Figure 1
From: Perioperative fluid therapy: a statement from the international Fluid Optimization Group

Perspective of the anesthesiologist’s tools (fluid and drugs) and the physiologic targets of these tools (blood volume, the heart, and blood vessels). The heart has two components (contractility and rate), and the blood vessels have two major characteristics (compliance and resistance). It is blood volume, heart, and blood vessels that produce pressure, flow, and oxygen delivery, while the intermediate physiologic functions and their metrics provide a means of assessing the cardiovascular state and how effective fluids are likely to be.