Measure the fraction of RBC tagged with Cr 51.Inject a known amount of Cr 51 labeled RBC intravenously.Use Chromium 51 labeled RBC as the indicator.Measuring red cell volumeNote: measuring is different from calculating something In a healthy 70 kg adult male, plasma volume (measured using the Evans Blue dye) was found to be 3000 ml.Blood volume = plasma volume × 100 / (100 – Hct) Image from īlood volume = plasma volume × (100/100-Hct).Volume of cells: packed cell volume (PCV).What is the relationship between blood volume and plasma volume? In health, the total volume of transcellular fluids is ICF volume = Total body water – ECF volume.ISF volume = ECF volume – plasma volume.Cannot be measured it is calculated (estimated).How would you measure interstitial fluid (ISF) volume? Thus, volume of distribution (Vd) of sucrose = A / C = 95 mg / 0.01 mg/ml = 9500 ml = 9.5 L (= ECF volume).Concentration in plasma after mixing (C) = 0.01 mg/ml.If 5 mg has been metabolized during this period, then, what is the ECF volume? The plasma sucrose level after mixing is 0.01 mg/ml. 100 mg of sucrose is injected into a 70 kg man.Indicators used for measuring plasma volume, ECF volume and total body water Volume of distribution Vd of the indicator = Amount of indicator injected (A) Concentration in blood after mixing (C).Determine the final steady state concentration (C) of this indicator in blood.Administer a known amount (A) of a substance that will get distributed in a particular body fluid compartment.
Principle: Indicator-dilution principle.Plasma ECF Interstitial Fluid About 3/4th of ECF volume Intracellular Fluid 2/3 of total body water is inside cellsīody fluid volumes in a healthy 70-kg adult male Body Fluid Compartments – Part 1Body Composition E.S.Prakash, Faculty of Medicine, AIMST University E-mail: Note to Readers – This is one of the lectures in the Molecular & Cellular Basis of Medicine course, Element 2 in Term 1 of Year 1 of the MBBS programme.
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