Pre‐procedure

ActionRationale

1. 1.Show
   Introduce yourself to the patient, explain and discuss the procedure with them, and gain their consent to proceed.
   To ensure that the patient feels at ease, understands the procedure and gives their valid consent (NMC [144], C).
2. 2.Show
   Wash and dry hands and/or use an alcohol‐based handrub.
   To prevent cross‐infection (NHS England and NHSI [124], C).
3. 3.Show
   Assess whether the patient has any of the following:

   • lymphoedema or risk of lymphoedema
   • arteriovenous fistula
   • trauma or surgery to the arm or axilla
   • previous brachial artery surgery
   • intravenous (IV) infusion in progress.

   If there is a contraindication, use the other arm, or, if the condition is bilateral, a lower extremity.
   To ensure there are no contraindications to using a particular arm (Bickley [18], E).

   Taking a blood pressure measurement is not recommended on a limb with an IV infusion in progress because the pressure could damage the vein, placing the patient at risk of extravasation or infiltration (Jackson [86], E). If there is no other choice, blood pressure can be taken on a limb with an IV catheter in situ although the infusion must be temporarily stopped if clinically safe to do so (Tait et al. [194], C).
4. 4.Show
   Provide a relaxed and comfortable environment. The patient should be seated in a chair with back support or supine in bed for at least 5 minutes prior to measuring their blood pressure.
   To enable comparisons to be drawn with prior blood pressure results (NICE [132], C).

   Variations in temperature and emotions can alter blood pressure readings (RCP [172], E).

   Resting for 5 minutes will ensure an optimum reading (RCP [172], E).
5. 5.Show
   Ensure the cuff is the correct size for the arm.
   To prevent falsely high readings, which may occur if small cuffs are used, or falsely low readings, which may occur if large cuffs are used (NICE [132], E; RCP [172], C).
6. 6.Show
   Check the patient's arm is free from clothing, supported (e.g. with a pillow, whether the patient is sitting or standing) and placed at heart level (midsternal level). The patient's bladder should have been emptied recently. Their legs should be uncrossed with their feet flat on the floor (if they are positioned in a chair) and ankles uncrossed (if they are in a bed). See Figure 14.25.
   Taking measurements over clothing or with tight clothing pushed up on the arm can cause a tourniquet effect and also produce significant artefacts (Sprigings and Chambers [189], E).

   If the arm is lower than the heart, it can lead to falsely high readings, and vice versa (NICE [132], E).

   Obtaining a measurement before bladder emptying can increase blood pressure, as can having the legs crossed (Blows [21], E).

Procedure

1. 7.Show
   Wrap the cuff of the sphygmomanometer around the bare arm with the artery marking centred over the brachial artery and superior to the elbow. The lower edge of the cuff should be 2–3 cm above the brachial artery pulsation.
   To obtain an accurate reading and so that the artery can easily be palpated (NICE [132], C).
2. 8.Show
   Ask the patient to stop talking and eating during the procedure.
   Activity can cause a falsely high blood pressure (RCP [172], C).
3. 9.Show
   Palpate the brachial artery while pumping air into the cuff using the bulb. Once the pulse can no longer be felt, rapidly inflate the cuff a further 20–30 mmHg.
   Palpation of the artery prior to obtaining a blood pressure is recommended as it locates the correct position for stethoscope placement (NICE [132], E).

   Although the radial artery is also available for palpating, the brachial artery is selected due to its proximity to the most common cuff position (superior to the elbow). C

   Inflating the cuff to only 20–30 mmHg above the predicted systolic level prevents undue discomfort (Bickley [18], E).
4. 10.Show
   Slowly deflate the cuff and note the point at which the pulse becomes detectable again. This approximates the systolic blood pressure.
   This provides an indication of systolic pressure and can ensure accurate results in patients who have an auscultatory gap (see Box 14.3) (Tortora and Derrickson [199], E).
5. 11.Show
   Deflate the cuff completely and wait 15–30 seconds.
   To allow venous congestion to resolve (Bickley [18], E).
6. 12.Show
   The diaphragm of the stethoscope should be firmly, but without too much pressure, placed on bare skin over the brachial artery where the pulse was palpable.
   The bell of the stethoscope may hear the tone of the Korotkoff sounds better; however, the diaphragm has a larger surface area and is easier to hold in place (Tait et al. [194], E).

   If the stethoscope is in contact with material, it may distort the Korotkoff sounds. In addition, applying pressure may partially occlude the artery (Babbs [9], Bickley [18], E).
7. 13.Show
   Inflate the cuff again to 20–30 mmHg above the predicted systolic blood pressure.
   To ensure an accurate measurement (Bickley [18], C).
8. 14.Show
   Release the air in the cuff slowly (at an approximate rate of 2–3 mmHg per pulsation) until the first tapping sounds are heard (first Korotkoff sound). This is the systolic blood pressure.
   The cuff should not be deflated too quickly as this may result in inaccurate readings being taken (Pan et al. [151], E).
9. 15.Show
   Continue to deflate the cuff slowly, listening to the Korotkoff sounds; the point at which the sound completely disappears is the best representation of the diastolic blood pressure.
   To ensure an accurate diastolic blood pressure measurement (Bickley [18], E).
10. 16.Show
    Once sounds can no longer be heard, rapidly deflate the cuff.
    To prevent venous congestion to the arm (Chen et al. [40], E).
11. 17.Show
    If it is necessary to recheck the blood pressure, wait 1–2 minutes before proceeding (RCP [172]).
    Venous congestion may make the Korotkoff sounds less audible (Bickley [18], E).

Post‐procedure

1. 18.Show
   Inform the patient that the procedure is now finished.
   To reassure the patient (NMC [144], C).
2. 19.Show
   Wash hands using bactericidal soap and water and/or an alcohol‐based handrub. Clean the bell and diaphragm of the stethoscope and cuff with cleaning wipes.
   To minimize the risk of infection (Loveday et al. [106], R; NHS England and NHSI [124], C).
3. 20.Show
   Document as soon as the measurement has been taken and compare it with previous results. Take action as appropriate and document the action.
   Any interruption in the process may result in the measurement being incorrectly remembered (RCP [172], E).

   Records should identify any risks or problems that have arisen and show the action taken to deal with them (NMC [144], C).