Puncturing the Skin to Obtain Capillary Blood Health Science Technology II Unit 18:3

Venipuncture When larger quantities of blood are needed Blood is taken from the _________.

Cleanse the skin 70% isopropyl alcohol

Common puncture sites Fingers Heels (usually infants) Earlobes

Finger Avoid thumb, index finger, pinkie Avoid calluses, scars, rashes, sores, etc. 2-4 mm deep Puncture should be made across the grain of lines

Heels Use plantar & lateral aspects of heel No deeper than 2 mm

Sterile Lancet

First drop of blood Always remove 1st drop with sterile gauze Do not squeeze or milk out blood

After collection Have patient hold sterile gauze over the site until bleeding stops Stay with patient until bleeding stops

Performing a Microhematocrit Unit 18:4

Hematocrit HCT, crit Packed Cell Volume, PCV Measures the volume of RBCs as a percentage of blood Normals: Women: 35-45 % Men: 45-55 %

Centrifuge Spins blood at approximately 10.000 revolutions per minute

Microhematocrit Capillary Tubes Usually lined with an anticoagulant, such as heparin

Hold capillary tube at a slight angle to skin Do not touch skin Place end without indicator mark into the drop of blood Allow blood to flow until it reaches mark

Seal Tube Hold gloved finger over the end of tube Seal opposite end (end without blood) with sealing clay Avoid contaminating clay block with blood

Spin the Tubes Place capillary tube in centrifuge with clay seal against the rubber buffer Usually spin tubes 3-5 minutes

Reading Line the top of the clay with zero Read number at the top of the RBC layer

Measuring Hemoglobin Unit 18:5

Hemoglobin (Hgb) Composed of 2 parts: Heme: contains iron Globin: protein

Hemolysis Destruction of RBCs Must be done in order to release hemoglobin from RBCs so it can be measured

Hemoglobinometer Measures the hemoglobin concentration in blood Using color comparison, approximate reading is obtained Relies on human eye for color match

Automated photometer Cuvette filled with hemolyzing solution Color intensity measured automatically

Counting Blood Cells Unit 18:6

Hemacytometer Counting chamber in a calibrated slide with a grid for counting cells 9 large primary squares

Counting Leukocytes Use 4 primary corner squares (contain 16 smaller squares Only cells that touch the left line or top each of the large squares are counted

Leukocyte Formula Add the numbers on the 4 corners on each side of the slide Get an average of these 2 totals Multiply the average by 50 (if 1:20 dilution)

Counting Erythrocytes Center square is used Center square is divided in to 25 secondary squares Count in the 4 corner squares & center square of the secondary squares

Erythrocyte Formula Obtain the average of the total count of the 5 squares on each side of the slide Multiply by 10,000

Dilution of Sample Blood sample must be diluted Different solutions are used to dilute for a WBC count vs. RBC count

Preparing & Staining a Blood Smear Unit 18:7

Blood Smear Differential count: 100 WBCs are counted, determine percentage of each type of WBC present Examine form, structure & relative number of all types of blood cells

Stain Stain smear with Wright’s stain or 3 step quick stain Examine smear at the feathered edge