Transcript Ambulatory blood pressure monitoring in children

By
Shaimaa Sayed
 Introduction
 Definition
 Technique
 Values
 Problems
 Other
methods for assessment of blood
pressure
 Ambulatory blood pressure monitoring and
abnormalities of vascular structure.

The assessment of blood pressure is challenging in
children, especially in very young individuals, due to
their variable body size and lack of cooperation.

So, it needs to be measured repeatedly on regular clinic
and extra-clinic visits, to establish if it is truly elevated.

Ambulatory blood pressure monitoring (ABPM) is an
important tool in evaluating pediatric hypertension.

It is also more reliable than casual blood pressure by
providing multiple readings over time.
Definition:

It is a non-invasive procedure in which a portable
blood pressure device, worn by a patient, periodically
records blood pressure over a specified period of time,
usually 24 hours.

It measures the average systolic and diastolic blood
pressure during both patient’s regular daily activities
and sleep.

It typically yields 40–80 readings.

It measures the proportion of time that the systolic and
diastolic blood pressure is abnormally high.

The percent of number of values that exceeding the
upper limit of normal range, is known as blood
pressure load.

Abnormalities of ambulatory blood pressure predict the
development of hypertensive end-organ damage,
specifically left ventricular hypertrophy.
Technique:

The patient has a blood pressure cuff with suitable size.

The patient wears the cuff and a small electronic device
which can be worn in a pocket.

The device prompts the cuff to inflate every 20 minutes
during the day and every 30 minutes at night to
measure blood pressure and also records the readings.

The patient wears the monitor for 24 hours.
Technique:

Patients are advised to avoid heavy physical activity
during the study.

The monitor is then returned to the clinic and the
readings are downloaded for analysis.

The nephrologist reviews these results with the patient
and family.
Values:

ABPM is the best way to differentiate true
hypertension from white coat hypertension.

Up to 30% of children with elevated clinic blood
pressure actually have white coat hypertension.

So, they may be spared from unnecessary therapy.

But, these children are at increased risk for true
hypertension and cardiovascular disease, so annual
ABPM may be necessary.
Values:

Masked hypertension is the phenomenon of elevated
ambulatory blood pressure when clinic blood pressure
is normal.

Children with masked hypertension had increased risk
of left ventricular hypertrophy.

Also, ABPM can decrease the misdiagnosis of clinic
hypertension from improper measurement technique,
incorrect cuff size and patient anxiety.
Values:

It also allows measurement of changes in blood
pressure variability and nocturnal dipping.

It can be used to classify hypertension.
Classification
Office BP
Mean
ambulatory SBP
or DBP
SBP or DBP
load
Normotension
<90th percentile
<1.28 SDS
<95th percentile
<1.65 SDS
<25 %
White coat
hypertension
≥95th percentile
≥1.65 SDS
<95th percentile
<1.65 SDS
<25 %
Pre-hypertension
≥90th percentile
<95th percentile
≥1.28 SDS
<1.65 SDS
or >120/90 mmHg
≥25 %
Masked
hypertension
<95th percentile
<1.65 SDS
>95th percentile
>1.65 SDS
≥25 %
Ambulatory
hypertension
>95th percentile
>1.65 SDS
>95th percentile
>1.65 SDS
25-50 %
Severe ambulatory >95th percentile
hypertension
>1.65 SDS
>95th percentile
>1.65 SDS
>50 %
Values:

It can be used to differentiate primary from secondary
causes of hypertension in children.

Daytime diastolic blood pressure load >25% or asleep
systolic blood pressure load >50% are both highly
specific for diagnosing secondary hypertension in
children.

It is frequently used to evaluate the effects of antihypertensive therapy.

It can be used to evaluate duration of action of
medications and assess patient compliance.
Problems:

It can only be reliably performed and interpreted in
children older than 5 years of age, although there have
been successful trials to use it on younger children .

The normative values for ABPM were obtained on
healthy European children, and some concerns have
been raised that these norms may not apply to other
populations.

Its device is prone to measurement errors if the device
software is not properly maintained or updated.

The definition of the nighttime period on ABPM can be
problematic.
Blood pressure variability and
rhythmicity

The sympathetic nervous system plays an important
in the regulation of blood pressure.

This is including the development and maintenance of
sustained hypertension, by a chronically elevated
central sympathetic tone in children.

Increased blood pressure variability may be associated
with the progression of chronic kidney disease.

Children with chronic kidney disease and uncontrolled
hypertension have higher systolic and diastolic blood
pressure variability.

Children with daytime SBP increased variability had a
strong association with the left ventricular hypertrophy.

Moreover, there is evidence that an increased blood
pressure variability in childhood is predictive of adult
hypertension and early onset of atherosclerosis.
 Short-term
variability:
Beat-to-beat blood pressure variability.

Long-term variability:
Day-to-day blood pressure variability.
Visit-to-visit blood pressure variability.
Type
Beat-to-beat BP
variability
Method
Comment
Continuous BP short-term, measured
by invasive intraarterial BP
Day-to-day BP
Home BP
Long-term, measured
variability
by SD of BP readings
Visit-to-visit BP
Office BP
Long-term, measured
variability
by SD of BP readings
Ambulatory (24-h BP) ABPM
Short-term, measured
variability
by SD of BP readings
on ABPM

The etiology of increased blood pressure variability is
multifactorial.

The short-term variability (beat-to-beat) is associated
with increased sympathetic nervous system activity,
behavioral and emotional factors.

The long-term variability (day-by-day, visit-to-visit)
results from decreased arterial compliance, improper
dosing of antihypertensive medications and noncompliance to treatment .

Blood pressure has a circadian rhythm or 24 hours
rhythm.

It means that the blood pressure reaches its highest
values during the awake time and then decrease to its
lowest values during sleep (nocturnal dipping) in
healthy individuals.

But, it was observed that significant alterations
(absence of nighttime dipping)occur in children with
hypertension and chronic kidney disease.

Nocturnal administration of anti-hypertensive
medication can restore a normal dipping and
significantly reduced cardiovascular morbidity and
mortality .
 Office
blood pressure measurement.
 Home
blood pressure measurement.
Method
Measured parameter
Comment
Auscultatory Auscultatory phenomena (Korotkoff •Reference method for BP assessment
sounds) are caused by turbulent flow •Operator dependent
when the cuff pressure is less than
the SBP (1st sound) and greater than
the DBP (last sound)
Automated
Oscillations of arteries, mean arterial •Less operator dependent
pressure is measured, the SBP and
•Widely used
DBP are calculated by the device
•Relies on device software
software
ABPM
Measurement of the BP during 24
hours including awake and asleep
periods
•BP level during 24 h, awake and asleep
periods
•BP dipping
•BP load
•Classification and staging of hypertension
•Correlates with target organ damage and
progression of chronic kidney disease
20 patients on regular hemodialysis for at least 6
months.
 Age range from 5 to 13 years old.
 9 females and 11 males.
 5 patients did not complete the nighttime measurement.
 Daytime SBP variability is high in 3 patients, DBP
variability is high in 4 patients.
 Nighttime DBP variability is high in one patient.


Degree of nocturnal fall (nocturnal dipping):
Systolic and diastolic : 8 non-dipper, 5 night-peaker.
Ambulatory blood pressure
monitoring and abnormalities of
vascular structure in hypertension
Vascular
structure
Arterial
stiffness
Endothelial
function
Venous
function

Ultrasound B-mode imaging is used to measure
combined intima and media thickness (cIMT).

The carotid artery is the most widely imaged (most
accessible and easy).

IMT correlated with higher daytime SBP index
(measured with ABPM ), which indicates more severe
hypertension.

Children with CKD were found to have a thicker cIMT
which becomes higher with the increased severity of
kidney disease.

M-mode evaluation of the common carotid artery provides
high quality images of the maximal (systolic) and minimal
(diastolic) diameters for the calculation of carotid stiffness.

Increased carotid stiffness was found in pre-hypertensive
young people before progression to sustained hypertension.

Similar to data on IMT, higher carotid stiffness in dialysis
patients than patients with mild CKD.

After renal transplant, these abnormalities remain and
correlate with higher blood pressure measured with ABPM.
Non-ultrasound methods:
 Cuff-based pressure device that measures resting brachial
artery distensibility.

Pulse wave velocity measures the speed at which the bolus
of blood travels along the arterial tree.

Augmentation index, which demonstrates features of central
arterial stiffness and is high in children with CKD .

Ambulatory arterial stiffness index is another parameter
calculated from a 24-h ABPM as 1 minus the slope of the
regression of the 24-h SBP readings on the DBP readings.

It is the ability of the endothelium to respond to stress.

Measured by ultrasound-based brachial flow-mediated
dilation.

It is low in children with CKD and post-renal transplant.

Its lowest levels in young people on dialysis.

Discomfort occurs with inflating a blood pressure cuff on
the forearm for 5 minutes to induce the ischemic stimulus.

No difference between hypertensive patients
and controls in terms of venous function.

But higher venous pressure may be in the arms of
hypertensive patients and greater reduction in venous
compliance.

Ambulatory blood pressure monitoring can be used for
the diagnosis of hypertension as a cost-effective, safe,
painless, non-invasive and accurate tool.

The assessment of blood pressure variability and
rhythmicity is important in the choice and timing of
antihypertensive therapy.

There is a relationship between blood pressure
variability and the development of target organ
damage.
 ABPM
should be considered in all children at risk
for developing hypertension to apply preventive
and therapeutic strategies early to avoid long term
morbidity and mortality.

As, hypertension is one of the common causes of
cardiovascular morbidity and mortality.

So, assessment of vascular structure and function is
very important.

Awazu M. Epidemiology of Hypertension in Children. In:
Pediatric Nephrology. Avner ED, Harmon WE, Niaudet P,
Yoshikawa N, Emma F and Goldstein SL, Springer 2016:
1907-1926.

Feber J and Litwin M. Blood pressure assessment-from BP
level to BP variability. Pediatr Nephrol 2016 ; 31:1071–
1079.
Flynn J, Hayman L, McCrindle W and Zachariah J.
Ambulatory Blood Pressure Monitoring in Children and
Adolescents.
http://hyper.ahajournals.org
Updated: December 20, 2013, accessed October 21, 2015.
Urbina EM. Abnormalities of vascular structure and
function in pediatric hypertension. Pediatr Nephrol 2016;
31:1061–1070.

