Comprehensive Guide to Eldon Card Blood Typing and Hematocrit Procedures

Preparation of Eldon Sticks:
- Before beginning the procedure, separate the provided Eldon sticks into four individual units.
Documentation:
- Write all necessary personal data on the Eldon card before it becomes contaminated or wet.
Reagent Verification:
- Verify that all four reagent spots are present and correctly colored:
  - Green
  - Red
  - Yellow
  - Blue

Water Application:
- Apply exactly one drop of water directly onto each of the four colored reagent circles.
- Use a pipette/dropper to apply the water.
- Crucial Safety/Accuracy Note: Do not touch the colored reagent spots with the tip of the pipette to avoid cross-contamination.
- Ensure water does not mix between the circles; each circle must remain isolated.

Lancet Preparation:
- Twist the colored tip of the safety lancet and pull it off to expose the mechanism.
- The lancet is a one-time use, self-retractable device. Once pressed against the skin, a spring-loaded blade pops out and immediately retracts, rendering the device unusable for a second attempt.
Finger Preparation:
- Sterilization: Clean the target finger with a sterile alcohol swab.
- Increasing Blood Flow:
  - Swing the arm to use centrifugal force to move blood toward the fingertips.
  - Rub hands together or perform exercise to ensure hands are warm and pinkish, rather than cold and pale.
  - Friction from wearing gloves can also help warm the hands.
- Site Selection: Puncture the soft skin on the side of the fingertip rather than the pad (front).
  - The side has more accessible blood vessels and fewer calluses.
  - It is less painful during daily activities afterward (e.g., using a phone or doorknob).
Puncture Technique:
- Place the finger firmly on the table to prevent the "runaway" reflex (pulling the hand away).
- Press the lancet down firmly and hold for approximately one second to ensure a deep enough puncture.
Collecting the Sample:
- Massage (or "milk") the entire finger towards the tip to encourage a large drop of blood.
- Avoid squeezing directly at the puncture site.
- Gravity can be utilized by standing up and holding the hand below the level of the heart.

Transferring Blood:
- Use an Eldon stick to collect a large drop of blood.
- Place the stick with the blood in the center of a reagent circle so it touches the previously applied water.
- Use a brand new stick for each of the four circles to prevent cross-contamination.
Mixing:
- Stir each circle with its specific stick for approximately ten seconds.
- Ensure the mixture of blood, water, and reagent is spread carefully across the entire area of the reagent circle.
Tilting and Agitation:
- Tilt the card to an almost upright position (approximately a $45^{\circ}$ angle).
- Hold the card at each angle for ten seconds to allow the reaction to flow.
- Note: The Rh (Rhesus) reaction is often slower than the A and B reactions; do not stop the process prematurely.

Agglutination: Look for the clumping of red blood cells (agglutination), which indicates a positive reaction for 그 antigen.
The Control Circle: The final circle (usually the far right) serves as a control to ensure the technique worked correctly and that the blood does not clump spontaneously without reagents.
Timing: Read the results before the card dries completely.
Preservation:
- Once the card is completely dry, an Eldon foil (laminating sheet) can be applied to protect the results.
- Never apply the foil while the blood is still wet.

Collection:
- Use a clear plastic capillary tube to collect blood via capillary action.
- Hold the tube horizontally to prevent blood from flowing out.
- Aim to fill the tube at least two-thirds ( $\frac{2}{3}$ ) to three-quarters ( $\frac{3}{4}$ ) full.
Sealing:
- Seal one end of the tube by pressing it into a tray of sealing clay.
- To avoid snapping the glass or plastic, hold the tube very close to the end being pressed into the clay.
Centrifugation:
- Tubes are placed in a micro-hematocrit centrifuge.
- Each slot is numbered; students must remember their assigned number to retrieve their specific sample.
Measurement and Calculation:
- Use a ruler to measure the layers of the spun blood.
- Disregard the clay: When measuring, the white clay plug is not part of the blood sample.
- Measure the "formed elements" (red blood cells) at the bottom and the "straw-colored" plasma at the top.

Workstation Set-up:
- Lay out paper towels to define a "zone," though towels are for organization and will not stop a major soak-through.
Sharps Disposal: The following high-risk items must be placed in a puncture-proof Sharps Container:
- Used lancets
- Used Eldon sticks
- Used capillary tubes
General Biohazard Waste:
- Paper towels, alcohol swabs, and gloves contaminated with blood go into a biohazard bag.
Glove Removal Technique:
- Wad up contaminated paper waste in the palm of a gloved hand.
- Peel the glove off inside-out so the waste is trapped inside the glove, then dispose of it.
Fainting Protocols:
- If feeling faint, stay seated. It is a shorter distance to the floor from a seated position than standing.
- Communicate with lab partners if feeling unwell (cold sweats, nausea).