Clinical Procedure: Anticoagulation Point-of-Care Test CoaguChek System Test

Transcription

1 Clinical Procedure: Anticoagulation Point-of-Care Test Principle One method for monitoring the international normalized ratio (INR) is by using a capillary blood test as directed by the CoaguChek System test and monitor. After placing a drop of fresh whole blood on the test strip, the blood is drawn into the reaction chamber and mixed with reagents that cause coagulation to begin. In the test strip, tiny iron particles are mixed with the sample. Alternating magnetic fields cause the iron particles to move within the sample. The endpoint is reached when the blood clot stops the iron particles from moving. Specimen Capillary Whole Blood Specimen must be used immediately after collection Equipment / Reagent Needs 1. CoaguChek System monitor 2. CoaguChek System test strips When using test strips from a new unopened box, change the test strip code chip. The first three numbers after the lot symbol on the test strip pouch should match the numbers on the test strip code chip. To install the test strip code chip, follow the instructions in the User s Manual. 3. CoaguChek Test strip code chip 4. Supplies for capillary collection Lancing device and lancet Capillary tube (free of anticoagulants) Capillary bulb Storage and Stability 1. Keep test strips in the original sealed foil pouches. 2. Store test strips in refrigerator at +2 o C to +8 o C (+36 o F to +46 o F) until ready to use. Do not freeze. When stored at room temperature (below 32 o C or greater than 90 o F), test strips are stable for 60 days or until the expiration date, whichever comes first. 3. Remove only the necessary number of foil pouches from the refrigerator needed to perform a test. Allow at least 5 minutes for the sealed pouch to reach room temperature (18 to 32 o C or 65 to 90 o F) before opening the foil pouch for testing. 4. Once the foil pouch has been opened, use the strip within four minutes. Page 1 of 5 12/04

2 Procedure I. Instrument Set Up A. Set monitor on a flat surface, free of vibrations. B. Turn the monitor on and follow the prompts to insert a test strip. C. Open the foil pouch at the tear mark on the side and remove the test strip. D. Insert the test strip into the monitor, printed side up, and push it in until it stops. E. Wait until you are prompted to apply the sample. F. Prepare to collect the fresh whole blood. II. III. Capillary Sample Collection A. Use lancing device to puncture the fingertip and gently squeeze finger until a hanging drop of blood forms. B. Fill capillary tube halfway. 1. Avoid getting air bubbles into the sample. 2. Do not touch the bulb during sample collection. If blood gets into the capillary bulb during collection, discard the bulb. C. When the monitor prompts for sample application, hold the capillary tube directly over the sample target area of the test strip. D. While keeping a finger over the hole of the capillary bulb, gently push down on the top of the bulb until the sample has been expelled onto the target area of the test strip. E. The entire target area of the test strip must be completely filled. F. The sample must be applied to the test strip within 15 seconds of lancing the fingertip. Testing Sample A. When the blood enters the testing area of the strip, the monitor enters the testing mode. Do not add more blood or touch the test strip during testing. The strip should not be disturbed until the monitor displays the INR results. B. Record the results and remove the test strip. C. The monitor stores the INR value in memory, along with the date and time the test was performed. D. Carefully discard lancet, capillary tube and the used test strip properly, according to infection control guidelines. Procedure Notes 1. The provider must determine the best INR level depending on the reason for anticoagulant treatment and how each individual responds to treatment. Each provider should establish expected values for his or her patient population or individual patients. 2. In the field of anticoagulant testing, variations in reaction mixture composition, thromboplastin tissue type, and system sensitivity may cause some variation in results when comparing results from different laboratory methodologies on the same patient. 3. The blood drop must be a minimum of 10 microliters in volume. Low sample volume will cause an error message. 4. This test measures INR results in persons on warfarin-type (Coumadin ) therapy. This test should not be used to monitor persons on heparin therapy. In vitro studies showed the CoaguChek Systems Tests are sensitive to levels of heparin over 0.15 U/mL. 5. When a patient is on intravenous infusion therapy, do not collect sample from arm receiving infusion line. Page 2 of 5 12/04

3 6. Hematocrit ranges between 32% to 52% do not significantly affect test results. 7. No interference was found in lipemic samples containing up to 500 mg/dl of triglycerides. Testing performed with in vitro-spiked samples indicated bilirubin up to 20 mg/dl and hemolysis up to 500 mg/dl did not significantly affect test results. Sources of Error If problems occur when performing tests, check the following: The wrong code chip was used. The first three numbers after the lot symbol on the test strip pouch should match the numbers on the test strip code chip. The test results may be affected by hematocrit values outside the range 32% to 52%. In rare cases, patients with long clotting times (INR >8) may produce a test error, as indicated by ERROR and a flashing test strip icon. If test error persists, results must be confirmed with an alternative test method. Contact the patient s physician. Incorrect storage of test strips. Test strip was moved between application and display of results. Test strip was double dosed. Dirty test strip guides and/or doors. Quality Control Quality control testing ensures the user s technique, integrity of the test strips, and performance of the monitor and strips together. Daily Requirements Two levels of Electronic Quality Control (EQC) must be tested and logged to verify proper monitor performance. These results are logged on the attached CoaguChek System Quality Control Log. Weekly Requirements Two levels of liquid quality control must be tested and logged to verify proper monitor performance. These results are logged on the attached CoaguChek System Quality Control Log. Additional Requirements Two levels of liquid controls must be tested and results must be within the designated range for the following situations: Opening a new box of test strips Suspected improper storage or handling of the strips Patient INR test results are unusually high or low (outside of target range) Two levels of electronic quality control or two levels of liquid quality control must be tested if the monitor is dropped or mishandled. Results must be within the designated range. Results/Interpretation The CoaguChek System monitor displays test results in units equivalent to laboratory plasma measurements. Results may be displayed in the International Normalized Ratio (INR = [PT/Mean Normal PT] ISI ), prothrombin time (PT) seconds, and/or as a ratio relative to normal (PT/Median Normal PT). Reference Range Page 3 of 5 12/04

4 PT seconds INR Critical value INR > 5.0 Alternative Method An alternative method is to check the INR using venous blood draw in the laboratory. Page 4 of 5 12/04

5 CoaguChek System Quality Control Log Liquid quality control testing 1. Weekly (same day each week) 2. Upon opening a new box of test strips 3. With suspected improper storage or handling of strips 4. When patient INR results are unusually high or low Electronic quality control testing 1. Daily Date Control 1 Lot # Liquid Controls Control 1 Results Control 2 Lot # Control 2 Results Electronic Controls Results of Results of Control 1 Control 2 Operator initials Expected ranges for liquid controls Expected ranges for electronic controls Level # Lot # Expected range Level # 1 Level # 2 Page 5 of 5 12/04