Allen test for lower extremity

Q: The Allen's test should be performed before inserting arterial line catheter in

A) Radial artery 
B) Dorsalis pedis artery 
C) Brachial artery 
D) Femoral artery
E) A and B


Answer: E

It is well known that Allen or modified Allen test should be performed prior to insertion of arterial line in radial artery to assess the collateral circulation via ulnar artery. Similarly, Allen test should be performed if arterial line needs to be inserted in dorsalis pedis artery to assess collateral circulation via posterior tibial artery. It is performed by elevating the lower extremity until the plantar skin blanches followed by compression of dorsalis pedis artery and lowering of extremity to dependency. The foot rapidly resumes color if the posterior tibial artery flow is adequate. Allen test for lower extremity has also been described with  Doppler signals.

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Reference: 

Haddock N.T., Garfein E.S., Saadeh P.B., Levine J.P. (2009) The lower-extremity allen test. Journal of Reconstructive Microsurgery, 25 (7) , pp. 399-403.