- Light or dial:
- Maintenance/recalibration (Rationale 16):
- They should be serviced yearly by biomedical engineering department to confirm accuracy.
- Date of last calibration should be clearly stated on the manometer (Petrie et al 1986).
- Bladder, tubing, connections, inflation bulb and valves are sound.
- Nylon cuffs should be wiped with disinfectant wipes between patients.
- Fabric cuffs should be washed regularly.
- Disposable or single patient use cuff should be used for children who are considered infectious or immunocompromised.
- good condition
- secure fastening
- correct size
- Length of the bladder (inflatable section):
- Nearly or completely encircle the patients' arm (Arafat 1999) (Diagram 1: Measurement of blood pressure in children/young people. Cuff bladder length should cover 80 per cent to 100 per cent of the circumference of the arm).
- Centre of the bladder over the brachial artery (Rationale 17).
- Width of the bladder:
- This should ideally be the full length from under the arm auxilla to the olecranon (elbow) or the largest cuff that can fit onto the upper arm and still allow auscillation of the brachial artery(Rationale 18)(Appendix 4).
- If these criteria cannot both be met, the largest cuff available for the arm should be used (Beevers et al 2001a; Petrie et al 1986).
Equipment for manual measurement
- Inflation/deflation device:
- Control valves, leaks, vents, tubing - should be clean and not perished.
- The system must be able to inflate rapidly.
- Deflation should be smooth and able to be reduced at 2-mmHg/second (Beevers et al 2001b; Petrie et al 1986).
- Stethoscope or Doppler and water soluble jelly. Do not use KY Jelly as this erodes the transducer (Parks Medical 2002).
- Clean (using water not alcohol) (Parks Medical 2002).
- Used according to manufacturer's guidelines.
- Refer to manufacturer's guidelines.
Ensure that the examiner has:
- Washed their hands before carrying out the procedure (Rationale 20) (hand hygiene guideline).
- Is appropriately trained and familiar with all of the above points and the points below (Rationale 19).
Explain procedure to child/young person (Rationale 21):
outline procedure briefly
warn of minor discomfort that may be caused
explain that the procedure may be repeated
Variability in BP can be caused by:
Time of day.
Season of year.
Sleeping (tends to be lower) (Beevers et al 2001a).
Defence Reaction/‘White Coat’ Hypertension – this can cause an increase in BP and tends to subside when the child young adult becomes accustomed to the procedure and the observer.
The child/young person should ideally be asked to sit quietly for three to five minutes and wait 30 minutes after having eaten, exercised, had a conversation, drunk any coffee or had a cigarette (Nolan & Nolan 1993)(Rationale 22).
Automated measurement of blood pressure
Very few monitors have been validated for paediatrics and those that have are not validated for children with high BP (www.bhsoc.org). For this reason they cannot be recommended in younger children with high blood pressures. (For more detail see appendix 5)
Care should be taken if an oscillometric device inflates and deflates repeatedly 'hunting' without displaying the BP; this can indicate the BP is either too low or high for the automated monitor to register (Lurbe et al 2009). If this occurs, a manual BP should be measured.
Automated devices tend to under-read at low BP and over-read very high BP.
Position the manometer
It should be:
Posture of patient:
- Ensure the child is comfortable in a warm environment (Rationale 28).
- Tight or restrictive clothing should be removed from the arm/leg (Rationale 29).
- Apply the cuff, ensure the internal bladder width encircles 90 to 100 per cent of the upper arm circumference and the length from the auxilla to the elbow. This should fit firmly and be well secured (Petrie et al 1986). The arrow on the cuff should be placed over the brachial artery.
- The lower edge of the bladder should be one centimetre above the tubing from the blood pressure cuff and should not cross the auscultatory area (Rationale 30). The exception to this would be children who need long cuffs for large arm circumference. If the cuff covers the brachial area the radial pulse should be used.
- The tubing may lie inferior (going down), superior (going up) or posterior (at the back) (Rationale 31).
- The arm should be well supported at the level of mid-sternum (Rationale 32).
- The first BP reading should be estimated by palpation.
- Palpate over artery, place the stethoscope/Doppler/fingers over the pulse. Do not press too firmly or touch the cuff (Rationale 33).
- Inflate the cuff over three to five seconds. When the pulse sound disappears this is your estimated BP. Now deflate the cuff quickly (Beevers et al 2001b; Petrie 1986)(Rationale 34).
- Place the Doppler/stethoscope just above the antecubital fossa where you will hear the maximal pulsation of the brachial artery in the arm (Rationale 35).
- Inflate the bladder once again steadily to a pressure of 30mmHg above the previously estimated systolic BP (McAlister & Straus 2001)(Rationale 36).
- Reduce the pressure at 2-3mmHg per second (Rationale 37). If you are using the Greenlight 300TM a green light appears on the bottom right hand side of the monitor indicating deflation speed is correct.
- The point at which the first repetitive, clear tapping sounds (Phase 1) first appear for at least two consecutive beats gives the SYSTOLIC BP (McAlister & Straus 2001).
- The point at which the repetitive sounds disappear (Phase 5) gives the DIASTOLIC BP (McAlister & Straus 2001). Note: a Doppler will not record the diastolic BP. If a diastolic BP is required, a stethoscope is required (Rationale 38).
- Then continue to completely deflate the cuff rapidly (McAlister & Straus 2001).
- Both measurements should be taken to the nearest 2mmHg (Beevers et al 2001b)(Rationale 39). A diastolic BP Phase 5 may not be present in some groups of children (children under 13 years old). For these the diastolic BP should be recorded at the point where muffling of the repetitive sounds is taken (Phase 4). This should be clearly documented as Phase 4.
- There may be a 'silent' or 'auscultatory gap' where sounds disappear shortly after the systolic phase is heard. This should be documented if it is noted – care must be taken to ensure that the systolic phase is heard and the return of the sounds after the gap are not thought to be the systolic BP. If the reading is difficult to ascertain – which is common in small, unsettled infants – it may be easier to find a second person to assist with the measurement (Rationale 40).
- If it is necessary to repeat the BP, the cuff should be allowed to fully deflate, then a minute should elapse before the next measurement is taken (Petrie et al 1986)(Rationale 41).
- Children who are found to be hypertensive on automated monitors should have their BP measured manually. The exception to this are ventilated/sedated children (Brennan 2012)(Rationale 42).
- The centre of the cuff bladder (usually labelled artery) should be placed over the brachial artery.
- Ensure the correct patient setting is set on the monitor (neonate, paediatric, adult) and press the start button as recommended by the manufacturers. Set the monitor for a single measurement or automatic measurement for the frequency required as recommended in the manufacturer's guide. The cuff should be reapplied frequently if regular BP monitoring is required (Rationale 43).
- Cuff (size chosen Diagram 1) should fit firmly and be well secured (Perloff, 1993). Avoid using arms that has an intravenous infusion or cannula in place (User Guide to M3046A 2001)(Rationale 44).
- The arm should remain still during the measurement (Rationale 45).
- If the BP readings are above the expected level for age and height and the child is calm and not in any discomfort during the procedure the BP measurement should be repeated three times, leaving at least one minute between readings. Make sure the cuff bladder size is correct and continue to monitor. If the readings obtained are consistently high a four limb BP should be measured. If the problem continues, manual BP measurement should be obtained (Rationale 46) (follow flow chart).
- If the child’s BP is to be monitored continually make sure the cuff is not wrapped too tightly around the limb (Rationale 47).
- If it is necessary to repeat the BP, the cuff should be allowed to fully deflate, then a minute should elapse before the next measurement is taken (Petrie et al 1986)(Rationale 48).
Recording a blood pressure
- The BP should be written down as soon as it is recorded (Rationale 43).
- The BP should be recorded with arrow tops pointing up – or as a Y with the arrows pointing down – but the tip of the point should be at the number.
- The arm in which the pressure is being recorded and the position of the subject should be noted, for example, left arm – sitting (Rationale 44).
- In children, the arm circumference and bladder size should be indicated.
- If the patient is anxious, restless or distressed, a note should be made with the BP (Perloff et al 1993; Beevers et al 2001b; Petrie et al, 1986)(Rationale 45).
Appendix 1: Blood pressure levels (PDF, 20 KB)
Appendix 2: Flow chart for BP measurement
Appendix 3: Quick guide to BP measurement
Appendix 4: Accurate cuff sizing (Diagram 1)
Appendix 5: Oscillometry (automated) methods of BP measurement in children can be problematic – the accuracy of several models used by many paediatric areas has known limitations (Lurbe et al 2009; Flynn 2012). Oscillometric devices calculate BP from the oscillations detected in the cuff – this determines the mean BP directly from the maximum point of oscillation – the systolic and diastolic are then calculated using an algorithm (Lurbe et al 2009). The problem with this method is that the oscillation in children is often short so the potential for erroneous measurements is increased significantly (Lurbe et al 1999), leading to an increased variability in measurements. It has been well documented that these devices do not function well in patients with arrhythmias, the elderly, dialysis patients and patients with reduced vascular elasticity such as diabetics (O’Brien et al 2001) In practice, children with hypertension appear to be a group at risk. Many of the above problems found in adults also apply to children with hypertension and critical illness. Very few monitors have been validated for paediatrics and those that have are not validated for children with high BP (www.bhsoc.org). For this reason they cannot be recommended in younger children with high blood pressures. Care should be taken if an oscillometric device inflates and deflates repeatedly 'hunting' without displaying the BP; this can indicate the BP is either too low or high for the automated monitor to register (Lurbe et al 2009). If this occurs, a manual BP should be measured (see the Measuring BP flow chart). Automated devices tend to under-read at low BP and over-read very high BP.
Rationale 1: Research suggests that many children can have a high BP of unknown origin (or primary hypertension), and this must be noted and followed up (National High Blood Pressure Education Group 2004; de Sweit & Dillon 1989).
Rationale 2: Hypertension can run in families (de Sweit 1986).
Rationale 3: Renal disease can cause an alteration in volume status and renin production (Edwards 1997).
Rationale 4: Hypertension is a common symptom of renal conditions (Rascher 1997).
Rationale 5: Cardiac disease can cause an alteration in BP due to altered cardiac contractility (Edwards 1997).
Rationale 6: To reduce the risks of diabetic kidney disease and eye disease (Adler et al 2000).
Rationale 7: Hypertension is common in pregnant women (Beevers et al 2001a).
Rationale 8: BP is an essential component of cardiovascular assessment (Derrico 1993).
Rationale 9: Changes in BP can indicate hypovolaemia, sepsis, shock, or be a side effect of anaesthetic drugs (Wong 2001).
Rationale 10: An altered BP can indicate that a change to treatment may be necessary or that action should be taken (for example indicate an altered fluid status during albumin infusion or a reaction to blood transfusion).
Rationale 11: To assess for pressure differences between arms, which may be more than 10mmHg in some hypertensive patients (McAlister & Straus 2001).
Rationale 12: Arterial lines are usually only used in critical care settings because of the associated risks with use, eg haemorrhage, thrombosis and infection (Clarke 1999; Roberts 2002).
Rationale 13: Because of greater accuracy and reproducibility.
Rationale 14: The Greenlight300TM is felt to be more accurate as it is self calibrated and easier to maintain than previous manometers.
Rationale 15: To prevent additional distress to the child by delayed procedure (National Heart, Lung & Blood Institute Task Force 1987).
Rationale 16: To ensure that it will provide an acceptably accurate measurement and meets recommendations. Literature has demonstrated that up to 50 per cent of BP measuring equipment is thought to be inaccurate (Nolan & Nolan 1993) and can result in the recording of an inaccurate BP (Petrie et al 1986).
Rationale 17: To ensure that the most accurate BP reading can be made and avoid 'cuff hypertension' (Beevers et al 2001a).
Rationale 18: Cuff size and positioning is crucial to an accurate BP measurement (de Sweit et al 1989).
Rationale 19: To minimise spread of infection.
Rationale 20: To minimise any potential error in BP recording (Nolan & Nolan 1993).
Rationale 21: To minimise the risk of anxiety which may result in a temporarily elevated BP (Beevers et al 2001a; Perloff et al 1993). The child/young person should be informed of the need for BP measurement (Petrie et al 1986). If the child is anxious the play in clinic ambulatory blood pressure monitoring is recommended (Urbina 2008).
Rationale 22: These variables can alter a BP (Nolan & Nolan 1993).
Rationale 23: To prevent observer error (Perloff et al 1993; Beevers et al 2001b).
Rationale 24: To prevent injury to the staff performing the blood pressure measurement.
Rationale 25: To ensure that the procedure is performed accurately and on the first attempt to prevent unnecessary repeating of the procedure and further distressing the child (Perloff et al 1993).
Rationale 26: BP centiles are recorded on children in the seated position (Petrie et al 1986) but, if the patient is lying down, the BP may read slightly lower (Beevers et al 2001a).
Rationale 27: BP can be significantly increased by the patient’s legs being crossed (Foster-Fitzpatrick et al 1999).
Rationale 28: To minimise the effect of extraneous influences which may temporarily alter the BP (Perloff et al 1993).
Rationale 29: To prevent recording an inaccurate BP (Thompson 1981).
Rationale 30: Contact of the stethoscope with the cuff tubing may produce artefactual sounds.
Rationale 31: To allow easy access to the auscultatory area (antecubital fossa) (Beevers et al 2001b).
Rationale 32: If the child’s arm is below heart level BP can be overestimated by 10mmHg and if above it can be underestimated by same amount (Petrie et al 1986).
Rationale 33: To avoid inaccuracies in BP measurement.
Rationale 34: To maximise the accuracy and reproducibility of the measurement (Petrie et al 1986).
Rationale 35: Prevents underestimation of systolic pressure by misreading Korotkoff 3 after auscultatory gap as Korotkoff 1 (Perloff et al 1993; Beevers 2001b).
Rationale 36: Slow inflation results in venous congestion (Nolan & Nolan 1993).
Rationale 37: Rapid deflation can result in recording errors (Nolan & Nolan 1993).
Rationale 38: A doppler will not pick up the diastolic BP because it only detects the acoustic waves moving towards the transducer as apposed to the sound.
Rationale 39: To avoid digit preference.
Rationale 40: To enable an accurate reading to be taken.
Rationale 41: To allow refilling of blood vessel.
Rationale 42: The manufacturers warn that clinical judgement should be used in the appropriateness of using an automated monitor on patients who are moving, shivering or convulsing, with cardiac arrhythmias and/or if the patient's BP is changing rapidly over a period of time (renal replacement therapy or fluid shifts), severe shock or hypothermia where blood flow to the peripheries is reduced, heart rate extremes (<40bpm->300bpm). Care must also be taken with obese patients as a thick layer of fat surrounding the arm dampens the oscillations coming from the artery, and accuracy is reduced (User Guide to M3046A 2001; American Heart Association; Atherosclerosis, Hypertension and Obesity in Youth; Committee of the Council on Cardiovascular Disease in the Young and the Council for High Blood Pressure Research).
Rationale 43: If the monitor inflation settings are too high this may cause considerable discomfort to the child and cause the BP to increase due to a pain response. Frequent repeated measurement can cause purpura, ischemia and neuropathy (User Guide to M3046A 2001), for this reason the BP cuff should be reapplied hourly and the skin observed for colour, warmth and sensitivity.
Rationale 44: To ensure that the most accurate BP reading can be made and avoid 'cuff hypertension' (National Heart, Lung and Blood Institute Task Force on Blood Pressure Control in Children 1987). The manufacturer's recommendations are not to measure BP on arms with infusions or cannula as there is an increased risk of tissue damage and extravasation (User Guide to M3046A 2001).
Rationale 45: Movement artefact is often responsible for falsely high readings or an inability for the monitor to register a reading, but this is not always the case. In this situation a manual BP should be taken.
Rationale 46: The BP readings on automated monitors do tend to be slightly higher than manual readings on normotensive children. On hypertensive children the variability seems to be significant. To date there are no automated monometers that have been successfully validated for use in hypertensive children in the UK.
Rationale 47: This may cause discoloration and even ischemia.
Rationale 48: To prevent venous congestion which would give an inaccurate BP on the second reading (Nolan & Nolan 1993).
Rationale 49: To prevent the measurement being forgotten.
Rationale 50: The same limb and cuff size should be used for repeated measurements to ensure consistency.
Rationale 51: Can cause a false high reading to be taken and, if not indicated as such, this reading could be considered as a true BP which may lead to instigation or inappropriate treatment. (Flynn et al 2012; Perloff et al 1993; Beevers et al 2001b; Petrie et al 1986).
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Document control information
Eileen Brennan, Nurse Consultant, Renal Unit
Trish Evans, Practice Educator, Renal Unit
Eileen Brennan, Nurse Consultant, Renal Unit
Clinical Practice Committee
First introduced: 25 February 2004
Date approved: 8 August 2013
Review schedule: Two years
Next review: 8 August 2015
Document version: 3.0
Replaces version: 2.0