Allen test

Indications: - the Allen test is done prior to obtaining samples of arterial blood from the radial artery for arterial blood gas analysis. - this is to ensure adequate collateral circulation prior to puncturing the radial artery Procedure: - with the patient resting, palms up, ask the patient to make a fist with one hand - compress both the radial artery & ulnar artery between your thumbs & fingers - ask the patient to open his/her hand - the palm should be pale in color - release the pressure over the ulnar artery - the palm should flush in about 3-5 seconds if the ulnar artery is patent - patency of the radial artery may be checked by repeating the procedure, instead releasing pressure over the radial artery

References

Guide to Physical Examination & History Taking, 6th edition, Bates B, JB Lippincott, Philadelphia, 1995, pg 441