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Modified Allen Test
Phlebotomy Procedures
Numerical Order | Procedure |
---|---|
1 Rationale | To use the radial artery for blood collection for ABG analysis, the health care worker must first perform the modified Allen test to make certain that the ulnar and radial arteries are providing collateral circulation. |
2 Procedure | Have the patient rest the hand to be used for the test facing upward. |
3 Procedure | Compress both arteries with your index and middle fingers, and ask the patient to tightly clench and unclench his or her fist several times. |
4 Procedure | Ask the patient to open his or her hand, and release the pressure on the ulnar artery. |
5 Procedure | The hand should fill with blood within 5 to 10 secs; if so, the Allen test is (+). A (-) Allen test indicates the inability of the ulnar artery to supply blood to the hand adequately and shows a lack of collateral circulation. |
6 Procedure | Thus, the radial artery should not be used after a (-) Allen test because this artery might be accidentally damaged during the puncture, resulting in a total lack of blood flow to the hand. |
7 Procedure | Select an alternate artery if (-) Allen test occurs. |