Phlebotomy Techniques and Order of Draw

Introduction to Blood Collection Techniques

  • The process of drawing blood is practiced under strict guidelines to ensure accuracy and minimize trauma to patients.

Principles of Inversion in Blood Collection

  • Purpose of Inversion: To mix additives within blood tubes with the drawn specimen.

    • Inversion is not wasteful; it is crucial for proper mixing of additives.

    • Use gentle inversion rather than vigorous shaking to avoid hemolysis of red blood cells.

  • Inversion Technique: 5 to 10 gentle inversions are recommended to mix additives effectively.

    • Full inversion defined as rocking motion rather than flipping to avoid cell breakage.

  • Additives and their Impact on Blood Clotting:

    • Anticoagulants prevent blood from clotting; tubes with such additives should remain vertical.

    • Tubes with clotting factors must stand upright to facilitate proper clumping and separation of red blood cells.

Additives in Blood Collection Tubes

  • Types of Additives:

    • EDTA (Ethylene Diamine Tetraacetic Acid): Commonly used in purple top tubes; prevents clotting by chelating calcium.

    • Citrate: Found in light blue tubes, also chelates calcium; used for coagulation studies, must be filled accurately in a 9:1 ratio with blood.

    • Oxalates and Heparin: Other anticoagulants found in specific tubes.

  • Additive Impact on Results: Each type of additive can influence hematological results, and students must recognize the implications of incorrect tube selection.

    • Common practice involves validating the order of draw to maintain specimen integrity and avoid cross-contamination.

Order of Draw

  • Importance of Order: Minimizes cross-contamination of additives between tubes.

  • Standard Order:

    • Blood Culture

    • Light Blue (Sodium Citrate)

    • Red (Serum) and Gold/SST (Serum Separator Tube)

    • Green (Heparin with/without gel)

    • Lavender/Purple (EDTA)

    • Gray (Potassium Oxalate/Sodium Fluoride)

    • ACD tubes are often drawn at the end.

  • Incorrect order can lead to falsely elevated potassium levels and errors in coagulation studies.

Preparation for Blood Collection

  • Patient Identification: Confirm patient's full name, date of birth, and other identifiers by having them spell their name. Ensure no confusion occurs, especially in cases of common names or look-alikes.

  • Requisition Protocols:

    • Proper requisition forms must accompany blood draws, signed or electronically validated by a licensed physician.

  • Environmental Considerations:

    • Secure adequate space for wheelchair patients and ensure all patients’ conditions are suitable for blood draws before proceeding.

Venipuncture Technique

  • Venipuncture Procedure Steps:

    1. Patient Positioning: Ensure comfortable positioning (typically seated, or reclined in case of vulnerability).

    2. Tourniquet Application: Should be applied 3-4 inches above the draw site; avoid excessive tightness to prevent collapsing veins.

    3. Fist Clenching and Calming Techniques: Patients should make a fist but not pump to prevent elevated potassium levels.

    4. Site Disinfection: Use an alcohol swab while allowing air drying fully.

    5. Needle Selection: Choose appropriate gauge (21 is preferred for most samples) based on vein size and patient comfort.

    • Avoid premature setup of needles before vein identification.

    1. Engaging the Vein: Insert needle at a correct angle (15-30 degrees for arms, and 10-15 for hands).

    2. Blood Collection: After blood begins to flow, appropriately fill designated tubes in the correct order.

Post-Procedure Steps

  • Post-Draw Care:

    • Ask the patient to hold pressure on the draw site for recommended duration (1-3 minutes for standard patients; up to 5 minutes for those on blood thinners).

    • Label specimens accurately after confirming patient identification again before submitting to labs.

    • Register and document the collection accurately in desired formats.

Special Considerations for Pediatric and Geriatric Patients

  • Challenges with Pediatric Patients:

    • Use of smaller gauge needles (23-25 in infants); require gentler techniques and often must involve parents during the draw for reassurance.

    • Informing children and their guardians about the procedure without inducing fear is vital.

  • Geriatric Patient Protocols:

    • Offer extra care due to fragile skin and potential sensitivities; slow and clear communication is essential.

    • Monitor closely for pain tolerance and bleeding; adjust techniques as necessary to avoid complications.

Conclusion

  • Continuous Improvement: Adopting a mindset of accountability and attention to patient care can promote high quality in blood collection procedures.

  • Ethical and Practical Implications: All staff must work within established guidelines and remain adaptable to individual patient needs, promoting compassion and care throughout the blood draw process.