Which of the following test should be done to check ulnar circulation of hand before performing arterial catheterisation?

Appeared in: NORCET 3 - 2022 (Shift-2)

Explanation

The Modified Allen's Test (MAT) is the standard procedure to confirm the patency of the ulnar artery.
It assesses if collateral circulation is sufficient to supply the hand in case the radial artery is compromised during or after cannulation.
A positive (normal) test, indicated by the hand flushing within 5-15 seconds after releasing ulnar pressure, confirms it is safe to proceed.
This test is a critical safety measure to prevent rare but serious complications like hand ischemia, necrosis, or gangrene.

Option A: The original Allen test is a historical predecessor. The Modified Allen's Test (MAT) is the current, more reliable standard for assessing collateral circulation before radial artery cannulation.
Option C: The Schick test is an intradermal test used to determine susceptibility to diphtheria. It has no function in assessing blood circulation.
Option D: The Braden Scale is a risk assessment tool for predicting the likelihood of a patient developing pressure injuries (pressure ulcers). It evaluates factors like mobility and nutrition, not arterial patency.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Assessment of collateral circulation in the hand before arterial procedures as background academic context rather than a clinical decision trigger.
Performing the MAT is a mandatory nursing responsibility before any radial artery puncture (for ABG sampling) or cannulation (for an arterial line).
Failure to confirm adequate collateral circulation can lead to catastrophic hand ischemia if the radial artery thromboses, potentially resulting in loss of function or even amputation.
Documentation of the MAT result (e.g., 'Positive Allen's test, right wrist') is a crucial part of the patient's medical record before the procedure.

How to Approach the Question

First, identify the core of the question: it asks for a specific test related to 'ulnar circulation' before 'arterial catheterisation'.
Recall or look for the standard pre-procedural assessment for radial artery access. This is a common nursing procedure.
Analyze the options. 'Allen test' and 'Modified Allen's test' are directly related to hand circulation. 'Schick Test' (diphtheria) and 'Braden Scale' (pressure ulcers) are clearly unrelated and can be eliminated.
Differentiate between the 'Allen test' and the 'Modified Allen's test'. The modified version is the current standard of care, making it the most precise and correct answer.
Confirm the procedure by visualizing the steps: occlude both arteries, blanch the hand, release one artery, and watch for color return. This matches the description of the MAT.

Concept Tested & Keywords

Concept Tested: Assessment of collateral circulation in the hand before arterial procedures.
Stem keywords: ulnar circulation, hand, arterial catheterisation
Lead-in keywords: test, check

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

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

E6 Medicine Harrison 22e Part 1 p. 1903-1905

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