Evaluation of fluid responsiveness in ventilated septic patients: back to venous return
Adequate tissue perfusion and oxygen delivery is the primary goal of the therapeutic management of patientswith circulatory failure. Cardiac output—a major determinant of oxygen delivery—is the result of the interaction between the cardiac pump and venous return. Since cardiac output must equal the volume of blood entering the heart, an increase in venous return will increase cardiac output, provided that the venous return curve intersects with the ascending limb of the cardiac function curve . This defines the preload dependence of the heart. In contrast, a further increase in preload when the heart operates on the flat portion of its function curve fails to increase cardiac output and results in increased filling pressure with potential deleterious venous congestion. Importantly, there is no fluid responsiveness of the left ventricle (LV) without right ventricular (RV) preload dependence . A pivotal clinical question frequently raised is, therefore, the evaluation of RV ability to increase its output significantly in response to a fluid challenge. Another clinical question even more challenging to address is to determine if the patient really needs a higher cardiac output to improve his current condition.
KeywordsRight Ventricular Inferior Vena Cava Venous Return Fluid Responsiveness Stroke Volume Variation
Unable to display preview. Download preview PDF.
- 1.Magder S (1993) Shock physiology. In: Pinsky MR, Dhainault JF (eds) Physiological foundations of critical care medicine. Williams and Wilkins, Philadelphia, pp 140–160Google Scholar
- 6.Mitaka C, Nagura T, Sakanishi N, Tsunoda Y, Amaha K (1989) Two-dimensional echocardiographic evaluation of inferior vena cava, right ventricle and left ventricle during positive- pressure ventilation with varying levels of positive end-expiratory pressure. Crit Care Med 17:205–210PubMedCrossRefGoogle Scholar
- 7.Vieillard-Baron A, Chergui K, Rabiller A, Peyrouset O, Page B, Beauchet A, Jardin F (2004) Superior vena cava collapsibility as a gauge of volume status in ventilated septic patients. Intensive Care Med (http://dx.doi.org/10.1007/s00134-004-2361-y)
- 8.Feissel M, Michard F, Faller JP, Teboul JL (2004) The respiratory variation in inferior vena cava diameter as a guide to fluid therapy. Intensive Care Med (http://dx.doi.org/10.1007/s00134-004-2233-5)
- 9.Barbier C, Loubières Y, Schmit C, Hayon J, Ricôme JL, Jardin F, Vieillard-Baron A (2004) Ability of respiratory changes in inferior vena cava diameter to predict fluid responsiveness in ventilated septic patients. Intensive Care Med (http://dx.doi.org/10.1007/s00134-004-2259-8)