ARTERIAL PUNCTURE

• Arterial puncture


  Used to collect blood specimen for arterial blood gas (ABG) analysis to manage cardiopulmonary disorders and maintain the acid-base balance of the body
• Arterial blood


  • Ideal specimen for the respiratory function evaluation due to the consistency of its composition and high oxygen content
• Personnel who collect arterial specimen


  • Nurses
  • Medical technologists & technicians
  • Respiratory therapists
  • Emergency medical technicians
  • Level II phlebotomists
• Purpose of collecting arterial blood gas (ABG) specimens


  To diagnose respiratory disorders by evaluating oxygenation, ventilation, and acid-base balance
• Accuracy of ABG results is easily affected by preanalytical error, so proper assessment of the patient and collection and handling procedures should be strictly followed
• Commonly Measured ABG Analytes


  • pH
  • PaO₂
  • PaCO₂
  • HCO₃
  • O₂ saturation
  • Base excess
• pH


  A measure of acidity or alkalinity of blood (acidosis or alkalosis)
• PaO₂


  Partial pressure of O₂ dissolved in arterial blood
• PaCO₂


  Partial pressure of CO₂ dissolved in arterial blood
• HCO₃


  A measure of bicarbonate in blood
• O₂ saturation


  Percent O₂ bound to hemoglobin
• Base excess


  A calculation of non respiratory part of acid-base balance
• Criteria for selecting arterial puncture site


  • Collateral circulation
  • Artery accessibility and size
  • Low risk of surrounding tissue injury
  • Free from inflammation, irritation, edema, hematoma, lesion, and wound
  • No AV shunt or recent arterial puncture
• Radial artery


  • Most commonly used site, good collateral circulation, easy to palpate, less chance of hematoma formation
• Brachial artery


  • Adequate collateral circulation, sometimes preferred for large volume blood, deeper and harder to palpate, risk of puncturing nearby vein or nerve
• Femoral artery


  • Large and easily palpated, sometimes only site possible, poor collateral circulation, increased risk of infection and hematoma
• Equipment and supplies needed for arterial puncture


  • Antiseptic
  • Local anesthetic (optional)
  • Short-bevel hypodermic needle with safety feature
  • to 5-mL self-filling syringe
  • Luer-tip cap
  • Coolant (when applicable)
  • Gauze squares
  • Self-adhering gauze bandage
  • Identification and labeling materials
  • Sharps container
• Required and supplemental requisition information


  • Current body temperature
  • Respiratory rate
  • Ventilation status
  • Fraction of inspired oxygen (FIO₂)
  • Prescribed flow rate
• Patient Assessment and preparation procedures

  1. Identification and explanation of procedures

  2. Patient preparation and assessment

  3. Steady state

  4. Modified Allen test

  5. Administration of Local Anesthetic (optional)
• Modified Allen test


  Procedure to determine if patient has collateral circulation before arterial puncture
• Collecting radial blood gases


  1. Review accession test request

  2. Approach and identify patient, explain procedure

  3. Assess patient steady state, verify collection requirements

  4. Observe hand hygiene, wear gloves

  5. Verify collateral circulation

  6. Position arm, locate radial artery, clean site

  7. Administer local anesthetic if ordered

  8. Assemble ABG equipment, clean gloved finger

  9. Relocate radial artery, warn patient, insert needle

  10. Fill syringe, remove needle, apply pressure

  11. Remove and discard needle, expel air bubbles, label specimen

  12. Check patient's arm, dispose materials, remove gloves

  13. Transport specimen to lab immediately
• Arterial puncture is an invasive procedure with associated hazards and complications, proper technique is followed to avoid complications but some cannot be avoided
• Arterial puncture procedure


  1. Expel air bubbles

  2. Cap the syringe and mix thoroughly

  3. Label the specimen

  4. Check patient's arm for swelling or bruising

  5. Apply a pressure bandage

  6. Dispose used and contaminated materials properly

  7. Remove the gloves and sanitize hands

  8. Thank the patient courteously

  9. Transport the specimen to the laboratory immediately
• Hazards and complications of arterial puncture
• Hazards and complications of arterial puncture


  • Arteriospasm
  • Artery damage
  • Discomfort
  • Infection
  • Hematoma
  • Numbness
  • Thrombus formation
  • Vasovagal response
• Sampling errors that may affect the integrity of an arterial sample


  • Air bubbles not expelled
  • Processing exceeded optimal time
  • Sample not mixed properly
  • Use of improper syringe
  • Obtaining venous blood by mistake
  • Improper anticoagulant used
  • Improper volume of heparin used
• Criteria for rejection of ABG specimen


  • Air bubbles found
  • Specimen has clotted
  • Hemolysis of the specimen
  • Did not comply with labeling requirement
  • Prescribed transportation temperature not met
  • Specimen did not meet required volume
  • Took too long to reach laboratory
  • Incorrect syringe type used
• Approximately 48% to 68% of laboratory result failures are due to prior to analysis phase mishandling or error
• Routine handling of specimens


  1. Adhere to time limits for delivery

  2. Mixing tubes by inversion

  3. Transporting specimens with stopper on
• Special handling of specimens


  1. Transport at near body temperature (37°C)

  2. Pre-warm tubes at 37°C

  3. Use portable heat blocks during transport

  4. Use heel warmer for specimens that can withstand higher than 37°C
• Examples of specimens that require special handling


  • Cold agglutinin
  • Cryofibrinogen
  • Cryoglobulins
• Examples of chilled specimens


  • ACTH
  • Acetone
  • ACE
  • Ammonia
  • Catecholamines
  • Free fatty acids
  • Gastrin
  • Glucagon
  • Homocysteine
  • Lactic acid
  • PTH
  • pH/blood gas
  • Pyruvate
  • Renin
• Light-sensitive specimens should be wrapped in aluminum foil or stored in light-blocking amber-colored containers
• Examples of light-sensitive specimens


  • Bilirubin
  • Carotene
  • Red cell folate
  • Serum folate
  • Vitamin B2
  • Vitamin B6
  • Vitamin B12
  • Vitamin C
  • Urine porphyrins
  • Urine porphobilinogen
• Criteria for specimen rejection


  • Not properly identified
  • Inadequate volume
  • Hemolysis
  • Wrong tube used
  • Outdated tube
  • Improper handling
  • Contaminated
  • Insufficient specimen
  • Incorrect collection time
  • Exposed to light
  • Did not follow testing time limits
  • Delay or error in processing
• Time constraints and exceptions for delivery and processing of specimens

  1. Routine blood specimen should reach lab within 45 minutes

  2. Specimen needing centrifugation should be done within 1 hour

  3. EDTA specimens should not be centrifuged

  4. STAT/emergency specimens take priority

  5. Exceptions for time limits: blood smear, CBC, ESR, reticulocyte, glucose, PT
• OSHA-required protective equipment for processing specimens in the lab includes gloves, lab gown/coat, and masks
• Centrifugation of specimens


  1. Leave stoppers on to avoid contamination

  2. Balance tubes of same size and volume

  3. Do not repeat centrifugation

  4. Centrifuge plasma specimens immediately

  5. Allow serum specimens to fully clot before centrifugation

  6. Remove stoppers carefully with gauze/tissue to catch drops/aerosols
• Aliquot


  A portion of a sample specimen taken for analysis or testing
• Aliquot preparation


  1. Transfer portion of specimen into labeled tubes using disposable pipettes

  2. Do not mix specimens with different anticoagulants

  3. Cover tubes immediately after filling