The Indicator Dilution Method Measures Fluid Compartment Size

Sugar Crush Detox

Get Instant Access

The indicator dilution method can be used to determine the size of body fluid compartments (see Chapter 14). A known amount of a substance (the indicator), which should be confined to the compartment of interest, is administered. After allowing sufficient time for uniform distribution of the indicator throughout the compartment, a plasma sample is collected. The concentration of the indicator in the plasma at equilibrium is measured, and the distribution volume is calculated from this formula

Volume = Amount of indicator/ Concentration of indicator

If there was loss of indicator from the fluid compartment, the amount lost is subtracted from the amount administered.

To measure total body water, heavy water (deuterium oxide), tritiated water (HTO), or antipyrene (a drug that distributes throughout all of the body water) is used as an indicator. For example, suppose we want to measure total body water in a 60-kg woman. We inject 30 mL of deuterium oxide (D2O) as an isotonic saline solution into an arm vein. After a 2-hr equilibration period, a blood sample is withdrawn, and the plasma is separated and analyzed for D2O. A concentration of 0.001 mL D2O/mL plasma water is found. Suppose during the equilibration period, urinary, respiratory, and cutaneous losses of D2O are 0.12 mL. Substituting these values into the indicator dilution equation, we get

Total body water = (30 - 0.12 mL D2O) X 0.001 mL D2O/mL water = 29,880 mL or 30 L

Therefore, total body water as a percentage of body weight equals 50% in this woman.

To measure extracellular water volume, the ideal indicator should distribute rapidly and uniformly outside the cells and should not enter the cell compartment. Unfortunately, there is no such ideal indicator, so the exact volume of the ECF cannot be measured. A reasonable estimate, however, can be obtained using two different classes of substances: impermeant ions and inert sugars. ECF volume has been determined from the volume of distribution of these ions: radioactive Na+, radioactive Cl_, radioactive sulfate, thio-cyanate (SCN~), and thiosulfate (S2O32-); radioactive sulfate (35SO42-) is probably the most accurate. However, ions are not completely impermeant; they slowly enter the cell compartment, so measurements tend to lead to an overestimate of ECF volume. Measurements with inert sugars (such as mannitol, sucrose, and inulin) tend to lead to an underestimate of ECF volume because they are excluded from some of the extracellular waterâ€”for example, the water in dense connective tissue and cartilage. Special techniques are required when using these sugars because they are rapidly filtered and excreted by the kidneys after their intravenous injection.

Cellular water cannot be determined directly with any indicator. It can, however, be calculated from the difference between measurements of total body water and extracellular water.

Plasma water is determined by using Evans blue dye, which avidly binds serum albumin or radioiodinated serum albumin (RISA), and by collecting and analyzing a blood plasma sample. In effect, the plasma volume is measured from the distribution volume of serum albumin. The assumption is that serum albumin is completely confined to the vascular compartment, but this is not entirely true. Indeed, serum albumin is slowly (3 to 4% per hour) lost from the blood by diffusive and convective transport through capillary walls. To correct for this loss, repeated blood samples can be collected at timed intervals, and the concentration of albumin at time zero (the time at which no loss would have occurred) can be determined by extrapolation. Alternatively, the plasma concentration of indicator 10 minutes after injection can be used; this value is usually close to the extrapolated value. If plasma volume and hema-tocrit are known, total circulating blood volume can be calculated (see Chapter 11).

Interstitial fluid and lymph volume cannot be determined directly. It can be calculated as the difference between ECF and plasma volumes.

0 0

The Sugar Solution

Curb Sugar Cravings Once And For All With These Powerful Techniques. Sugar sensitive people might be low in specific neurochemicals that help us feel calm, centered, confident, and optimistic. Sugar is a drug that temporarily makes the sugar sensitive feel better, but with damaging consequences.

Get My Free Ebook

Responses

• tesmi
What volume cannot be measured using indicator dilution technique?
8 years ago
• romilda
Who discovered indicator dilution method of estimation extracellular fluid?
8 years ago
• mentha t
What is indicator dilution techniques,how is it applied in the measurement of total body water?
4 years ago
• Quintilia
How to measure total body water using triated water?
3 years ago
• Mathilda
How is indicator dilution technique applied in the measurement of total body water?
3 years ago
• sirpa
What indicators are used in measuring the volume of body fluid compartment?
3 years ago
• chica
What is Dilution method in fluid compartments?
3 years ago
• arsi haapalainen
How to measure body fluids using indicator dilution method?
3 years ago
• dehab
What is dye dilution method in body fluid?
3 years ago
• claudia
WHAT is indicator dilution method in.measurement of body fluid?
3 years ago
• murron
What indicator is used for measuring body water in dilution technique?
3 years ago
• nick
Why deuterium used in indicator dilution?
3 years ago
• dirk
What is the indicators of fluid compatment?
3 years ago
• christian
What are the indicators for the measurement of plasma?
3 years ago
• gabriele
What are substance use to measure body fluids compartments with there suitability limitations?
3 years ago
• Bellisima Roper
How to measure body volume using indicstor dilution method?
3 years ago
• Henna
How is water measured in our body using the dilution principle?
3 years ago
• ansegar
How to measure body water using dilution principle?
3 years ago
• niklas
How body fluid is measured according to dilution principle?
3 years ago
• Szymon
How to measure body fluid using dilution method?
3 years ago
• stephan
Can water be used to dilute with power indicator?
2 years ago
• anneli ketterer
What dye is the most accurate in measuring ECF fluid?
2 years ago
• Filibert
Can ECF be estimated by the dilution of D2o?
2 years ago
• Amanda
Why D2O is used as indicator to measure Total body water?
2 years ago
• catherine
Can total body water be measured by an indicator using dilution technique aminopyrine?
2 years ago
• wanda
Is indicator dilution method used in measuring total bodywater?
2 years ago
• SEAN
Why is indicator dilute principle use in the measurement of body fluid volume?
2 years ago
• Yolanda
Why indicator dilution principle is used in measurement of body fluid volume?
2 years ago
• mareta
Why is indicator dilution principle used in measuring body fluid volume?
2 years ago
• destiny scott
Why do we use indicator dilute principle to measure body fluid volume?
2 years ago
• Lea
Why is indicator dilution method principle used in measurement of body fluid?
2 years ago
• dario
Can total body water be measured directly with a single indicator?
2 years ago
• Tommy Kattilakoski
What indicators can be.used to measure total body water?
2 years ago
• doreen
How is indicator dilution technique applied in the measurements of extracellular fluid?
1 year ago
• wolfgang
How to determime body fluid compartment using dye dilution method?
1 year ago
• Tina
How to measure indicator dilution method intra cellular fluid volume?
1 year ago
• How to measure the conc of d20 in water in measuring total body fluid?
12 months ago
• james
How to mesure body fluid compatment?
8 months ago
• macaria
How the dilution method works in measuring body compartments?
8 months ago
• camilla
How to measure fluid in take and utine out put for uriologh testing for three days?
3 months ago
• Samuel Tesmi
How to measure fluid compartment sizes?
3 days ago
• carla
How do we measure fluid compartment sizes in our body?
3 days ago