Skill List > Blood Pressure Recording: Manual Aneroid Sphygmomanometer
Clinical Alert
Elsevier Clinical Skills covers the principles of this procedure. You must follow local policies and procedures regarding technique, equipment used and documentation.
Authors:
Based on Nicol: Essential Nursing Skills 4E
Adapted by: Professor Maggie Nicol
BSc(Hons) MSc(Nursing) PGDipEd RN
Updated by: Tanya Middlehurst MSc BSc(Hons) RN
Last updated: May 2017

Estimating the systolic blood pressure. (From Nicol M, Bavin C, Cronin P, et al. 2012 Essential Nursing Skills, 4th edn. Mosby Elsevier, Edinburgh.)
Listening for the Korotkoff sounds. (From Nicol M, Bavin C, Cronin P, et al. 2012 Essential Nursing Skills, 4th edn. Mosby Elsevier, Edinburgh.)
Example of an early warning score. (From Nicol M, Bavin C, Cronin P, et al. 2012 Essential Nursing Skills, 4th edn. Mosby Elsevier, Edinburgh.)
Learning Objective
After reading the skill overview, watching the video, following up some of the references/websites and completing the Self Test quiz you should be ready to be assessed in practice in the skill of recording blood pressure using a manual aneroid sphygmomanometer.

Introduction

Blood pressure (BP) refers to the pressure exerted by the blood on the blood vessel wall and is a consequence of blood flow and peripheral resistance, created by the peripheral vessels. This can be shown as the following equation: BP = peripheral resistance x cardiac output (Webster & Thompson 2011). Where possible the same arm should be used for repeated BP measurements because there may be a variation of up to 20 mm Hg between the arms (Griffith & Thomason 2013). If a variation between arms is detected, the arm with the higher BP should be used (National Institute for Health and Clinical Excellence (NICE) 2016).

BP measurement is part of the routine observations carried out by the nurse many times each day. However, although routine and often delegated to junior members of the healthcare team, accurate observations are a vital part of patient care. Many treatments and medicines are adjusted according to the patient’s response, which is monitored through their clinical observations.

Electronic BP machines are frequently used in hospitals but it is crucial that nurses know how to perform manual BP recording as electronic machines are not readily available in the community setting. Also, a manual recording is often requested when a patient’s BP is very low or very high.

There is no such thing as a ‘normal’ blood pressure as it varies between individuals and within individuals from moment to moment. Factors such as age, gender, and race influence BP and it varies with exercise, emotional reactions, sleep, digestion, and the time of day (Webster & Thompson 2011). The normal range for resting blood pressure in adults is 90/60140/90 and the optimal BP is a systolic pressure of less than 120 with a diastolic pressure of less than 80 mm Hg (British Hypertension Society 2012).

Preparation and safety

  • Explain the procedure to gain consent and cooperation.
  • The hands should be clean. An apron is usually all that is required, but additional personal protective clothing may be necessary if indicated by the patient’s condition (e.g., MRSA, Clostridium difficile).
  • To ensure an accurate resting BP, patients should relax for at least 15 min prior to the recording and be resting in a bed, couch, or chair in a quiet location with their legs uncrossed. Patients should be asked not to talk during the procedure (British Hypertension Society 2012).
  • If a patient is receiving intravenous therapy, do not use the arm with the intravenous cannula. Also avoid using the same arm as the pulse oximeter (oxygen saturation) probe as this will cause the oximeter to alarm.
  • If a comparison between lying and standing blood pressure is required, the ‘lying BP’ recording should be done first. After recording the lying BP leave the cuff in place, ask the patient to stand, and then repeat the procedure.
  • The sphygmomanometer should be cleaned before and after the procedure according to local policy. Some patients may have their own disposable cuff.

Procedure

  1. Perform hand hygiene and put on a disposable apron. Wear personal protective equipment where necessary.
    Rationale – To prevent-cross infection.
  2. Explain the procedure, to gain consent and cooperation.
    Rationale – To obtain an accurate BP the patient should be rested and relaxed. Anxiety, exercise, or activity will cause a raised blood pressure.
  3. Apply the cuff with no clothing beneath it. If clothing constricts blood flow in the arm, remove the arm from the sleeve.
    Rationale – Restrictive clothing will constrict blood flow and lead to an inaccurate BP.
  4. Apply the cuff so that the centre of the ‘bladder’ (thicker) part is over the brachial artery, just above the front of the elbow known as the antecubital fossa.
    Rationale – The cuff must be the correct size to ensure an accurate recording. The bladder part of the cuff must cover at least 80% of the circumference of the arm. This is usually marked on the cuff. If the cuff is too small or too large (goes round the arm and overlaps) it will lead to an inaccurate measurement.
  5. The arm should be positioned so that the cuff is level with the patient’s heart and the patient’s arm relaxed.
    Rationale – If the arm is lower than the heart it could lead to overestimation of the systolic BP by up to 10 mm Hg, and if higher than the heart it may lead to underestimation. If the arm is held rigid, muscle tension can lead to a false reading (Nicol et al. 2012).
  6. The sphygmomanometer should be placed on a firm surface, with the dial clearly visible and the needle at zero.
    Rationale – If the needle is not at zero there may be air trapped in the cuff. Remove the cuff and squeeze to remove any air. If it is still not at zero send it for recalibration and use another sphygmomanometer.
  7. Estimate the systolic BP by palpating the radial or brachial pulse. Warn the patient and squeeze the bulb slowly to inflate the cuff while still feeling the pulse. Observe the dial and note the level when the pulse can no longer be felt (Figure 1); this is the estimated systolic pressure. Open the valve fully to quickly release the pressure in the cuff.
    Rationale – Estimating the systolic BP avoids having to inflate the cuff unnecessarily high. It is important to inflate the cuff at a steady rate while feeling the radial or brachial pulse and pause between squeezes of the bulb to see if you can still feel the pulse. It is only an estimate and so does not have to be exact.
  8. If using a communal stethoscope, clean the earpieces with an alcohol swab or locally recommended cleaning wipe. Curve the earpieces slightly forwards and place them in your ears.
    Rationale – By curving the earpieces forwards they will be more comfortable and fit snugly in your ears, making it easier to hear the Korotkoff sounds.
  9. Palpate the brachial artery, which is located on the medial aspect of the antecubital fossa, just to the side of the midline, on the side nearest to the patient.
    Rationale – Palpating it before placing your stethoscope means that you know exactly where to place the stethoscope to be able to hear an accurate blood pressure.
  10. Place the diaphragm of the stethoscope directly over the artery and ask the patient to relax their arm (Figure 2). You will not hear anything at this point.
    Rationale – Muscle tension may cause a falsely high reading. The Korotkoff sounds will not be heard until the cuff is being deflated (step 13).
  11. Position yourself so that the dial of the sphygmomanometer is clearly visible (Figure 2).
    Rationale  To ensure you can clearly see the markings on the dial as you deflate the cuff.
  12. Close the valve on the bulb, warn the patient and inflate the cuff to 30 mm Hg above the estimated systolic pressure noted earlier. Gradually open the valve to allow the needle of the dial to drop slowly and steadily; 2 mm/s is the recommended rate.
    Rationale  It is important to deflate at a steady rate to enable you to identify the exact systolic and diastolic pressures to the nearest 2 mm Hg.
  13. While observing the needle of the dial as it falls, listen for thudding sounds known as Korotkoff sounds:
    1. note the exact level where the first ‘thud’ is heard; that is the systolic pressure
    2. then note the exact level where the sounds disappear; that is the diastolic pressure.
  14. Once the sounds have disappeared, open the valve fully to completely deflate the cuff and remove the cuff from the patient’s arm.
     Rationale  Deflate the cuff quickly once the Korotkoff sounds have disappeared as it is quite uncomfortable for the patient.
  15. If a standing blood pressure is required, ask or assist the patient to get out bed and repeat the procedure. Be aware that the patient may feel faint or dizzy.
    Rationale – Postural hypotension (also known as orthostatic hypotension) is defined as a fall of 20 mmHg within 3 min of standing upright (Windsor et al. 2016). It is more common in older adults, especially patients with Parkinson's disease and diabetic neuropathy. It can occur in those taking medications such as diuretics, antidepressants or levodopa, patients who are dehydrated and those who have been on prolonged bed rest (Windsor et al. 2016).
  16. Unless very frequent blood pressure recordings are required (e.g. every 15 min) remove the cuff.
    RationaleThe frequency of observations will be determined by the patient’s condition. When seriously ill or immediately following an operation or investigation it is usual to monitor TPR, BP, and oxygen saturation every 15 min for the first 2 h and then gradually reduce the frequency as the observations return to normal and the patient’s condition stabilises.
  17. Document the blood pressure accurately according to local policy and report any variation from previous recordings. The normal range for resting blood pressure in adults is 90/60140/90 and the optimal BP is a systolic pressure of less than 120 with a diastolic pressure of less than 80 mm Hg (British Hypertension Society 2012).
    Rationale – It is vital to report any concerns to a nurse in charge or doctor. Most hospital charts will incorporate use of an Early Warning Score (EWS) that gives parameters and guidance about appropriate actions if the observations are above or below the normal (Royal College of Physicians 2015).

    Ongoing care, monitoring and support

    • Replace clothing and ensure the patient is comfortable and make sure that drinks, belongings, etc. are within reach.
    • Leave equipment tidy and ready for use. If a communal stethoscope was used, clean the earpieces.
    • The sphygmomanometer and cuff should be cleaned according to local policy.
    • Regular BP measurement is required for most patients while in hospital. The frequency of observations will be determined by the patient’s condition. When seriously ill or immediately following an operation or investigation it is usual to monitor TPR, BP, and oxygen saturation every 15 min for the first 2 h and then gradually reduce the frequency as the observations return to normal and the patient’s condition stabilises.
    • Low BP (hypotension) means that the BP is not sufficient for adequate tissue perfusion and so requires urgent treatment. This may occur due to blood loss following an operation or trauma (hypovolaemic shock) or decreased cardiac output (e.g., following a heart attack) or in septicaemia when toxins cause the blood vessels to dilate and can cause severe hypotension.
    • High BP (hypertension) increases the risk of heart attack and stroke. There is often no clear cause but there is an increased risk in people who (NHS Choices 2012):
      • are overweight
      • have a relative with high blood pressure
      • are of African or Caribbean descent
      • have a lot of salt in their diet
      • do not eat enough fruit and vegetables
      • do little exercise
      • drink a lot of coffee (or other caffeine-based drinks)
      • drink a lot of alcohol
      • are 65 years or over.
    • Most NHS Trusts offer clinics and other support to help people who want to adopt a more healthy lifestyle. Nurses can help people with hypertension to reduce their risk by advising the following:
      • weight loss if overweight
      • regular exercise
      • a healthy diet
      • reducing alcohol intake
      • stopping smoking
      • reducing intake of salt and caffeine (NHS Choices 2012).

    Documentation and reporting

    • Document the blood pressure accurately according to local policy.
    • Report any variation from previous recordings. The normal range for resting blood pressure in adults is 90/60140/90; the optimal BP is a systolic pressure of less than 120 with a diastolic pressure of less than 80 mm Hg (British Hypertension Society 2012).
    • Accurate documentation and prompt reporting of any changes in BP is vital for patient safety. Most hospitals use an Early Warning Score (EWS) that gives parameters and guidance about the appropriate actions (i.e., who to contact, whether to increase the frequency of observations, etc.) if the observations are above or below the normal (Donohue & Endacott 2010). See Figure 3 for an example of an EWS.
    • At present NHS Trusts and other institutions use different EWSs but the Royal College of Physicians has recently called for a nationally agreed Early Warning Score (NEWS) to be developed and argues that this would save 6000 lives a year (Royal College of Physicians 2015).
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