Arterial Puncture for Blood Gas Analysis: Nurses procedure by nursesnote

 Arterial Puncture for Blood Gas Analysis 

Equipment 

• Blood gas kit
• 2 or 3 ml syringe 
• 23 or 25 G needle 
• 0.5 ml sodium heparin (1:1000)
• Lidocaine (if needed)
• Sterile germicide
• Gloves
• Goggles 
• Cup or plastic bag with crushed  ice
• Rolled towel or washcloth 

Procedure 

Preparatory phase 

• Record the patient's inspired oxygen concentration. 
• Changes in inspired oxygen concentration after the changes in PaO2. Degree of hypoxaemia cannot be assessed without knowing the inspired oxygen concentration. 
• Take the patients temperature. 
• May be considered when results are evaluated. Hyperthermia and hypothermia influence oxygen release from hemoglobin. 
• Heparinize the 2-ml syringe. Withdraw heparin into the syringe to wet the plunger and fill dead space in the needle. Hold the syringe in an upright position and expel excess heparin and air bubbles.
• This action coats the interior of the syringe with heparin to prevent blood from clotting. Air in the syringe may affect measurement of PaCO2; heparin in the syringe may affect measurement of the pH. Heparin left in the syringe can decrease the pH.

Performance Phase 

• Verify correct patient; perform hand hygiene. 
• Put on gloves and goggles. 
• Palpate the radial, brachial, or femoral artery. 
• The radial artery of the non-dominant side is the preferred site of puncture but is contraindicated if a fistula or shunt for dialysis exists. Arterial puncture is performed on areas where a good pulse is palpable. 
• If puncturing the radial artery, perform the Allen test.
• The Allen test is a simple method for assessing collateral circulation in the hand. Ensures circulation if radial artery thrombosis occurs.
• Obliterate the radial and ulnar pulses simultaneously by pressing on both blood vessels at the wrist.
• Impedes arterial blood flow into the hand.
• Ask the patient to clench and unclench his fist until blanching of the skin occurs. 
• Forces blood from the hand.
• Release pressure on ulnar artery (while still compressing radial artery). Watch for return of skin color within 15 seconds. 
• Documents that ulnar artery alone is capable of supplying blood to the hand because radial artery is still occluded. 
• Note: if the ulnar does not have sufficient blood flow to supply the entire hand, the radial artery should not be used.

In the unconscious patient:

• Obliterate the radial and ulnar pulses simultaneously at the wrist.
• Elevate the patient's hand above the heart and squeeze or compress, his hand until blanching occurs. 
• Lower the patient's hand while still compressing the radial artery ( release pressure on ulnar artery ) and watch for return of skin color.
• For the radial site, turn palm up and mildly hyperextend the wrist, placing a small towel roll under the patient's wrist. 
• To make the artery more accessible. 
• Feel along the course of the radial artery and palpate for maximum pulsation with the middle and index fingers. Prepare the skin with germicide; allow to dry completely. The skin and subcutaneous tissues may be infiltrated with a local anesthetic agent(lidocaine).
• The wrist should be stabilized to allow for better control of the needle. 
• The needle is at a 45 to 60-degree angle to the skin surface and is advanced into the artery. Once the artery is punctured, arterial pressure will push up the hub of the syringe and a pulsating flow of blood will fill the syringe. 
• The arterial pressure will cause the syringe to be filled within a few seconds; about 2 ml will accumulate and the flow into the syringe will stop.
• After the blood is obtained, withdraw the needle and apply firm pressure over the puncture with dry sponge. 
• Significant bleeding can occur because of pressure in the artery. 
• Remove air bubbles from syringe and needle. Use safety syringe system for closure. 
• Proper closure of the needle prevents room air from mixing with the blood specimen. 
• Place the capped syringe in the container of ice. Label as per facility policy. 
• Icing the syringe will prevent a clinically significant loss of oxygen. 
• Maintain firm pressure on the puncture site for 5 minutes, if the patient is an anticoagulant medication, apply direct pressure over puncture site for 10 to 15 minutes and then apply a firm pressure dressing. 
• Firm pressure on the puncture site prevent further bleeding and hematoma formation. 
• For patient requiring serial monitoring of arterial blood, an arterial catheter is inserted into the radial or femoral artery. 
• All connection must be tight to avoid disconnection and rapid blood lose, The arterial also allows for direct blood pressure monitoring in the critically ill patient. 

Follow - up - phase

• Send the labelled, iced specimen to the laboratory immediately. 
• Blood gas analysis should be done as soon as possible because PaO2 and pH can change rapidly. 
• Palpate the pulse ( distal to the puncture site), inspect the puncture site, and assess for cold hand, numbness, tingling or discoloration. 
• Hematoma and arterial thrombosis are complications following this procedure. 
• Change ventilator settings, inspired oxygen concentration or type and setting of respiratory therapy equipment if indicated by the result. 
• The PaO2 results will determine whether to maintain, increase, or decrease the FiO2. The PaO2 and pH results will detect if any changes are needed in tidal volume or rate of patient's ventilator. 

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