Phlebotomy Test Arterial Blood Gas Collection

Question 1

The Allen test is performed before radial artery puncture to assess:

Accepted Answer

Adequacy of collateral circulation from the ulnar artery

Answer

The Allen test determines whether the ulnar artery can adequately perfuse the hand if the radial artery is damaged during arterial puncture, ensuring collateral circulation is sufficient.

Question 2

What angle of needle insertion is recommended for radial artery puncture for ABG collection?

Accepted Answer

45–60 degrees

Answer

A needle insertion angle of 45–60 degrees is recommended for radial artery puncture, providing the optimal approach to enter the artery at its depth without excessive angulation.

Question 3

After collecting an ABG sample, the syringe should be gently rotated/rolled for at least 5 seconds before capping. This step ensures:

Accepted Answer

The heparin anticoagulant is thoroughly mixed with the blood

Answer

Rolling the syringe mixes the heparin anticoagulant throughout the blood sample, preventing clot formation that would interfere with blood gas analysis.

Question 4

A patient presents with uncontrolled hypertension and is on anticoagulation therapy. When preparing to collect an ABG, the phlebotomist should recognize that anticoagulation therapy requires:

Accepted Answer

Applying pressure for an extended period (5–10 minutes or more) after collection

Answer

Patients on anticoagulants have impaired clotting; pressure must be held for a prolonged time (at least 5 minutes, often 10+ minutes) at the arterial puncture site to achieve hemostasis.

Question 5

If an air bubble enters the ABG syringe during collection, the IMMEDIATE action should be to:

Accepted Answer

Expel the air bubble immediately before capping the syringe

Answer

Air bubbles must be expelled immediately because atmospheric air (high O2, low CO2) will equilibrate with the blood sample, falsely raising PO2 and lowering PCO2.

Phlebotomy Practice Test Practice Test

Phlebotomy Practice Test Practice Test

Phlebotomy Test Arterial Blood Gas Collection