Drawing an arterial blood gas (ABG) requires precise technique to obtain an accurate sample. This involves selecting an appropriate artery, using sterile technique, and carefully inserting the needle.
Selecting the Puncture Site
The most common site for ABG sampling is the radial artery in the wrist. Other potential sites include the brachial artery in the inner arm or the femoral artery in the groin (though these are less frequently used due to increased risk of complications). Always choose the site that minimizes risks to the patient and allows for easy access.
Materials & Preparation
Before starting, gather the necessary supplies:
- Sterile gloves
- Appropriate-sized needle and syringe (usually a 22-25 gauge needle)
- Antiseptic solution (e.g., chlorhexidine or iodine)
- Gauze pads
- Adhesive bandage
- Ice pack (optional)
Step-by-Step Procedure
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Prepare the site: Cleanse the chosen puncture site with an antiseptic solution. Allow to dry completely before proceeding.
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Palpate the pulse: Locate the artery and palpate a strong, consistent pulse. This step is crucial for accurate needle placement.
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Needle insertion: Insert the needle just under the skin at a 45-60º angle, aiming in the direction of the artery. The bevel of the needle should be facing upward. (Ref: Medscape, Cleveland Clinic) While inserting the needle, continue palpating the pulse with your non-dominant hand to confirm correct placement. (Ref: Medscape) Advance the needle slowly.
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Aspirate the blood: Once you feel a flash of blood in the syringe, gently aspirate the sample. This flash confirms you are in the artery.
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Withdraw needle and apply pressure: Remove the needle and immediately apply firm pressure to the puncture site with a gauze pad for at least 5 minutes. This helps prevent hematoma formation.
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Label and submit sample: Label the collected blood sample with the patient's name, date, and time of collection. Deliver the sample to the laboratory immediately, ensuring proper transportation and handling. If there's a delay, keep the sample on ice. (Ref: UTMB)
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Monitor the puncture site: Monitor the patient for bleeding or hematoma formation at the puncture site.
Important Considerations
- Multiple attempts should be avoided: Excessive attempts increase the risk of complications, such as hematoma formation or nerve damage. (Ref: UTMB)
- Allen's test: Before puncturing the radial artery, the Allen's test may be performed to assess collateral circulation. This test ensures there's sufficient blood supply to the hand if the radial artery is compromised during the procedure.
- Post-procedure care: Patient monitoring is needed to prevent complications following ABG collection.
- Only trained medical personnel should perform ABG sampling due to the invasive nature of the procedure. (Ref: Geeky Medics)
