Arterial Pressure Index


Arterial Pressure Index, API

  • Indications
  1. Extremity Gunshot Wound evaluation (in which bullet trajectory is in vicinity of a major blood vessel)
  • Definition
  1. Arterial Pressure Index (API)
    1. Compares systolic pressure in injured extremity with uninjured extremity
  2. Contrast with Ankle Brachial Index (ABI)
    1. ABI is indicated in Peripheral Vascular Disease evaluation to compare systolic Blood Pressure between ankle and Forearm
  • Technique
  1. Measure systolic Blood Pressure readings
    1. Injured extremity systolic Blood Pressure
    2. Contralateral uninjured extremity systolic Blood Pressure
  2. Arm is injured extremity: Obtain bilateral standard brachial systolic pressure
  3. Leg is injured extremity: Ankle systolic pressure in both legs
    1. Cuff applied to calf
    2. Record first doppler sound as cuff is deflated
    3. Use Doppler Ultrasound device
      1. Record dorsalis pedis pressure
      2. Record posterior tibial pressure
  • Calculation
  1. Arterial Pressure Index = (SBP injured) / (SBP uninjured)
  • Interpretation
  1. Arterial Pressure Index > 0.9 suggests no arterial injury
  • References
  1. McGonigal (2013) Trauma Professionals Blog: Trauma MedEd Newsletter, November 2013, p. 4