieve this positive reaction while using the least amount of fluids. Accurate prediction of fluid responsiveness to facilitate patient-tailored fluid titration is crucial, as it has been shown that only half of critically ill patients will respond to fluid loading with an increase in cardiac output. 1 Marik P.E. Cavalazzi R. Vasu T. et al. Dynamic changes in arterial waveform derived variables and fluid responsiveness in mechanically ventilated patients: a systematic review of the literature. Crit Care Med. 2009; 37: 2642-2647 Crossref PubMed Scopus (269) Google Scholar , 2 Michard F. Teboul J.L. Predicting fluid responsiveness in ICU patients: a critical analysis of the evidence. Chest. 2002; 121: 2000-2008 Crossref PubMed Scopus (532) Google Scholar Moreover, unnecessary fluid administration has shown to increase morbidity, mortality, and hospital and intensive care stays. 3 Holte K. Kehlet H. Fluid therapy and surgical outcomes in elective surgery: a need for reassessment in fast-track surgery. J Am Coll Surg. 2006; 202: 971-989 Abstract Full Text Full Text PDF PubMed Scopus (94) Google Scholar , 4 Wiedemann H.P. Wheeler A.P. Bernard G.R. et al. Comparison of two fluid-management strategies in acute lung injury. N Engl J Med. 2006; 354: 2564-2575 Crossref PubMed Scopus (1004) Google Scholar , 5 Boyd J.H. Forbes J. Nakada T.A. et al. Fluid resuscitation in septic shock: a positive fluid balance and elevated central venous pressure are associated with increased mortality. Crit Care Med. 2011; 39: 259-265 Crossref PubMed Scopus (163) Google Scholar Over the last decade, the rise in the number of publications about fluid responsiveness in the intensive care and operating room has shown the increased interest in this topic. In this review, the authors describe the physiology, requirements, and limitations of fluid responsiveness. Subsequently, using available literature, a practical definition on fluid responsiveness is proposed. The reliability of clinical, static, and hemodynamic parameters is evaluated to predict the response to fluid loading in critically ill patients. Finally, the potential, shortcomings, and use of passive leg raising are discussed in this review.