Allen test should be performed before?

Appeared in: AIIMS Delhi NO - 2017

Explanation

The Allen test is a mandatory assessment performed before puncturing the radial artery for an Arterial Blood Gas (ABG) sample.
Its purpose is to confirm the patency of the ulnar artery, ensuring there is adequate collateral blood flow to the hand.
This essential safety precaution prevents potential complications like ischemia or necrosis of the hand if the radial artery becomes occluded during or after the procedure.

Option B: Sputum collection is a non-invasive procedure that involves coughing up phlegm from the respiratory tract. It does not involve any vascular puncture and poses no risk to arterial circulation.
Option C: Stool collection is a non-invasive procedure for diagnostic testing of the gastrointestinal tract. It does not involve the circulatory system in a way that would necessitate an Allen test.
Option D: Urine collection is typically non-invasive (e.g., clean-catch midstream) or involves bladder catheterization. Neither method poses a risk to the arterial circulation of the hand.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Purpose and procedure of the Allen test as background academic context rather than a clinical decision trigger.
Patient safety is the primary reason for performing the Allen test. A positive (abnormal) test result is a contraindication for using that radial artery for puncture.
A positive test, where the hand remains pale for more than 15 seconds after releasing ulnar pressure, indicates inadequate collateral flow and a high risk of ischemic injury.
What if? If the Allen test is positive, the nurse must select an alternative site for the arterial puncture. The next step would be to perform the Allen test on the other wrist. If that is also positive, a different artery, such as the brachial or femoral artery, must be used.

How to Approach the Question

This is a factual recall question that tests your knowledge of a specific clinical procedure.
First, identify the key term in the question: 'Allen test'.
Recall the purpose and clinical indication for this test. The Allen test is specifically designed to assess arterial blood flow in the hand.
Evaluate the given options in this context. Which procedure involves accessing an artery in the hand or wrist?
Recognize that taking an Arterial Blood Gas (ABG) sample is commonly done via the radial artery at the wrist.
The other options (sputum, stool, urine samples) are unrelated to arterial puncture.

Concept Tested & Keywords

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E6 Nursing Fundamentals Potter Perry 12e Part 5 p. 79-81

E6 Anatomy Grays 43e Vol 2 Part 2 p. 73-75

E6 Nursing Brunner Adult Health 3SA Vol 1 Part 2 p. 118-120

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