Question

Finn is a 50 year-old man, who was scheduled for a colon resectioning. The preop orders included a CBC and a crossmatch for 2 units. The CBC report showed his WBC count to be 14.5 x10⁹/L. His hemoglobin was 14.0 g/dL, hematocrit: 43%, and a platelet count, 19,000/uL. The blood bank typed him as O positive and crossmatch 2 unites of O positive packed cells.

1. Is additional component therapy other than the 2 unit crossmatch indicated? Why?
2. How many units of the additional therapy would you recommend?
3. Calculate the incremental change you would expect after transfusing, assuming he is a 70-kg man.
4. If 1 hour after transfusion, his CBC changes to a hemoglobin of 14.0 g/dL and platelet count of 40,000uL, what is his corrected count increment (CCI)?
   1. Is this normal, higher or lower than expected
   2. What does this indicate?
5. What are the storage requirements and shelf life of platelets (pooled or random/apheresis), fresh frozen plasma, red blood cells and cryo?

Answer 1

The platelet count of the patient is 19000/uL, which is low. (Normal range = 1.5 to 4 lakh / uL).

In addition to packed red blood cells, thr patient requires platelet transfusion, since the platelet count is low.

Indications for platelet transfusion in Adults :

a. Platelet count < 10,000 - 20,000/µL

b. Platelet count < 50,000/µL in the presence of  bleeding

c. Platelet count < 50,000/µL & immediately prior to any invasive procedure.

d. Platelet count < 100,000/µL in the presence of CNS or retinal bleeding .

e. Platelet count < 100,000/µL & immediately prior to invasive CNS or retinal procedures.

Platelets Dosing

1. Adult dose : one unit of Platelets Pheresis or one unit of pooled Platelets.

2. Pediatric dose : 10mL/kg body weight up to 10-15 kg body weight; > 15 kg = adult dose.

3. Neonate dose : 10mL/kg body weight + 7mL for tubing.

Component	Volume	Content	Storage	Expected Increment in platelet count
Platelets Pheresis	250mL	≥ 3x1011 platelets	20-24o C (room temperature) with continuous agitation	30,000-60,000/µL
Whole blood derived Platelets	50mL	≥ 0.55x1011 platelets	20-24o C (room temperature) with continuous agitation	10,000/µL
Pooled Platelets	200mL	≥ 3x1011 platelets	20-24o C (room temperature) with continuous agitation	30,000-60,000/µL

Guidelines recommend a platelet count threshold of 50 x 10⁹/L prior to major surgery (and 100 x 10⁹/L prior to surgery involving the brain or eyes).

Hence, one unit of pooled platelets/ pheresis is recommended in this patient, to raise the platelet count by 30000-60000/µL.

Corrected count increment (CCI) and percent platelet recovery (PPR) are measures of response to platelet transfusion that "correct" the count increment for blood volume and number of platelets transfused.

Platelet count increment is the 15-60 minute post-transfusion minus pre-transfusion platelet counts.

A] Corrected Count Increment (CCI) for platelets:

CCI = (platelet increment per ul) x (body surface area in m²)/ number of platelets transfused (x 10¹¹)

B] Posttransfusion [Percent] Platelets Recovery (PPR):

a. Platelet count increment is the 15-60 minute post-transfusion minus pre-transfusion platelet counts .

b. Blood Volume (BV) is in liters (L).

c. Number (No.) of platelets transfused is presumed to be 3x10¹¹ or the exact count if known .

d. Refractoriness suspected when PPR <50% of expected increment.

PPR = [(platelet increment per ul) x BV] / No of platelets transfused.

In this case, CCI = [(40000 - 19000) 2 ] / 3 = 14000.

( Note :In this case, the exact BSA cannot be calculated, since the heoght is not given. An average adult has a BSA of approximately 2.0 m2 .

1 unit of pooled platelet = 3x10¹¹ platelets).

(a)

The CCI value is more than 7500.This indicates that there in no platelet refractoriness.

Platelet refractoriness is suspected when the CCI for 15-60 min post transfusion platelet count is:

i. < 5.0-7.5 x 109 m ² /L (< 5,000-7,500 m² /μL) after two consecutive platelet transfusions.

ii. On rare occasion, a 24 hour post-transfusion platelet count is used for the increment and then CCI < 4.5 x 109 m ² /L (4,500 m ² /μL) suggests refractoriness.

(b)

Blood product type	Storage condition	Shelf life
Platelet	Platelets Pheresis : 0-24o C (room temperature) with continuous agitation Pooled Platelets :  0-24o C (room temperature) with continuous agitation	5 days
Fresh frozen plasma	Frozen (< - 18 o C ) within 24 hours of being donated.	1 year
RBC	1-6o C	Up to 42 days ( depending upon the anticoagulant used).
Cryoprecipitate	Frozen ( < - 18 o C)	1 year