Transfusion Calculations: Difference between revisions
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Used to determine the amount of units that statistically need to be searched in order to find antigen-compatible units. | Used to determine the amount of units that statistically need to be searched in order to find antigen-compatible units. | ||
<chem display=" | <chem display="block">\text{Units searched}=\frac{\text{Units required}}{(1-f_1)(1-f_2)(...)}</chem> | ||
Where f<sub>1</sub> is the frequency of antigen 1, f<sub>2</sub> is the frequency of antigen 2, etc. For example, if 2x K- units are required and the frequency of K is 8%, then the equation is: | Where f<sub>1</sub> is the frequency of antigen 1, f<sub>2</sub> is the frequency of antigen 2, etc. For example, if 2x K- units are required and the frequency of K is 8%, then the equation is: | ||
<math>\text{Units searched}=\frac{2}{(1-0.08)}=\frac{2}{0.92}=2.17=3</math> | <math display="block">\text{Units searched}=\frac{2}{(1-0.08)}=\frac{2}{0.92}=2.17=3</math> | ||
The final number is rounded up to the nearest whole number. | The final number is rounded up to the nearest whole number. | ||
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First, the estimated volume of fetal cells in circulation is calculated: | First, the estimated volume of fetal cells in circulation is calculated: | ||
<math>V_\text{fetal blood}=\frac{\text{Number of fetal cells per 2000 cells}}{2000}*5000</math> | <math display="block">V_\text{fetal blood}=\frac{\text{Number of fetal cells per 2000 cells}}{2000}*5000</math> | ||
The proportion of fetal cells per 2000 cells total is calculated and then multiplied by the approximate maternal blood volume. | The proportion of fetal cells per 2000 cells total is calculated and then multiplied by the approximate maternal blood volume. | ||
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Then, the RhIG dose is calculated (based on one 300 µg dose of RhIG, which protects against 30 mL of fetal blood) along with an additional 1 unit to provide a safety margin. | Then, the RhIG dose is calculated (based on one 300 µg dose of RhIG, which protects against 30 mL of fetal blood) along with an additional 1 unit to provide a safety margin. | ||
<math>RhIG=\frac{V_{fetal}}{30}+1</math> | <math display="block">RhIG=\frac{V_{fetal}}{30}+1</math> | ||
Revision as of 18:03, 5 February 2025
Compatible Units Calculation
Used to determine the amount of units that statistically need to be searched in order to find antigen-compatible units.
Where f1 is the frequency of antigen 1, f2 is the frequency of antigen 2, etc. For example, if 2x K- units are required and the frequency of K is 8%, then the equation is:
The final number is rounded up to the nearest whole number.
Rh Immunoglobulin Calculation
Used to determine the amount of Rh Immunoglobulin to be provided to the mother based on fetal-maternal hemorrhage.
First, the estimated volume of fetal cells in circulation is calculated:
The proportion of fetal cells per 2000 cells total is calculated and then multiplied by the approximate maternal blood volume.
Then, the RhIG dose is calculated (based on one 300 µg dose of RhIG, which protects against 30 mL of fetal blood) along with an additional 1 unit to provide a safety margin.