Ultrasound-guided radial artery catheterization and the modified Allen's test.

In this case report, ultrasound-guided radial artery catheterization and a modified Allen's test were performed by Emergency Department (ED) physicians to facilitate the management of an intubated, critically injured patient. Ultrasound was demonstrated to be a valuable tool in determining collateral circulation and guiding radial artery cannulation in a patient unable to cooperate with the traditional Allen's test. Ultrasound guidance may reduce the risk of radial artery catheterization in severely injured patients.