Allen test

Allen Test is a medical procedure used primarily to assess the arterial blood flow to the hands. It was first described by Edgar Van Nuys Allen in 1929, and hence, it is named after him.

Procedure

The Allen test is performed by having the patient clench their fist, which is then elevated. The examiner then occludes both the radial and ulnar arteries, causing the hand to blanch. The patient is then asked to open their hand without moving their wrist. The examiner releases the pressure on one of the arteries, observing the color return to the hand.

Clinical Significance

The Allen test is used to evaluate the integrity of the palmar arch circulation. If color returns as described, Allen's test is considered to be positive and the radial artery may be safely cannulated. If the color fails to return, the test is considered negative and the ulnar artery supply to the hand is not sufficient. This implies that if the radial artery is cannulated, the hand may suffer ischemia.

Variations

There are variations of the Allen test that are used in the assessment of conditions such as Raynaud's disease and thoracic outlet syndrome. These variations may involve different patient positions or movements.

Criticism

The Allen test has been criticized for its lack of sensitivity and specificity. Some studies have suggested that it may not accurately predict the outcome of radial artery cannulation.

See Also

• Radial artery
• Ulnar artery
• Raynaud's disease
• Thoracic outlet syndrome