How do you document a normal Allen test result in a patient?

Documentation of a Normal Allen Test

The Allen test is now considered "only of historical interest" and should not be routinely documented or performed before radial artery access, as it does not predict hand ischemia and an abnormal result should not preclude radial artery use. 1, 2

Current Evidence-Based Practice

Why the Allen Test is No Longer Recommended

• The American Heart Association explicitly states that performing the Allen test to confirm dual arterial circulation is obsolete and has no clinical utility in modern practice 1, 2

• The RADAR trial demonstrated no evidence of hand ischemia in patients undergoing transradial access, even among those with abnormal Allen test results 1, 2

• Recent studies found no differences in thumb capillary lactate, grip strength, or incidence of ischemia between patients with normal versus abnormal Allen test results who underwent transradial access 1

• Hand ischemia from radial artery access is extraordinarily rare due to robust collateral circulation from the ulnar artery through the palmar arch 1, 2

What Should Be Documented Instead

Document the presence of a palpable radial pulse - this is the only assessment that remains clinically relevant before radial artery access 2

• Absent radial pulse is an absolute contraindication to transradial access 2

• Consider ultrasound guidance to assess vessel patency and size, which increases first-attempt success rates and decreases complications 2

If You Must Document an Allen Test (Legacy Situations)

For the modified Allen test technique (though not recommended): 3

• Normal result: "Allen test performed - hand color returned in <5 seconds after ulnar artery release while radial artery remained compressed"

• The test involves occluding both radial and ulnar arteries while patient makes a fist, then releasing only the ulnar artery and observing return of normal color 3

• Traditional interpretation: <5 seconds = clearly positive (adequate collateral flow), 5-9 seconds = moderately positive, ≥10 seconds = negative 4

Critical Clinical Pitfall

Do not deny patients radial artery access based on an abnormal Allen test result - this outdated practice deprives patients of the benefits of transradial approach without evidence-based justification 1, 2

• Radial artery occlusion occurs in <5% of patients with current prevention strategies and is almost always clinically silent when it does occur 1, 2

• The test has poor diagnostic accuracy at all cut-off points, with sensitivity ranging from 54.5% at 6 seconds to 75.8% at 5 seconds 5

What Actually Matters for Radial Access Safety

• Intraprocedural heparin administration (50 U/kg or 5000U) significantly reduces radial artery occlusion 2

• Spasmolytic cocktail (calcium channel blocker with nitroglycerin) reduces radial artery spasm from 15-30% to 6-10% 2

• Ultrasound guidance increases speed and efficacy of access 1, 2