Hemochron® Microcoagulation System Activated Partial Thromboplastin Time (aptt) Heparin Response Study Intended Use

Heparin Response Study: APTT

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Hemochron^® Microcoagulation System

Activated Partial Thromboplastin Time (APTT)

Heparin Response Study

Intended Use:
The Heparin Response Study can be used to evaluate system performance. This in vitro testing consists of adding whole blood to serial dilutions of heparin (range: up to 1.5 U/mL).
The Analytic Measurement Range (AMR): 20 – 399.9 plasma-equivalent seconds.
This Study may not be required by the inspecting agency; each site should determine if this study is mandatory.
As each individual has a unique response to heparin as the APTT results in the higher concentrations may exceed the Analytic Measurement Range (AMR) and will yield an “Out of Range-Hi” message on the Hemochron^® Signature Elite and the Signature+ instruments. These results can be recorded as such but must be understood this result is a reflection of the donor’s sensitivity to heparin and not an instrument malfunction.

Materials:
Hemochron^® APTT cuvettes

Plastic test tubes with caps

USP Heparin (concentration 1000 IU/mL)

Normal saline

Syringe needle (not less than 23 Gauge)

Plastic syringe (capacity to be determined by total volume necessary)

Precision pipettes capable of measuring to a minimum of 10 μL

Plastic transfer pipettes

Graduated pipettes able to measure in 1 mL increments

Procedure:

1. 
   Obtain 5 Hemochron Jr APTT cuvettes (optional: 6 APTT cuvettes for the full study) for each HEMOCHRON Signature series instrument being tested. The cuvettes must be at room temperature before opening the pouch.
   

2. 
   Dilute the heparin to a concentration of 100 U/mL. This is accomplished by adding 9 mL normal saline to 1 mL of the USP heparin (concentration 1000 U/mL). The diluted heparin preparation must be well-mixed and at room temperature prior to use.
   

3. 
   Label 5 (optional: 6) plastic test tubes in the following manner: “A”, “B”, “C”, “D” and “E” (optional: F). Dispense the following quantities of the diluted heparin into the respective test tubes. The final concentration of heparin in the plastic test tubes after the addition of 1 mL fresh whole blood can be found in Table 1.
   

Table 1 – Basic Dilution Guide*

Tube	Amount of Heparin (μL)	Whole Blood (mL)	Heparin (Units/1 mL Blood)
A	0	1.0	0
B	2.5	1.0	0.25
C	5.0	1.0	0.5
D	7.5	1.0	0.75
E	1.0	1.0	1.0
F (optional)	1.5	1.0	1.5

• 
  Better performance may be observed by using larger quantities of blood; the heparin amount must be increased proportionately to maintain the final concentrations as listed.
  

4. 
   Draw the necessary blood volume via venipuncture using the syringe method; dispense the appropriate volume of blood into each tube that contains the described amount of diluted heparin.
   

5. 
   For the tubes containing heparin, mix the diluted heparin with the blood by gentle end-to-end inversion in the capped plastic tube before use.
   

6. 
   Tube “A” must be tested immediately. Transfer to the testing well of the cuvette by a plastic transfer pipette.
   

NOTE: in lieu of a tube, the sampling may be directly from the syringe.

7. 
   Test the remaining tubes in the order of lowest to highest concentration of heparin; mix each tube thoroughly before testing.
   

8. 
   Record the results for each instrument tested.
   

9. 
   The resulting data may be recorded on Table 2.
   

Notes

• 
  The actual APTT results obtained will vary among donors due to the individual responses to heparin. The optional heparin concentrations of 1.5 U/mL may yield results that exceed the reportable range of the system.
  

• 
  The heparin manufacturer source and lot number of the heparin may also affect results.
  

• 
  The maximum concentration of heparin at which donor blood will clot is dependent upon physiologic characteristics of the donor.
  

Table 2 – Data Collection

Tube	Amount of Heparin (μL)	Whole Blood (mL)		Total Heparin Concentration		Results
A				0
B				0.25
C				0.5
D				0.75
E				1.0
F (optional)				1.5
Heparin Manufacturer			Lot No.		Exp Date

Serial Number ________________________ Date _____________________
Cuvette Lot Number ___________________ Exp Date _________________

Tube	Amount of Heparin (μL)	Whole Blood (mL)		Total Heparin Concentration		Results
A				0
B				0.25
C				0.5
D				0.75
E				1.0
F (optional)				1.5
Heparin Manufacturer			Lot No.		Exp Date

Serial Number_________________________ Date ____________________
Cuvette Lot Number ___________________ Exp Date ________________

Tube	Amount of Heparin (μL)	Whole Blood (mL)		Total Heparin Concentration		Results
A				0
B				0.25
C				0.5
D				0.75
E				1.0
F (optional)				1.5
Heparin Manufacturer			Lot No.		Exp Date

MSIG: 75 9/2012