Johanesen et al used Doppler ultrasonography to identify occult arterial trauma in an injured extremity. The authors are from Harborview Medical Center in Seattle.
Patient selection: injured extremity
Examination: Doppler ultrasonography
Parameters:
(1) systolic arterial pressure in the injured extremity in mm Hg
(2) systolic arterial pressure in an uninvolved arm in mm Hg
Doppler arterial pressure index (API) =
= (systolic arterial pressure in injured extremity) / (systolic arterial pressure in uninvolved arm)
Interpretation:
• An API < 0.90 is associated with a major arterial injury with a sensitivity of 95% and specificity of 97%.
• An API >= 0.90 has a negative predictive value of 0.99 for major arterial lesions. However, minor arterial lesions may be present (arteriovenous fistula, pseudoaneurysm).
Angiography is indicated when the API < 0.90.
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