OREGON HEALTH & SCIENCE UNIVERSITY Health Care System

Point of Care (POC)

ACTIVATED CLOTTING TIME (ACT), WHOLE BLOOD, HRACT BY MEDTRONIC ACT II

Principle

The Medronic Automated Coagulation Timer II (ACTII) system is a microprocessor controlled electro-mechanical coagulation instrument designed to determine coagulation endpoints in whole blood. The ACT II detects clot formation by measuring the rate of fall of the plunger-flag mechanism contained in each cartridge channel. A photo optical system located in the cover assembly of the instrument detects this rate of fall.

ACT II cartridges use specially prepared and standardized kaolin as the activating agent. The HR-ACT (High Range ACT) has a response to heparin above 1-1.5 u/ml, which favors use in catheterization laboratories and vascular surgery.

Specimen Requirements

Fresh whole blood collected in a syringe. The syringe should have a 23 or 21 gauge needle. DO NOT use excessive force when expelling the blood specimen through the needle. This may lead to sample hemolysis.

Testing requires 0.8 ml of blood (0.4 ml per channel).

1. UAC/ Arterial Line When obtaining an ACT specimen from an UAC or arterial line, aspirate 2.5 ml blood to clear the catheter before drawing the sample. Always draw the ACT before placing a heparinized syringe in the stopcock for an ABG. After drawing the sample, flush the line with NS to clear. (Blood used to clear UAC can be re-administered unless clotted or contaminated.)

Test the specimen immediately. Baseline (unheparinized) samples should be run within one minute. Heparinized samples should be run within two minutes.

Interfering Substances

1. Do not collect blood from a heparinized access line, lock or in-dwelling heparin line, as heparin contamination will prolong the ACT.
2. IV lines not adequately flushed before drawing test sample.
3. Poor technique when collecting specimens and performing the test.
4. Clotted or partially clotted blood.
5. Unsuspected anticoagulation with either heparin or warfarin.
6. Samples with any of the following characteristics should be discarded and a fresh sample collected.
   1. Sample contamination with tissue thromboplastin.
   2. Sample contamination with indwelling intravenous solutions.
   3. Samples with visible clotting or debris accumulation.

Linearity

The manufacturer states that the ACT II demonstrates linear correlation to the anticoagulation effects of heparin between 1.0 and 6.0 units/cc of blood. Timer range is from 0 to 999 seconds.

Normal and Therapeutic Ranges

Alert Values

Critical/Alert Values are those results demonstrating such variance from normal as to represent a pathophysiological state with potential of being life threatening unless action is taken quickly. These results must be immediately reported to the care provider following current nursing policies and procedures. This notification must be documented in the test record

1. Report all ACT results outside of the therapeutic range limits to the physician immediately.

Quality Control

Quality control consists of the ACT TRAC electronic quality control (EQC), Whole Blood CLOT TRAC quality control, and temperature verification. Two levels of quality control must be run every eight hours of patient testing. This can be accomplished using EQC in most cases.

When performing QC, make sure that your user ID # (5 digit employee #) is used.

1. Electronic Quality Control (EQC), Medtronic ACTtrac

Two different time selections on the ACT TRAC must be run every eight hours of patient testing. Normal (98-102) and Abnormal (190-204) are the two settings to be used.

EQC Procedure:

1. The INCUBATE option on the ACTII must be “OFF” when performing EQC.

2. Set the time selector on the ACT TRAC to the desired time using the “Time Select Knob”.

3. Select “100 sec” or “200 sec” on the ACTII depending on the time selected on the ACT TRAC.

4. Place the ACT TRAC into the actuator heat block and push the heat block back.

5. The push rods of the instruments push the cartridge plugs “up” so that the cartridge reagent is properly injected into the cartridge reagent chamber. If the instrument is properly adjusted with respect to the push rods, the STATUS indicator will flash three times.

6. If the STATUS indicator does not flash three times or if the STATUS indicator comes on and stays on, repeat the test. If these errors are repeated, contact the Medtronic Technical Service at 1-800-525-7007.

7. Upon termination of the test, the instrument will sound an audible tone and the clotting time results will be displayed. The instrument will detect simulated clots in both channels.

8. Check that the results obtained are within the range.

9. Repeat testing using the second time setting.

10. If the QC results for both selected times are within the acceptable limits, patient testing may be performed. Do not perform any patient testing until both of the selected time settings are within limits.

NOTE:

If the “Stop” button is pressed on the ACT II instrument before the ACT TRAC has finished its test cycle, the ACT TRAC battery cover/battery must be removed and reinserted to reset the device.

2.  Whole Blood Controls, CLOT TRAC

1. Perform whole blood controls once a month on opened boxes of HRACT cartridges.
2. Perform whole blood controls each time a box of cartridges with a new lot number is opened.

Whole blood controls for the HRACT cartridges are:

1. The CLOT TRAC HR Control is the normal control.
2. The CLOT TRAC HR High Abnormal Control is the abnormal control.

Procedure for Whole Blood QC

1. Remove required number of CLOT TRAC HR Control and de-ionized water vials from refrigerated storage.

2. Allow vials to come to room temperature, approximately 10 minutes.

3. To each vial of lyphilozed control add 1.8 ml of de-ionized water using a syringe. DO NOT AGITATE THE CONTROL UNTIL COMPLETELY REHYDRATED.

4. Allow at least 2 minutes for adequate rehydration. It may be necessary to increase the rehydration time up to 10 minutes under certain environmental conditions (such as a cold room) in order to assure proper rehydration. Failure to do so may lead to an improperly reconstituted control, which will give erratic results.

5. Once rehydrated shake the control vigorously until red blood cells are uniformly dispersed and the control is completely reconstituted.

6. Do not use controls past the indicated expiration date. Once reconstituted, the HR control is stable for 2 hours at room temperature, 15-25°C. The HR Abnormal control is stable for 1 hour at room temperature.

7. Shake or tap the HRACT cartridge to suspend the cartridge reagents.

8. Transfer 0.4 ml of the reconstituted control, using a syringe, into each chamber of the cartridge. Fill to between the fill lines etched on each channel body.

9. Place the filled cartridge into the instrument and turn the INCUBATE option to “ON” and close the actuator door. The test will automatically initiate after a 300 second incubation period.

10. Report QC result in seconds on QC log sheet.

11. Record cartridge lot number/expiration date, QC lot number and acceptable QC ranges.

12. Ensure that control results are within CLOT TRAC established limits. There should be less than 10% variation between channels.

13. If control results are not within established limits or channel variation is more then 10% repeat control after reviewing limitations of procedure at the end of QC section.

14. Repeat steps a. – m. for CLOT TRAC High Abnormal Control with HRACT cartridge.

Limitations of Procedure

Results are dependent on good technique. Strict adherence to rehydration requirements is recommended.

Failure to obtain in range quality control invalidates the use of both the instrument and the assay until the problem is resolved.

If QC fails:

1. Ensure that the cartridge, instrument and control are at 37°C +/- 5°C before initiating the test.

2. Ensure that all controls, cartridges and CaCl₂ have not exceeded their respective expiration dates.

3. Ensure that the control was properly reconstituted.

4. Inspect control for visible clot formation.

5. Repeat the test if the above criteria have been met.

6. If repeat QC fails, do not perform patient testing.

7. Repeat QC test using new lot number of cartridges if available.

8. If repeat fails rerun using new lot # of QC if available.

9. If this also fails, do not perform patient testing contact Medtronic Technical Service at 1-800-525-7007.

10. Document all action taken in QC Log Book.

3. Well Temperature Testing Check Performed each day of patient testing.

1. Record instrument temperature. Temperature should be 37 ± 0.5°C.
2. If temperature is out of range, perform heat block temperature calibration.

Procedure

If fresh whole blood tests are normally performed, the instrument should be set for non-incubate condition and the front panel incubate switch used to engage the incubate condition when control samples are run. In this case, the incubate mode must be engaged before each test, since the instrument defaults to the non-incubate condition following the termination of the test.

1. When performing a fresh whole blood test, pre-warm the cartridge, without the test sample for at least 3 minutes. The cartridge may be pre-warmed for up to 12 hours without affecting its performance.

2. Obtain sample per Blood Sampling.

3. Tap appropriate cartridge to mix the reagents in reagent chamber.

4. Inject the 0.4 ml of sample into each reaction chamber (fill to between lines etched on each chamber). Allow the sample to flow down the back of the chamber taking care to avoid sample on the flag or the plunger assembly. A 1” 18ga blunt needle can be used.

5. Insert the cartridge into the actuator heat block and rotate the heat block to the closed position.

6. The incubate OPTION must be off.

7. The instrument begins testing for the formation of a clot and measures the amount of elapsed time since the initiation of the clot-timing portion of the test.

8. Results can be displayed as the individual channel clotting times or as the average difference of the determinants by pressing the DISPLAY key.

Results Reporting

1. Accuracy and precision depends on the quality of the blood sample, testing technique, and ambient conditions such as temperature.

2. Duplicate samples in the 0-600 second range should agree within 10%. If % difference is greater than 10% repeat test.

3. Reportable range for ACT II test is 20-999 seconds.

4. All ACT results are reported to staff surgeon and staff anesthesia.

5. Record results in the Patient's record.

Reporting Abnormal Results

1. Clotting times which exceed 600 seconds are not considered to be reliable enough to determine heparin levels by coagulation times.

2. Results that exceed “999” should be reported as “greater than 999”.

3. Results that appear to be inconsistent with patient therapy should be viewed as questionable and the test should be immediately repeated.

Calibration

Heat Block Calibration and Verification. Perform Monthly.

1. Turn the Automated Coagulation Timer II on. Allow the instrument to warm up for 5-10 minutes. The temperature display will read 37°C.

2. Use the Temperature Verification Cartridge and proceed with Step 4,

3. Wait for temperature equilibration to occur (about 15 minutes) and check the thermometer reading.

4. The instrument temperature and actual measured temperature should both read within 36.5-37°C. The measured temperature should be within +/- 0.5°C of the instrument temperature.

5. If there is a discrepancy between the temperature of the heat block and the display, the display may be adjusted with a screwdriver using the bottom panel temperature adjustment knob.

6. Clockwise rotation increases the temperature of the heat block and counterclockwise rotation decreases the temperature of the heat block

Reagents

1. Activated Clotting Time Cartridge

1. When refrigerated (2-8°C), the cartridges are stable until the marked expiration date.
2. Do not use cartridges if they appear discolored, cracked or disfigured, or if the reagent appears to have evaporated or contaminated.

2. CLOT TRAC Coagulation Controls, HR Normal and HR Abnormal

Storage requirements:

1. Control should be stored at 2-10°C until use.
2. When refrigerated at 2-10°C, the vials are stable until the marked expiration date.
3. Continued exposure to ambient temperatures will shorten the shelf life.
4. Reconstituted vials are stable for 2 hours at 15-25°C.

Maintenance

Inspect and clean the cartridge opening weekly and as otherwise needed.

1. If blood should get into the actuator assembly it is critical that the instrument be cleaned as soon as possible.
2. Use Actuator Cleaning Kit to clean actuator.

   1. Dip swab, provided in the packet, in the Liqui-Nox Solution.

   2. Swab the flag lift wire, removing all blood.

   3. Swab inside the actuator cover, especially the detector and emitter area of the photo-optical system.

   4. Remove excess Liqui-Nox with a dry swab.

   5. If blood should get into the photo-optical detector and emitter area and cannot be removed with a swab, error code “4” may be displayed. If this occurs, contact the Medtronic Blood Management Technical Service at 1-800-525-7007.

References

1. ECMO, second edition, Zwischenberger, MD, Steinhorn, MD, Bartlett, MD, 2000.
2. Medtronic Activated Coagulation Timer Manual, 2000.
3. Medtronic ACT TRAC pamphlet, 2000.
4. Medtronic CLOT TRAC Coagulation Control inserts, 2004.

Revised 7/15/04

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