Procedure

Procedure

WHOLE BLOOD GLUCOSE TESTING USING THE ACCUCHEK HQ

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Pathology Department

Nursing Units

Endocrine Clinic

IPU

Emergency Department

Day Hospital

PACU/ASU

PRECAUTION: WHILE PERFORMING THIS PROCEDURE, THE FOLLOWING

SAFETY MEASURES MUST BE TAKEN: GLOVES MUST BE WORN; SMOKING, EATING, DRINKING, APPLICATION OF COSMETICS, AND MANIPULATION OF CONTACT LENSES ARE PROHIBITED IN ALL TECHNICAL WORK AREAS. REFER TO THE UNIVERSAL PRECAUTIONS POLICIES.

Complexity: Waived-Definitive

I. Principle

Blood glucose determinations are used most commonly in the diagnosis and treatment of diabetes mellitus, but are also useful in the diagnosis of hypoglycemia. In the newborn, blood glucose values are useful in the detection of hypoglycemia, a common condition, especially in the premature, and a potential cause of brain damage and even death in these infants. Here at Children’s Memorial Hospital, we use the Accuchek Advantage to monitor patients for hypoglycemia and to monitor the treatment of patients with diabetes.

The Accu-Chek Advantage Blood Glucose Monitor is a battery-operated monitor which measures the amount of glucose in whole blood. It is used with Advantage Comfort Curve Test Strips. The test strip employs the electrochemical principle of biamperometry. The monitor applies a voltage between two identical electrodes, which causes the reduced mediator formed during the incubation period to be converted to an oxidized mediator. This generates a small current that is read by the monitor. The result is displayed after 40 seconds of blood application.

When the blood is placed on the test strip, the enzyme glucose dehydrogenase converts the glucose in the blood sample to gluconolactone. This reaction liberates an electron that reacts with a coenzyme electron acceptor, the oxidized form of the mediator hexacyanoferrate, forming the reduced form of the mediator, hexacyanoferrate. The AccuChek Advantage monitor is calibrated using the glucose hexokinase reference.

II. Reagents and Supplies

AccuData HQ

Advantage Comfort Curve Reagent Strips:

Store: Room temperature. Good until expiration date on the vial. Protect from excessive heat, humidity or frozen temperatures. Replace the vial cap immediately after taking out a test strip. Label vial with opened date. A strip removed from the vial must be used within 5 minutes.

Advantage Code Key bearing the same 3-digit code number as the package of test strips in use

Lancing device

Alcohol wipes (optional)

Bandaids (optional)

Disposable latex gloves

Two 3 volt Lithium batteries

Meter Cradle

III. Specimen

Prior to collecting the patient’s sample, the patient’s identity must be verified by looking at the arm band. One drop of capillary, venous, neonatal (including cord blood), and arterial whole blood specimens may be used. Capillary samples must be tested immediately after collection. For best results with arterial or venous blood, the following anticoagulants/preservatives are recommended: heparin, citrate, sodium fluoride/potassium oxalate, sodium fluoride, maleimide in lithium heparin, and potassium oxalate. EDTA should not be used as a preservative. Caution should be taken to clear arterial lines before blood is drawn. For Specimen Collection, refer to the nursing policies.

IV. Testing Procedure

The GTS will store the following information about each patient test:

Test Result, Operator ID, Patient ID, Test Strip Code Information, Test Time and Date, and Comment Code

Prior to obtaining a patient sample, verify patient’s identification as per nursing policies.

1. Turn monitor on by pressing the ON/OFF Button on the lower left corner of the touchscreen.

2. At the Operator Identification Screen, enter your four digit Operator ID# (this is the last four digits of your social security number) and hit NEXT.

3. Press PAT at the Task Selection Screen to run a patient test (press CNTRL if running a control)

4. Enter the appropriate 6 digit patient medical record number and hit NEXT. If patient does not have a medical record number, enter patient’s name by pressing the ABC key to select the alpha option and enter as much of the patient’s last name and first initial as you can. There is a limit of 6 digits.

5. Verify the strip code by comparing the test strip code on the reagent vial to the code displayed on the screen. Press YES if correct.

6. At this time the meter will be turned on automatically and can be removed from cradle at this time.

7. Remove the test strip recapping vial immediately and insert the test strip properly when display flashes the strip icon.

8. Properly obtain blood sample. Capillary, venous, and arterial specimens are acceptable.

9. Fill the test strip by touching and holding the drop of blood to the edge of the yellow window, allowing blood to be pulled into the strip when the flashing drop icon appears. The yellow window must be full. If the drop was not large enough, more blood may be added within 15 seconds.

10. When the testing is complete, the meter will beep and the result will be displayed on the touchscreen. At this point, place the meter back onto its cradle.

11. Enter the appropriate comment code by pressing it and hitting NEXT.

12. Remove test strip from the meter and turn the meter off if you are done testing.

13. Properly document the result in the patient chart.

Note: If HI or LO appears on the screen, it indicates values greater than 600 mg/dl or less than 10 mg/dl respectively. Repeat the test. Glucose results less than 40 mg/dL or greater than 500 mg/dL must be called to the ordering physician to determine whether laboratory confirmation is necessary. Document all actions taken on the unit based record. If the monitor result contradicts your clinical impression, perform a quality control test to determine the problem.

V. Quality Control

Glucose Control Solutions:

AccuChek Advantage control solutions: Level 1 (LO) and Level 2 (HI).

Store: At room temperature (18-32⁰C) before and after opening. Do not refrigerate. Unopened vials are stable at room temperature until the manufacturers expiration date. Opened vials are stable at room temperature for three months or until manufacturers expiration date, whichever comes first.

Label the QC vial with the date that the vial was opened.

These quality control samples are used to check the accuracy and reliability of the Advantage System and monitors both operator technique and function of the meter. Test these solutions the same way as a drop of blood.

Frequency:

Level 1 and 2 should be run every 24 hours of patient testing and when the “RUN CONTROLS” prompt is displayed on the GTS. This will be performed by a certified operator. All operators must be introduced on operation by designated unit "Trainers" or Medical Technologist, using specific guidelines in the AccuCheck HQ Operator's Manual (refer to Skills Checklist).

Special situations which also require QC include:

1. After changing monitor batteries or recoding the monitor for any reason.

2. If monitor is dropped.

3. If the cap to the vial of test strips has been left off, or the vial has been exposed to excessive heat, humidity, or cold.

4. Any time the glucose result contradicts your clinical impression.

5. Whenever a new lot number of test strips is opened.

Testing Procedure:

1. Turn monitor on by pressing the ON/OFF Button on the lower left corner of the touchscreen.

2. At the Operator Identification Screen, enter your four digit Operator ID# (this is the last four digits of your social security number) and hit NEXT.

3. Press CNTRL at the Task Selection Screen to run a control solution.

4. Select the level of control that you want to run.

5. Verify solution lot # by comparing the lot number on the control vial to the lot # displayed on the screen. Press YES if correct.

6. Verify the strip code by comparing the test strip code on the reagent vial to the code displayed on the screen. Press YES if correct.

7. At this time the meter will be turned on automatically and can be removed from cradle at this time.

8. Remove the test strip recapping vial immediately and insert the test strip properly when display flashes the strip icon.

9. Fill the test strip by touching and holding the control vial to the edge of the yellow window, allowing the solution to be pulled into the strip when the flashing drop icon appears. The yellow window must be full. If the drop was not large enough, more solution may be added within 15 seconds.

10. When the testing is complete, the meter will beep and the result will be displayed on the touchscreen. At this point, place the meter back onto its cradle.

11. Enter the appropriate comment code by pressing it and hitting NEXT.

12. Remove test strip from the meter and turn the meter off if you are done testing.

Out-Of-Range QC Documentation and Troubleshooting:

The AccuChek Advantage cannot be used for patient testing if a QC result is outside the expected range. Until both QC results are within range, the instrument will not let you run a patient test. If a QC result is out of range, the AccuChek HQ will display "Result Out of Range"

If a QC result is outside the expected range, the following troubleshooting steps should be taken:

1. Check expiration date of strips and control solutions. Discard outdated reagents.

2. Compare the 3-digit code numbers on strip vial and the screen to ensure an identical match.

3. Review proper technique.

4. Repeat QC. If it is still out of range, go to step 5.

5. Open a new vial of test strips Repeat QC. If QC is within range, discard the vial of strips that yielded out of range results. If QC is still out of range, go to step 6.

6. Open a new vial of QC material. Date vial with opened date. Repeat QC. If QC is within range, discard the QC vial that yielded out of range results. If QC is still out of range, go to step 7.

7. The meter should not be used. Put a note on the meter stating that it is "out of order" to be sure that no one else uses it. Page the Medical Technologist from the Pathology department (4431) or call at ext. 4431. The Blood Bank has loaner meters available for use when a meter is out-of-service. When the Medical Technologist is unavailable call AccuChek Technical Support at 1-800-440-3638.

Document all corrective actions taken using the appropriate comment codes

VI. As Needed Maintenance

A. Clean the surface of the GTS with a soft cloth slightly dampened with a freshly mixed solution of 1:10 5% hypochlorite (Clorox or equivalent) in water or 70% isopropyl alcohol, full strength.

B. Check that the AccuChek meter screen illuminates. If it does not, the battery pack may need to be charged. If the battery pack needs to be charged, a battery sign will illuminate at the top right hand side of the screen.

To charge the battery pack, place the meter in it’s gray meter cradle.

C. If the batteries are low on the hand held monitor, the lower left corner of the monitor will display a picture of a battery. Open the battery cover on the bottom side of the hand held monitor and change both 3V lithium batteries. Be sure to replace the batteries one at a time. DO NOT LET THE BATTERIES TOUCH EACH OTHER. Lithium batteries are provided by central supply.

D. Stock necessary supplies (ie, strips, lancet caps, alcohol wipes). All items (except the quality control solution vials) are provided by central supply.

E. If there is no response between the meter and the hand held monitor:

§ Verify that the serial number on the back of the Advantage matches the serial number on the GTS.

§ Clean the infrared communication windows on both the GTS and the back side of the Advantage with an alcohol pad.

VII. Patient Results

All results are recorded in the patient’s chart.

Expected results: Neonates 33 - 99 mg/dl

Normal fasting child/adult 60 - 110 mg/dl

The following protocol is recommended for reporting whole blood glucose results from bedside glucose meters:

Whole blood glucose results below 40 mg/dl will be reported as <40 mg/dl. Whole blood glucose levels above 500 mg/dl will be reported as >500 mg/dl. Critical values are up to the assessment of the physician based on patient history and clinical condition.

The ordering physician should be notified of critical whole blood glucose results to determine whether laboratory confirmation is necessary.

VIII. Limitations of Procedure

§ System measurement range is 10-600 mg/dl.

§ Venous and arterial samples should be performed within 30 minutes of specimen collection to avoid glycolysis.

§ Avoid air bubbles on test strip.

§ Do not use EDTA (lavender tube) as a preservative.

§ Caution should be taken to clear (backflush) arterial lines before blood is drawn. Never draw from a line that is infusing glucose.

§ Do not use during xylose absorption testing.

§ In vitro Bilirubin (unconjugated) up to 20 mg/dl and in vitro lipemic samples up to 5000 mg/dl have no interfering effect.

§ Uric Acid concentrations >10 mg/dl in hypoglycemic patients (blood sugars < 70 mg/dl), and uric acid >16 mg/dl in euglycemic and hyperglycemic patients (blood sugars > 70 mg/dl), may give falsely elevated results versus a whole blood reference.

§ At glucose concentrations above 200 mg/dl, low hematocrits (<25%) may cause elevated glucose results.

§ At glucose concentrations above 200 mg/dl, elevated hematocrits >55% may cause reduced glucose results.

§ Caution is advised for the interpretation of neonate glucose values below 50 mg/dl.

In situations of decreased peripheral blood flow, fingerstick blood glucose testing may not be appropriate as it may not reflect the true physiological state. Examples would include but are not limited to: severe dehydration caused by diabetic ketoacidosis or the hyperglycemic nonketotic state, hypotension, shock, or peripheral vascular disease.