MPI in platelets per µL =
= (total number of platelets transfused) * (fractional recovery of the transfused platelets) / (1000 * (blood volume in mL))
total number of platelets transfused =
= (number of platelet products transfused) * (average number of platelets per product)
|
Patient Condition
|
Fractional Recovery
|
|
normally sized spleen
|
0.62 to 0.67
|
|
asplenic
|
0.91
|
|
splenomegaly
|
0.23
|
where:
• The 1,000 in the denominator is for converting mL blood volume to µL.
• Fractional recovery ranges from 0 (no survival) to 1 (perfect survival).
• Petz (1996) used the following equations (page 383) to estimate blood volume from body weight = 70.5 * (weight in kilograms).
• Petz used the following equations to estimate blood volume from body surface area: for men = 2725 * (BSA in square meters); for women = 2507 * (BSA in square meters)
percentage platelet recovery =
= (platelet increment observed per µL) / (MPI) * 100% =
= 1000 * (blood volume in mL) * (platelet increment observed per µL) * 100% / ((number of platelets transfused) * (fractional recovery of transfused platelets))
If the body weight in kilograms is known:
percentage platelet recovery =
= 7 * 10^4 * (platelet increment observed per µL) * (body weight in kilograms) * 100% / ((number of platelets transfused) * (fractional recovery of transfused platelets))
If the body surface area in square meters is known:
percentage platelet recovery for men =
= 2.725 * 10^6 * (platelet increment observed per µL) * (body surface area in square meters) * 100% /( (number of platelets transfused) * (fractional recovery of transfused platelets))
percentage platelet recovery for women =
= 2.507 * 10^6 * (platelet increment observed per µL) * (body surface area in square meters) * 100% / ((number of platelets transfused) * (fractional recovery of transfused platelets))
