Ankle-Brachial Index

Aka: Ankle-Brachial Index, Ankle-Brachial Ratio, Toe-Brachial Ratio, Toe-Brachial Index

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II. Indications

  1. Claudication
  2. Peripheral Arterial Disease Diagnosis and Monitoring
  3. Screening for Peripheral Arterial Disease
    1. See Peripheral Arterial Disease for screening indications
  4. Vascular Injury Evaluation
    1. Leg Trauma
    2. Posterior Knee Dislocation

III. Contraindications

  1. Known or suspected Deep Vein Thrombosis
  2. Severe Leg Pain (e.g. leg wound, tissue ischemia, Fracture)
  3. Arterial Injury Hard Signs
    1. Active Hemorrhage
    2. Distal pulses absent
    3. Pulsatile or absent Hematoma
    4. Acute Limb Ischemia signs

IV. Efficacy

  1. Test Sensitivity: 90-97%
  2. Test Specificity: 98%

V. Technique

  1. Precautions
    1. ABI may be difficult to obtain in obese, hypothermic or Peripheral Arterial Disease patients
    2. Consider increasing cuff size
    3. Consider repeating exam when well hydrated, warm and after injury stabilization
  2. Measure highest systolic reading in both arms
    1. Record first doppler sound as cuff is deflated
    2. Record at the radial pulse
    3. Use highest of the two arm pressures
      1. Repeat the first arm Blood Pressure if there is a discrepancy between arms >10 mmHg
  3. Measure systolic readings in both legs
    1. Cuff applied to calf, just above the malleoli
      1. Avoid applying over a distal bypass site (risk of bypass thrombosis)
    2. Inflate cuff to 20 mmHg after doppler signal disappears
    3. Record first doppler sound as cuff is deflated
    4. Use Doppler Ultrasound device (8 MHz)
      1. Record dorsalis pedis pressure (absent in 2-3% of normal patients)
      2. Record posterior tibial pressure
    5. Use highest ankle pressure (DP or PT) for each leg
  4. Calculate ratio of each ankle to brachial pressure
    1. Divide each ankle pressure by highest brachial pressure

VI. Interpretation

  1. Absolute ankle pressure <50 mmHg is abnormal
  2. Ankle-Brachial Ratio >=1.4: Non-compressable vessels (see False Negatives below)
  3. Ankle-Brachial Ratio >0.90: Normal
  4. Ankle-Brachial Ratio <0.90: Peripheral Vascular Disease
  5. Ankle-Brachial Ratio <0.6: Intermittent Claudication
  6. Ankle-Brachial Ratio <0.5: Multi-level disease
  7. Ankle-Brachial Ratio <0.3: Limb Threatening Ischemia (requires emergent intervention)
  8. Ankle-Brachial Ratio <0.26: Resting ischemic pain
  9. Ankle-Brachial Ratio <0.2: Gangrenous extremity

VII. Interpretation: False Negative Test - Non-compressable vessels (ABI >=1.4)

  1. Results in falsely elevated ankle pressure
  2. Conditions where vessels are non-compressable or small vessel disease
    1. Diabetes Mellitus
    2. End-stage renal disease (ESRD)
    3. Diffuse arterial calcifications (as in severe or diffuse PAD)
  3. Alternative studies
    1. Toe-Brachial Ratio
      1. Typically 0.7 to 0.8
      2. Abnormal <0.7 (severe if <0.4)
    2. Exercise ABI Testing
      1. Obtain ABI immediately after walking 5 minutes on treadmill at 12% grade and 2.0 miles/h OR
      2. Symptoms require patient to stop

VIII. Management: Abnormal Ankle-Brachial Index (ABI < 0.9 or ABI>1.4)

  1. Segmental Arterial Pressure
  2. Other options
    1. Arterial Duplex Ultrasound
    2. Standard angiography
    3. CT angiography (also consider in Trauma, e.g. posterior Knee Dislocation)
    4. Magnetic resonance angiography

IX. References

  1. Hirsch (2002) Lecture, Fairview Lakes RMC
  2. Warrington (2020) Crit Dec Emerg Med 34(11): 11
  3. Aboyans (2012) Circulation 126: 2890-909 [PubMed]
  4. Carman (2000) Am Fam Physician 61(4):1027-32 [PubMed]

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Related Studies

Ontology: Ankle brachial pressure index (observable entity) (C1328319)

Definition (MSH) Comparison of the BLOOD PRESSURE between the BRACHIAL ARTERY and the POSTERIOR TIBIAL ARTERY. It is a predictor of PERIPHERAL ARTERIAL DISEASE.
Definition (NCI) The ratio of ankle systolic pressure to brachial systolic pressure, used to assess arterial insufficiency in the lower extremities.
Concepts Clinical Attribute (T201)
MSH D055109
SnomedCT 446841001
Italian Indice caviglia-braccio, Indice caviglia-brachiale
Dutch enkel brachialis test, enkel brachialis index
French Test brachial de la cheville, Indice de pression systolique cheville-bras, IPSch, ISD (Indice Systolique de pression Distale), Indice de pression systolique, Index de pression systolique, IPS (Index de Pression Systolique), Indice de pression systolique à la cheville, Index de pression systolique cheville-bras, Index de pression systolique à la cheville, Indice de pression systolique cheville/bras
German Brachialtest am Fussgelenk, Knöchel-Arm-Index, Knoechel-Arm-Index
Portuguese Exame braquial do tornozelo, Índice Tornozelo-Braço, Índice braquial do tornozelo
Spanish Indice tobillo-brazo, Índice Tobillo Braquial, índice de presión braquial/tobillo (entidad observable), índice de presión braquial/tobillo, Indice braquial tobillo
Japanese 足関節／上腕血圧比測定, 足関節／上腕血圧指数, ｿｸｶﾝｾﾂｼﾞｮｳﾜﾝｹﾂｱﾂﾋｿｸﾃｲ, ｿｸｶﾝｾﾂｼﾞｮｳﾜﾝｹﾂｱﾂｼｽｳ, ｱｼｶﾝｾﾂｼﾞｮｳﾜﾝｹﾂｱﾂｼｽｳ, ｱｼｶﾝｾﾂｼﾞｮｳﾜﾝｹﾂｱﾂﾋｿｸﾃｲ, 足関節血圧比, 足関節血圧指数, 足関節上肢血圧比, 足関節-上腕血圧比, 上腕足首血圧比, 足関節/上腕血圧比, 足関節血圧/上腕動脈圧, 足関節上腕血圧比, 足関節圧/上肢血圧
English ankle brachial index (physical finding), ankle brachial index, Brachial Index, Ankle, Index, Ankle Brachial, Brachial Indices, Ankle, Ankle Brachial Indices, Indices, Ankle Brachial, Ankle-Brachial Indices, Indices, Ankle-Brachial, Ankle Brachial Index, Ankle-Brachial Index, Index, Ankle-Brachial, Ankle-Arm Index, Ankle-Arm Pressure Index, Ankle-Brachial Pressure Index, ABI, Ankle brachial pressure index, Ankle brachial test, Ankle brachial pressure index (observable entity), Ankle brachial index
Czech Tlakový test kotník/paže, Tlakový index kotník/paže, kotníko-brachiální index, tlakový index kotník-paže, kotníkový tlak
Russian LODYZHECHNO-PLECHEVOI INDEKS, ЛОДЫЖЕЧНО-ПЛЕЧЕВОЙ ИНДЕКС
Swedish Ankel-brakial index
Polish Wskaźnik kostkowo-ramienny, Wskaźnik stopa-ramię, Wskaźnik kostka-ramię, Wskaźnik ABI, Wskaźnik stopowo-ramienny
Hungarian Boka brachialis vizsgálat, Könyök / boka index
Norwegian Ankel-armindeks, Ankel-brakialindeks
Derived from the NIH UMLS (Unified Medical Language System)

Ontology: Toe Brachial Index (C2116889)

Definition (MSH) An alternative to the ankle-brachial index.
Concepts Diagnostic Procedure (T060)
MSH D055109
English toe brachial index (physical finding), toe brachial index, Index, Toe Brachial, Toe Brachial Indices, Toe-Brachial Index, Toe Brachial Index, Brachial Index, Toe, Index, Toe-Brachial, Brachial Indices, Toe, Indices, Toe Brachial, Indices, Toe-Brachial, Toe-Brachial Indices
French Indice de pression systolique au premier orteil, Index de pression systolique au gros orteil, Indice de pression systolique au gros orteil, Index de pression systolique orteil-bras, Indice de pression systolique orteil-bras, Index de pression systolique au premier orteil
German Zehen-Arm-Index
Czech tlakový index palec-paže, palcový tlak
Norwegian Stortå-brakialindeks, Tå-brakialindeks
Derived from the NIH UMLS (Unified Medical Language System)

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