Module 8

• Introduction

  • Arterial blood is collected to determine the level of oxygen and carbon dioxide in the blood and measure the pH.

  • Arterial collection is more dangerous than venous collection to the patient and it requires in-depth training beyond routine phlebotomy skills.

  • It is usually performed by physicians, nurses, medical laboratory scientists (MLSs), medical laboratory technicians (MLTs), or respiratory therapists (RTs).
• Testing of ABGs measures the ability of the lungs to provide oxygen (O2) to the blood and to remove carbon dioxide (CO2) from the blood and exhale it.

  Conditions that requires ABG testing:

  • Respiratory or metabolic origin and include chronic obstructive pulmonary disease (COPD)
  • Cardiac and respiratory failures
  • Severe shock
  • Lung cancer
  • Diabetic coma
  • Open heart surgery
  • Respiratory distress syndrome (RDS) in premature infants
• Measures the pressure of O2 dissolved in the blood. Tells how well O2, moves from the lungs into the blood?

  Partial Pressure of Oxygen PO2
• Measures the pressure of CO2, dissolved in the blood. Tells how well CO2, moves out of the lungs?

  Partial Pressure of Carbon Dioxide PCO2
• Measures the acidity or alkalinity of the blood.

  Indicates acidosis or alkalosis.?

  pH
• Buffers the blood to prevent acidosis or alkalosis.?

  Bicarbonate HCO3
• Measures the amount of O2, in the blood?

  Oxygen Content CTO2
• A decrease in pH indicates an increase in hydrogen ion concentration; this condition is called acidosis. An increase in pH indicates a decrease in hydrogen ion concentration; this condition is called alkalosis.
• It measures how much of the hemoglobin in the red blood cells is carrying O2?

  Oxygen Saturation O2Sat
• Normal Values for Arterial Blood Gas

  1. PO2 = 75 - 100 mmHg
  2. PCO2 = 35 - 45 mmHg
  3. pH = 7.35 - 7.45 mmHg
  4. HCO3 = 20 - 29 mEq/L
  5. CTO2 = 15 - 22 mL / 100 mL
  6. O2Sat = 95% - 100%
• Arterial Blood Collection Kits

  • Contain pre anticoagulated syringes with hypodermic needles containing a safety shield and a tightly fitting cap for the Luer tip of the syringe after the needle has been removed.
• What do you do when there is no Arterial Function Syringe Equipment?

  1. Use a solution of sodium heparin with a concentration of 1000 U/mL.
  2. Calculate the volume of heparin to draw up. Use 0.05 mL of heparin solution for each milliliter of blood to be drawn.
  3. Attach a 20 gauge needle to the syringe, and draw up the heparin by slowly pulling back on the plunger.
  4. Rotate the liquid in the syringe to coat the barrel.
  5. Remove the 20 gauge needle and replace it with the needle you will use for collection.
  6. Expel the excess heparin and any air by depressing the plunger fully with the needle pointed down.
• Antiseptic

  • Both alcohol and povidone iodine or chlorhexidine are used to clean the site.
  • The puncture site is cleansed with povidone iodine or chlorhexidine.
• Lidocaine Anesthetic

  • To lessen pain, 0.5 mL of lidocaine, a local anesthetic, may be injected subcutaneously, using a 25 to 26 gauge needle on a 1 mL syringe.
  • Note that not all hospitals use lidocaine before the puncture.
• Other Equipments

  • Crushed ice
  • Ice and water
  • Gauze pads
  • Pressure bandages
  • Thermometer (to take the patient’s temperature)
  • Transport container.
• Arterial Puncture Procedure Overview

  1. Phlebotomist Preparation
  2. Patient Assessment
  3. Steady State
  4. Site Selection
  5. Modified Allen Test
  6. Preparing the site
  7. Performing the Puncture
  8. Needle removal
  9. Completion of Procedure
• Is tourniquet needed in arterial blood collection?

  No
• It refers when a patient should have been receiving the specified amount of oxygen and have refrained from exercise?

  Steady State
• How many minutes is the patient required to refrain from exercising ?

  20 to 30
• • Site Selection

  To be acceptable as a puncture site, an artery must be

  1. Large enough to accept at least a 25 gauge needle
  2. Located near the skin surface so that deep puncture is not required
  3. In an area where injury to surrounding tissues will not be critical
  4. Located in an area where other arteries are present to supply blood (collateral circulation) in case the punctured artery is damaged.
• Site Selection

  • Radial artery - located on the thumb

  side of the wrist (site of choice)

  • Brachial artery - located near the basilic vein in the antecubital area
• • Physicians and specially trainedpersonnel must collect samples from sites such as the femoral artery, umbilical and scalp veins, and the foot artery (dorsalis pedis)
• What test is performed to determine if the ulnar artery is capable of providing collateral circulation to the hand?

  Modified Allen Test
• Step 1. Extend the patient’s wrist over a rolled towel and ask

  the patient to form a tight fist.
• Step 2. Locate the pulses of the radial and ulnar arteries on

  the palmar surface of the wrist by palpating with the second

  and third fingers, not the thumb, which has a pulse.
• Step 3. Compress both arteries.
• Step 4. Have the patient open the fist and observe that the

  palm has become pale (blanched).
• Step 5. Release pressure on the ulnar artery only and watch

  to see that color returns to the palm. This should occur within

  5 seconds if the ulnar artery is functioning.
• Step 6. If color does not appear (negative modified Allen

  test), the radial artery must not be used. If the modified Allen

  test is positive, proceed by palpating the radial artery to

  determine its depth, direction, and size.
• Performing the Puncture

  • The heparinized syringe is held like a dart in the dominant hand and the needle is inserted about 5 to 10 mm below the palpating finger at a 30 to 45 degree angle with the bevel up.

  • The needle is slowly advanced into the artery until blood appears in the needle hub. (Arterial pressure should cause blood to pump into the syringe)

  • A plastic syringe and a small needle are used-plunger may have to be very carefully pulled back

  • If blood does not appear, the needle may be slightly redirected but must remain under the skin.
• Needle Removal

  • When enough blood has been collected, remove

  the needle and apply firm pressure to the site

  with a gauze pad.

  • Application of pressure for longer than 5 minutes

  may be necessary for patients receiving

  anticoagulant therapy

  • With the hand holding the syringe, immediately

  expel any air that has entered the sample.

  • Activate the needle protection shield, remove

  the needle, and apply the Luer cap or insert the

  needle into a Point lok device.

  • Immediately rotate the syringe to mix the

  anticoagulant with the entire sample.
• Completion of the Procedure

  • The sample is labeled and, if using a glass syringe, placed in an ice-water bath.

  • After pressure has been removed for 2 minutes, the patient’s arm is rechecked to be sure that a hematoma is not forming, in which case additional pressure is required.

  • The radial artery is checked for a pulse below the puncture site, and the nurse is notified if a pulse cannot be located-indicate a possible arteriospasm.

  • A pressure bandage is applied if no complications are discovered