Content

• Steps
• Part 1 of 3: Measuring Shoulder Pressure
• Part 2 of 3: Measuring ankle pressure
• Part 3 of 3: Calculating the Ankle Brachial Index (ABI)
• Tips
• Warnings

The ankle-brachial index (ABI) is the ratio of blood pressure in the lower leg or ankle to blood pressure in the arm. Knowing ABI is important because it can be used as an indicator of peripheral arterial disease (PAD). Peripheral arteries in the body can be affected in the same way as coronary arteries (arteries of the heart). They may be clogged with cholesterol or may become stiff due to calcification. A significant difference between blood pressure in the lower legs and arms may indicate peripheral arterial disease. This condition can lead to more serious medical problems such as stroke and heart failure.

Steps

Part 1 of 3: Measuring Shoulder Pressure

1. 1 Ask the patient to lie in a face-up position. The face up position is known as the supine position. Make sure your patient lies on a flat surface with their arms and legs at heart level. Allow the patient to rest for at least 10 minutes before taking their blood pressure. Resting will help to normalize his blood pressure, especially if he is anxious, and will also help to align his heart and shoulder pulse.
   • Both of your patient's arms should be accessible. Sleeves should be loose and rolled up to the side.
2. 2 Find the brachial artery. Use your index and middle fingers to find your heart rate.Do not use your thumb because it has its own pulse and this can make it difficult to find the patient's pulse. Shoulder pulse is usually felt just above the cubital fossa - in the middle of the elbow
3. 3 Place the cuff around the patient's left arm. Make sure the cuff is about 5 cm above the shoulder pulse. To avoid inaccurate readings, make sure the cuff is loose enough so that it can rotate slightly around the arm, but not so loose that it can slide down the arm.
   • If possible, use a blood pressure cuff that is about two-thirds the width of the patient's arm.
4. 4 Inflate the cuff to measure the systolic blood pressure in the arm. To take a blood pressure reading, place the membrane (round part) of the stethoscope over your shoulder pulse. Close the hand pump valve and use it to inflate the cuff to approximately 20 mmHg. above normal blood pressure, or until the patient's pulsating pulse is no longer heard.
   • Systolic pressure characterizes the maximum arterial pressure created as a result of the contraction of the left ventricle of the heart.
   • Diastolic pressure refers to the minimum pressure generated by filling the ventricles with blood during the onset of the cardiac cycle.
5. 5 Release air from the cuff. After opening the valve, slowly release the pressure at a rate of 2 to 3 mmHg, while carefully monitoring the pressure gauge (pressure gauge). Notice when the pulsating sound returns and then when it disappears. Systolic blood pressure is the moment when the pulsating sound returns, and diastolic pressure is when the pulsating sound disappears. Systolic blood pressure is the value you will use later to calculate your ABI.

Part 2 of 3: Measuring ankle pressure

1. 1 Ask your patient to remain in a prone position, face up. The goal is to keep your arms and legs at the same level as your heart for the most accurate blood pressure reading. Remove the blood pressure cuff from your patient's arm.
2. 2 Wrap cuff around the patient's left ankle. Position the cuff five centimeters above the ankle (bony ridge) of your ankle. Make sure the cuff is not too tight. Check the tightness by inserting two fingers. If you cannot insert two fingers, then it is too tight.
   • Make sure you have the correct cuff size for your patient. The width of the cuff should be slightly wider than the diameter of the lower leg.
3. 3 Find the dorsal artery of the foot. The dorsal artery of the foot (a dorsalis pedis) is located on the upper surface of the foot in close proximity to the place where the foot crosses the ankle. Apply ultrasound gel to this top of the foot. Position the Doppler ultrasound probe on the strongest point of the dorsal artery of the foot. Move the sensor around until you find the place with the loudest heart rate. You should hear a throbbing or whistling sound.
4. 4 Record the blood pressure in the dorsal artery of the foot. Inflate the blood pressure cuff to 20 mmHg. above the patient's normal systolic pressure or until the whistling sound from the Doppler transducer disappears. Deflate the cuff and notice when the whistling sound returns. This is the systolic blood pressure at the ankle.
5. 5 Find the posterior tibial artery (a.posterior tibial). For a more accurate ABI, you should measure the blood pressure in both the dorsal artery of the foot and the posterior tibial artery. The posterior tibial artery is located on the back of the lower leg, about one quarter of the way up.Apply ultrasound gel to this area and use a Doppler probe to locate where the posterior tibial pulse is heard most strongly.
6. 6 Record the blood pressure in the posterior tibial artery. Repeat the same process as for the dorsal artery of the foot. When you are finished registering pressure, switch the cuff to your right leg. Record the blood pressure in the dorsal artery of the foot and in the posterior tibial artery in the right leg.

Part 3 of 3: Calculating the Ankle Brachial Index (ABI)

1. 1 Record the higher systolic blood pressure at the ankle. Compare the readings on the left and right ankle, as well as the readings in the dorsal artery of the foot artery and in the posterior tibial artery of both ankles. The ABI is calculated using the highest score at each ankle.
2. 2 Divide ankle systolic blood pressure versus arm systolic blood pressure. Calculate the LPI for each leg separately. Use the largest value from your left ankle artery reading and divide by the brachial artery reading. Then repeat this process with your right ankle results.
   • Example: systolic blood pressure at the left ankle 120 and systolic blood pressure at the arm 100.120/110 = 1.02.
3. 3 Record and interpret the result. The normal resting ankle-brachial index is 1.0 to 1.4. The closer the patient's ABI to 1, the better the outcome. This means that the blood pressure in the arm should be as close as possible to the blood pressure in the ankle.
   • An ABI less than 0.4 suggests severe peripheral arterial disease. The patient may develop non-healing ulcers or gangrene.
   • An ABI of 0.41-0.90 indicates mild to moderate peripheral arterial disease and requires further investigations such as CT, MRI, or angiography.
   • An ABI of 0.91-1.30 indicates normal vessels. However, a value between 0.9-0.99 can cause pain during exercise.
   • An ABI> 1.3 indicates uncompressible and highly calcified vessels that artificially increase blood pressure. Years of diabetes or chronic kidney disease can lead to this condition.

Tips

• Symptoms of peripheral artery disease include pain in the legs when walking, non-healing sores on the fingers, feet or legs, discoloration and hair loss on the legs, cold and clammy skin, etc.
• To rule out the early stages of peripheral vascular disease, the ankle-brachial index should be measured by heavy smokers, people with diabetes for more than 50 years, people with a family history of cardiovascular disease, and people with high cholesterol - even if they have no symptoms.
• If the patient has a wound on the shoulder or foot, use sterile gauze to protect the wound before wrapping the cuff.
• Check your doctor's instructions or any special circumstances to consider before doing the procedure. Determining brachial blood pressure in a dialysis patient may be a contraindication for this procedure.
• Check the general condition of the patient. Other pathological conditions can affect the accuracy of the procedure.

Warnings

• Unless you have been trained to use a blood pressure cuff or take a blood pressure reading, you or the person you are helping should see a doctor for an accurate certified ABI reading.