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Blood pressure - ambulatory monitoring in children

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Scope of Guideline

This guideline is intended for use by paediatricians and cardiologists in order to standardise the setup and reporting of ambulatory blood pressure monitoring in children.

Referrals to Starship Paediatric Nephrology Service

Paediatricians and cardiologists can send a standard referral letter outlining the suspected clinical problem, results of investigations, blood pressure measurements, current growth parameters (weight and height) as well as birth parameters to the Starship Paediatric Nephrology Service for triaging.

What is ambulatory blood pressure monitoring?

Recording of multiple BPs over a 24 hour period in the patient's normal environment reduces potential for transient stress (white coat) induced rises in blood pressure and it allows the evaluation of changes in 24 hour circadian pattern of BP.

Equipment

Most validated equipment are oscillometric devices. These devices have a lower percentage of erroneous readings than ascultatory ones and are easier to set up, less likely to record artifacts.

Normative data is based on oscillometric devices (Soergel 1997, Wuhl 2002). There are many devices available, but few have been validated for use for children by American Advancement for Medical Instruments or the British Hypertension Society protocols. A list of devices can be accessed from http://www.dableducational.org/

Setting up equipment

In general, children younger than 5-6 years of age cannot tolerate ABPM for a full 24 hour period.

Frequency of measurement varies between 15-30 minutes for daytime, every 20-60 minutes for night time: Recommend 20 minute intervals during the day time and 60 minutes overnight.

Activity recording with blood measurements is required by asking the parents or the child (if old enough) to keep a diary of activities. Not every activity needs to be recorded but major changes, e.g. meal times, watching TV, timing of medications.

  • Continue normal activities but avoid contact sports, vigorous exercise
  • Cuff applied to non-dominant arm 
  • Hold cuff arm still during actual measurements

Technical adequacy of a blood pressure profile

At least 80% of recordings must have been successfully measured in a 24 or 48 hour period. At least one valid measurement per hour during overnight.

Interpretation of ambulatory blood pressure recordings

The following elements must be included

  • Technical adequacy of 24 hour profile
  • Note of 95th centile limits for day/awake and night/sleep for height and gender of patient. If patient is 135cm tall, use limits for 130cm
  • These limits are entered into the monitor software before the statistical analysis is undertaken
  • Review average 24 hour, day time and night time systolic and diastolic BP 
  • Review percentage of readings above the 95% centile for systolic and diastolic . This is the BP load for the patient. 
    - BP load <25% if normal
    - BP load >50% is indication of moderately severe hypertension and correlates with increased left ventricular mass and
       LVH.
  • Review night time dipping. Both systolic and diastolic BP should dip more than 10% overnight. 
  • Review average heart rates during day and night time -is there a fall?

Note: ABPM readings by oscillometric devices are higher than resting BP by auscultation.

An example of an ambulatory blood pressure summary

ambulatory summary

Indications for ambulatory blood pressure monitoring

  • Confirming the diagnosis of hypertension
    • To determine whether true hypertension or white coat hypertension exists
    • Assess presence of masked hypertension
  • Assess blood pressure variability
    • Assess dipping status
    • Assess severity and persistence of high BP 
  • Evaluate effectiveness of drug therapy
    • Assess apparent drug resistant hypertension
    • Assess whether symptoms are due to drug related hypotension
  • Evaluate BP more accurately in chronic paediatric conditions - liver, kidney, heart transplants, autonomic dysfunction, suspicion of catecholamine induced tumour

Some conditions in which nocturnal hypertension is present

  • autonomic neuropathy
  • Cushing's syndrome 
  • chronic renal failure
  • phaeochromocytoma
  • renal transplantation
  • mineralocorticoid excess
  • accelerated hypertension
  • cardiac transplantation
  • corticosteroids (↑ catecholamine sensitivity)

Effect of obesity on ambulatory blood pressure

  • All parameters of 24 hour ABP significantly higher in obese than in lean patients
  • Less night time dipping
  • Higher heart rate in obese
  • BMI positively correlates with ABP parameters

Normative data

  • German dataset (Soergel, Wuhl) only normal reference values
  • 4th Task Report values should not be used as measurements obtained by auscultation on resting subjects, no night time readings - not applicable to ambulatory individuals.

Oscillometric mean ABP values in healthy children ( J Pediatr 1997;130:178-84)

Oscillometric mean ABP values

References

http://hyper.ahajournals.org/content/52/3/433.full

Wuhl E. Hypertension. 2003 Nov;21(11):2205-6.

Flynn JT. Hypertension. 2014;63:1116-1135;

Pediatric hypertension 2nd ed. Ed Flyn JT, Ingelfinger JR, Portman RJ Humana Press 2011

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Document Control

  • Date last published: 20 July 2015
  • Document type: Clinical Guideline
  • Services responsible: Paediatric Nephrology
  • Owner: William Wong
  • Editor: Greg Williams
  • Review frequency: 2 years

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