Blood Gases, Arterial Synonyms ABG; Arterial Blood Gases; Blood Gas Profile

Applies to Blood Oximetry

Test Includes Measured parameters include pH, pCO₂, and pO₂; calculated parameters include bicarbonate (HCO₃), base excess or deficit (BE), standard bicarbonate, standard base excess, alveolar to arterial oxygen gradient (p_[A-a]O₂), Na^t, K^t, Cl^-, ICa, Hct, glucose, calculated Hgb

Laboratory Core Laboratory

Request Form Stat Requisition

Phone (212) 305-8600

Availability Daily, 24 hours

Turnaround Time 10 minutes

Specimen Blood

Volume 3 mL in a heparinized syringe; place immediately on ice.

Minimum Volume 0.5 mL

Container Syringe (heparinized)

Collection Preheparinized glass or plastic syringes are available in blood gas kits. Syringes preheparinized with liquid heparin should be held vertically, needle up, and the liquid heparin should be pushed into the dead space of the syringe and needle, expelling all air out of the dead space.

If preheparinized syringes are not used, the following procedure should be used. Fit a needle onto the syringe and draw the anticoagulant into it. Draw 0.5-1 mL. Remove the original needle and replace with a sterile needle. Pull and push syringe plunger several times to coat syringe surface. Holding the syringe with the needle up, expel all liquid heparin into needle cap, taking care not to leave any air bubbles in the dead space of the needle.

Perform the Allen test for collateral circulation to determine the best site for puncture. Sites listed in order of preference are the radial, brachial, and femoral arteries. Palpate and visualize the artery. Apply antiseptic to the sampling site. Palpate the site once again, trying to stabilize the artery. Slight hyperextension of the wrist or elbow can be achieved by placing a rolled up towel under the joint; this can aid palpation and stabilization of the artery. Hold the syringe so the bevel of the needle faces upward, keeping the needle at a 25° to 30° angle to the artery. Insert the needle through the skin into the artery taking care not to puncture the posterior wall of the artery. Arterial pressure should cause the blood to flow into the syringe if the plunger fits properly and the barrel has been lubricated with anticoagulant. Withdraw the needle when an adequate sample has been obtained; immediately place dry gauze or cotton over the puncture site and maintain pressure over puncture site for a minimum of 5 minutes (longer if the patient has taken aspirin or anticoagulants). Expel any air bubbles from the sample. Remove needle/cap assembly and replace with a syringe cap. Mix sample gently. The laboratory will not accept specimens with needles.

Storage Instructions Place specimen on ice and send to the Core Laboratory immediately.

Aftercare The puncture site should be compressed for a minimum of 5 minutes, longer if the patient is taking anticoagulant therapy, aspirin or has a prolonged prothrombin time. After 5 minutes, the puncture site should be inspected for several seconds to ensure that clotting has taken place. During this inspection, palpate the pulse proximal and distal to the puncture site to assess the presence of arterial spasm. A sterile bandage should be placed over the puncture site to keep the puncture site clean while healing. Warning: A bandage is not a substitute for compression of the puncture site.

Causes for Rejection Large air bubbles will cause all values to be erroneous, needle left on syringe

Reference Range

pH: 7.35-7.45

pCO₂: male: 35-45 mm Hg, female: 32-43 mm Hg

pO₂: 72-104 mm Hg

BE(C): male: -3.3 to +1.2 mEq/L, female: -2.4 to +2.3

HCO₃: 22-26 mEq/L

Critical Values pH:

7.20 or

7.55; pO₂: <56 mm Hg; pCO₂: >50 mm Hg; HCO₃: <16 mM/L or >39 mM/L

Use Assess oxygenation of arterial blood and the blood's acid-base balance

Methodology Specific gas electrodes