Diuresis used to increase urine output and decrease extracellular fluid volume. Substances in the circulation can also increase the amount of circulating fluid by increasing the osmolarity of the blood. This has the effect of pulling water from the interstitial space, making more water available in the blood and causing the kidney to compensate by removing it as urine. In hypotension, often colloids are used intravenously to increase circulating volume in themselves, but as they exert a certain amount of osmotic pressure, water is therefore also moved, further increasing circulating volume. As blood pressure increases, the kidney removes the excess fluid
Base excess data. The term and concept of base excess were first introduced by Poul Astrup and Ole Siggaard-Andersen in 1958. Base excess can be estimated from the bicarbonate concentration ([HCO]) and pH by the equation: formula_1 with units of mEq/L. The same can be alternatively expressed as formula_2 Calculations are based on the Henderson-Hasselbalch equation: Ultimately the end result is: Base excess beyond the reference range indicates Blood pH is determined by both a metabolic component, measured by base excess, and a respiratory component, measured by PaCO (partial pressure of carbon dioxide). Often a disturbance in one triggers a partial compensation