👤 By the CinnaRN Clinical Content Team🕐 Updated 2026-08-23🏷️ Physiological Adaptation🔖 Free to read, print, and share
Also known as: ABG draw · arterial stick · blood gas
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Use this quick-reference guide to spot, treat, and prevent Arterial Blood Gas Sampling on the NCLEX. Keep it handy during review and on exam day!
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📒 The 1-minute cheat sheet
✅ Before
Allen test → confirm collateral flow
Radial artery most common site
✅ Do
Pressure 5 min (10 if anticoag)
On ice → to lab quickly
Note O2/FiO2 on slip
🧪 Values
pH 7.35-7.45, PaCO2 35-45
HCO3 22-26, PaO2 80-100
🚩 Report
Hematoma, ↓ distal pulse, numbness
📚 Arterial Blood Gas Sampling — full study notes
The cheat sheet above is your quick recall card. These notes go deeper — what it is, what to do first, what must be reported, and what to teach.
Arterial blood gas sampling draws blood from an artery, usually the radial artery, to measure oxygenation, ventilation, and acid-base balance. It guides management of respiratory and metabolic disorders. Memory aid: Allen's test first, then prolonged pressure, and put the sample on ice.
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Key points
Understand these first
The Allen test is performed before a radial puncture to confirm adequate ulnar collateral circulation to the hand.
Firm pressure is applied to the puncture site for at least 5 minutes, or longer if the patient is on anticoagulants.
The sample is placed on ice and transported promptly to prevent altered results from continued cell metabolism.
The syringe is heparinized and air bubbles are expelled to avoid falsely altered values.
Recent suctioning, oxygen changes, or position changes should be documented because they affect results.
ABG values interpret pH, PaCO2, PaO2, and HCO3 to identify the acid-base disturbance.
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Nursing priorities
What to do, in order
Perform the Allen test before a radial artery puncture to verify collateral circulation.
Note the patient's current oxygen delivery and temperature on the requisition.
Apply firm continuous pressure to the site for at least 5 minutes, longer if anticoagulated.
Expel air bubbles, place the sample on ice, and transport it to the lab immediately.
Monitor the site for bleeding, hematoma, and adequate distal circulation afterward.
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Red flags — report now
Escalate immediately
Report a cool, pale, or pulseless hand distal to the puncture indicating compromised circulation.
Report continued bleeding or an expanding hematoma at the arterial site.
Report ABG results showing severe hypoxemia or dangerous acid-base imbalance immediately.
Never skip the Allen test before a radial arterial puncture.
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Labs & values
Numbers to know
pH: 7.35-7.45
PaCO2: 35-45 mm Hg
PaO2: 80-100 mm Hg
HCO3: 22-26 mEq/L
SaO2: 95-100%
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Patient teaching
What patients must know
The arterial stick may hurt more than a regular blood draw because the artery is deeper.
We will hold pressure on the site for several minutes to stop bleeding.
Keep the area still afterward and report any swelling or renewed bleeding.
Tell the nurse if your hand becomes cold, numb, or pale after the draw.
❓ Arterial Blood Gas Sampling: NCLEX FAQs
What are the priority nursing interventions for Arterial Blood Gas Sampling?
Perform the Allen test before a radial artery puncture to verify collateral circulation. Note the patient's current oxygen delivery and temperature on the requisition. Apply firm continuous pressure to the site for at least 5 minutes, longer if anticoagulated. Expel air bubbles, place the sample on ice, and transport it to the lab immediately.
What are the warning signs of Arterial Blood Gas Sampling a nurse must report?
Report a cool, pale, or pulseless hand distal to the puncture indicating compromised circulation. Report continued bleeding or an expanding hematoma at the arterial site. Report ABG results showing severe hypoxemia or dangerous acid-base imbalance immediately. Never skip the Allen test before a radial arterial puncture.
What do I need to know about Arterial Blood Gas Sampling for the NCLEX?
The Allen test is performed before a radial puncture to confirm adequate ulnar collateral circulation to the hand. Firm pressure is applied to the puncture site for at least 5 minutes, or longer if the patient is on anticoagulants. The sample is placed on ice and transported promptly to prevent altered results from continued cell metabolism. The syringe is heparinized and air bubbles are expelled to avoid falsely altered values.
What patient teaching is important for Arterial Blood Gas Sampling?
The arterial stick may hurt more than a regular blood draw because the artery is deeper. We will hold pressure on the site for several minutes to stop bleeding. Keep the area still afterward and report any swelling or renewed bleeding. Tell the nurse if your hand becomes cold, numb, or pale after the draw.
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Quick Tip
The Allen test is performed before a radial puncture to confirm adequate ulnar collateral circulation to the hand.