Blood Pressure Measurement – OSCE Guide

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Blood pressure (BP) measurement often appears in OSCEs and you’ll be expected to confidently carry out the procedure. This blood pressure measurement OSCE guide provides a clear step-by-step approach to measuring blood pressure, with an included video demonstration.


Gather equipment

Gather the relevant equipment for measuring blood pressure:

  • Stethoscope
  • Sphygmomanometer: ensure you have an appropriately sized cuff. A cuff that’s too small may overestimate BP and a cuff that’s too large will underestimate BP.

Introduction

Wash your hands and don PPE if appropriate.

Introduce yourself to the patient including your name and role.

Confirm the patient’s name and date of birth.

Briefly explain what the procedure will involve using patient-friendly language: “Today I would like to measure your blood pressure, this will involve inflating a cuff around your arm whilst listening to your pulse with my stethoscope. The procedure shouldn’t be painful, but it may feel a little uncomfortable when the cuff is fully inflated and you might experience some pins and needles in your hand. If at any point you want me to stop, just let me know.”

Gain consent to proceed with blood pressure measurement.

Position the patient sitting on a chair, with their arm comfortably placed at approximately heart level.

Check if the patient has a preference as to which arm to use. Avoid using an arm that has local pathology such as post-mastectomy lymphoedema.

Ask the patient to adequately expose their upper arm on the relevant side by rolling up their sleeve.

Check if the patient has any pain before proceeding with blood pressure measurement.


Attaching the blood pressure cuff

1. Check that the blood pressure cuff size is appropriate for the patient’s arm and that it is fully deflated.

2. Confirm the location of the brachial artery by palpating medial to the biceps brachii tendon and lateral to the medial epicondyle of the humerus.

3. Wrap the blood pressure cuff around the patient’s upper arm, lining up the cuff marker with the brachial artery.

  • Blood pressure cuff
    Ensure the cuff size is appropriate

Measuring blood pressure

Estimate an approximate systolic blood pressure

To begin with, you need to determine an approximate systolic blood pressure. This is helpful in preventing over-tightening of the cuff during accurate measurement of blood pressure.

1. Ensure the valve on the blood pressure cuff is closed.

2. Palpate the patient’s radial pulse, located at the radial side of the wrist, with the tips of your index and middle fingers aligned longitudinally over the course of the artery.

3. Inflate the blood pressure cuff until you can no longer feel the patient’s radial pulse. Note the reading on the sphygmomanometer at the point at which the radial pulse becomes impalpable. This reading is an approximate estimate of the patient’s systolic blood pressure.

4. Open the valve and deflate the blood pressure cuff.

  • Palpate radial pulse
    Palpate the radial pulse

Measure the blood pressure accurately

Now that you have an approximate systolic pressure, you can perform an accurate assessment of systolic and diastolic blood pressure.

1. Close the valve on the blood pressure cuff.

2. Position the diaphragm of your stethoscope over the brachial artery.

3. Re-inflate the cuff 20-30 mmHg above the systolic blood pressure you previously estimated.

4. Then slowly deflate the cuff at around 2-3 mmHg per second.

5. Using your stethoscope, listen carefully for the onset of a pulsatile noise. The first of these pulsatile noises is known as the first Korotkoff sound. The pressure at which the first Korotkoff sound becomes audible represents the patient’s systolic blood pressure.

6. Continue to deflate the cuff, whilst listening through your stethoscope until the pulsatile sound completely disappears. The final pulsatile noise you hear is known as the fifth Korotkoff sound and represents the patient’s diastolic blood pressure.

7. If the patient’s blood pressure is outside of the normal range you should repeat the assessment on the same arm after a few minutes and also consider assessing blood pressure using the patient’s other arm.

  • Palpate brachial artery
    Palpate the brachial artery
Blood pressure abnormalities

Blood pressure abnormalities may include:

  • Hypertension: a blood pressure of greater than or equal to 140/90 mmHg if under 80 years old or greater than or equal to 150/90 mmHg if you’re over 80 years old.
  • Hypotension: a blood pressure of less than 90/60 mmHg.
  • Narrow pulse pressure: less than 25 mmHg of difference between the systolic and diastolic blood pressure. Causes include aortic stenosis, congestive heart failure and cardiac tamponade.
  • Wide pulse pressure: more than 100 mmHg of difference between systolic and diastolic blood pressure. Causes include aortic regurgitation and aortic dissection.
  • Difference between arms: more than 20 mmHg difference in blood pressure between each arm is abnormal and may suggest aortic dissection.

To complete the procedure

Once an blood pressure has been obtained, remove the blood pressure cuff.

Explain to the patient that the procedure is now complete.

Discuss the blood pressure results with the patient, including any further steps that may need to occur (e.g. follow-up, further investigations, initiation of treatment).

Thank the patient for their time.

Dispose of PPE appropriately and wash your hands.

Document the lowest blood pressure recording in the patient’s notes.


Reviewer

Michelle Spence

Senior Nurse Practitioner 


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