Skill List > Blood Pressure Recording: Electronic 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: June 2017
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/web sites and completing the self-test quiz you should be ready to be assessed in practice in the skill of blood pressure recording using an electronic 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 mmHg 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).

For the nurse, BP measurement is part of the routine observations done 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.

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).

Preparation and safety

  • The hands should be clean. An apron is usually all that is required but additional PPE (personal protective equipment or 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 if at all possible. 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.
  • If the patient has an irregular pulse (such as those with atrial fibrilliation) electronic devices may not measure blood pressure accurately. If this is known or suspected, the nurse should palpate the radial pulse before measuring blood pressure. If pulse irregularity is present, the blood pressure should be measured with a manual device and stethoscope (NICE 2016).
  • The machine and cuff 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 additional PPE if 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 raised blood pressure.
  3. Switch on the machine and check whether it will operate on battery. If necessary, plug it into the mains.
  4. 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.
  5. 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.
  6. The arm should be positioned so that the cuff is level with the patient’s heart and the patient’s arm is relaxed.
    Rationale – If the arm is lower than the heart, it could lead to overestimation of the systolic BP by up to 10 mmHg; and if higher than the heart, it may lead to underestimation. 
  7. Warn the patient that the cuff will inflate and press the start button. After several seconds the systolic and diastolic blood pressure will be displayed.
  8. If a standing blood pressure is required, ask or assist the patient to get out of 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).
  9. Unless very frequent blood pressure recordings are required (e.g., every 15 min), switch off the machine and remove the cuff.
    Rationale – 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.
  10. Document the blood pressure accurately according to local policy.
  11. 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 mmHg (British Hypertension Society 2012).
    Rationale – It is vital to report any concerns to the nurse in charge or a doctor. Most hospital charts will incorporate use of an Early Warning Score that gives parameters and guidance about appropriate actions if the observations are above or below the normal (Royal College of Physicians (RCP) 2015).
  12. Replace clothing and ensure the patient is comfortable and drinks and belongings etc. are within reach.
  13. The machine and cuff should be cleaned according to local policy.
  14. Plug the machine into the mains so that the battery is fully charged at all times. Leave equipment tidy and ready for use.

Ongoing care, monitoring and support

  • 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 old or over.
  • Most NHS Trusts offer clinics and other support to help people who want to adopt a healthier lifestyle. Nurses can help people with hypertension to reduce their risk by advising the following (NHS Choices 2012): 
    • weight loss, if overweight
    • regular exercise
    • a healthy diet
    • reducing alcohol intake
    • stopping smoking
    • reducing their intake of salt and caffeine.

Documentation and reporting

  • Accurate documentation and prompt reporting of any changes in BP are 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 (RCP 2015).
  • At present NHS Trusts and other institutions use different early warning scores (EWS); however, the Royal College of Nursing has collaborated with the Royal College of Physicians to produce National Early Warning Scores (NEWS) for acute illness in the NHS with an aim to standardise practice nationally (RCP 2015).
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