CLINICAL LAB SCIENEC

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ESSENTIALS OF CLINICAL LABORATORY SCIENCE
In the Lab
Determining the Maximum Packed Cell Volume
Before beginning the Hct, determine the maximum packed cell volume by following
these steps:
1. Use two different samples, one with an Hct of greater than 50%.
2. Prepare two Hct tubes per sample and centrifuge for 2 minutes.
3. Read and record results.
4. Prepare two more Hct tubes per sample and centrifuge for 2.5 minutes.
5. Read and record results.
6. Repeat this procedure, increasing the time by 30-second intervals, until the Hct
reading remains the same for two consecutive time periods. Use this time for routine
testing.
7. Once per shift, run a duplicate analysis on the microHct and use another analytical
procedure for obtaining a microhematocrit.
8. Record your results. The results should be within ±2%. If your results are outside
of these limits, repeat with a second sample.
9. If the second analysis is beyond the limits, notify your supervisor, as recalibration
of the microhematocrit centrifuge or other centrifuge may be required.
Equipment and Supplies
1. Gloves, disposable paper towels, and disinfectant or other cleaning solution
2. Report form for Procedure #3
3. Sealing putty (Critoseal)
4. Clinical centrifuge fitted with Hct head
5. Microcapillary reader
6. Anticoagulated blood sample and plain hematocrit tubes (if using a supplied sample).
7. If the procedure will include collection of the sample through finger stick and
capillary tube, the following supplies will also be needed:
Alcohol prep pad
Cotton balls or 2 2 gauze pads
Sterile lancets (or Autolet device)
Heparinized hematocrit tubes
8. Disinfectant for cleaning work surfaces following procedure
9. Sharps container for disposal of lancets and slides, and other appropriate waste
disposal containers
Procedure
1. Wash hands and don gloves.
2. Assemble necessary equipment and supplies, arranging them in a systematic
manner where each item may be easily reached. For a microhematocrit, it is
simple to lay out necessary supplies in a small area.
3. If an anticoagulated blood sample is available, use it to fill a plain capillary tube
(Figure 13-10A), then proceed to step #10. If you will be performing a finger
“stick” to obtain the sample, follow steps # 4 through #9 below.
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