Ambulatory BP monitoring

AMBULATORY BLOOD
PRESSURE
MONITORING
Dr. Ankur Banik
PGT
Dept. Of General Medicine
BMCH

AMBULATORY BLOOD PRESSURE
MONITORING
 Blood Pressure is the lateral pressure exerted by
the flowing blood on the walls of the arteries.
 Hypertension , i.e, greater than normal BP, is one of
the most important contributors to morbidity and
mortality in general.
 BP depends on a number of factors (both intrinsic
and extrinsic) and a single value may not be the
true representation of the actual BP.

BP ELEVATION
MULTIPLICATION OF CV RISK
BP: Leading risk factor for Global
Burden of Disease (GBD, 2010)
HT is associated with:
 69% of first MIs
 74% of cases of CHD
 77% of first strokes
 91% of cases of HF
BP=blood pressure; HTN=hypertension; MI=myocardial infarction;
CHD=coronary heart disease; HF=heart failure.

Global Leading Risks
for Death
Systolic blood
pressure > 115
mmHg
Global Burden of Disease Study 2010 , Lancet 2012; 380: 2224–60

Meta-analysis of 61 prospective, observational studies*
1 million adults
12.7 million person-years
*Epidemiologic studies, not clinical trials of HTN agents.
BP, blood pressure; IHD, ischemic heart disease.
Lewington S et al. Lancet 2002;360:1903-1913.
BP REDUCTION IS CRITICAL THE LOWER, THE
BETTER
2 mm Hg
decrease in
mean SBP 10% reduction in
risk of stroke
mortality
7% reduction
in risk of IHD
mortality

BENEFIT OF BP CONTROL
10 mm Hg lower systolic BP is associated with
 50-60% lower risk of stroke death
 40-50% lower risk of death – CAD
 50% lower heart failure
GREATER BENEFIT IN OLDER AGES AND
AT HIGHER INITIAL BP READINGS

HYPERTENSION IN INDIA
MET-ANALYSIS OF 142 STUDIES (1950-2013)
 Overall Prevalence: 29.8%
Rural (%) Urban (%)
Prevalence 27.6 33.8
Awareness 25.3 42.0
Treatment 25.1 37.6
Control 10.7 20.2
Anchala R et al. J Hypertens. 2014 Jun;32(6):1170-7.

INDIA- HYPERTENSION CAPITAL
60.4
107.3
57.8
106.2
0
20
40
60
80
100
120
2000 2025
No.ofpeoplewithhypertension
inIndia(millions)
Men Women
Lancet 2005;365:217-23; JHHJ Assoc Physicians India 2007;55:323-4
At least 1 out of every 5 adult Indians has hypertension
Age > 20 yrs
Hypertension is responsible for 57% of all stroke deaths
and 24% of all CHD deaths in India

BLOOD PRESSURE MEASUREMENT
“The measurement of blood pressure is the clinical procedure of
greatest importance that is performed in the sloppiest manner.”
Kaplan N. M. Amer J Hypertension 1998: 11: 134-6

BP VARIABILITY
 BP normally fluctuates during the day and varies
from day-to-day.
 Pronounced fluctuations in BP can occur over short
/ long-term.
 Episodic Hypertension is common:
 In TIA patients, 12% had stable HT, 69% had episodic
HT (some SBP readings ≤140 mmHg, some >140
mmHg)
 BPV is difficult to measure in routine clinical
practice: no clearly defined or widely adopted
diagnostic definitions or treatment goals

BP REACTIVITY
 Defined as the response to environmental
stressors, usually quantitated as responses to
standardized laboratory stressors.
 Hot reactors –individuals with increased reactivity.
 Difficult to quantitate – reactivity differs from
stressor to stressor and even upon retesting with
same stressor.
 Suspected to be predictive of future development of
hypertension and CV risk – studies have not found
this to be true.

BP LABILITY
 Characteristic of human BP.
 No clear definition that differentiates normal from
abnormal lability.
 Labile hypertension – widely used – lacks an
accepted definition and is more of a clinical
impression rather than a specific diagnosis.
 Patients experience transient but substantial
increases in BP.
 Likely due to sympathetic activation.
 BP usually falls without intervention.
 Risk of hypertension in future but no role of pre
treatment.

TYPES OF BP VARIABILITY
DETERMINANTS AND PROGNOSTIC RELEVANCE
Pronounced fluctuations in BP can occur over short- and long-term
observation periods
Parati et al. Nat Rev Cardiol 2013;10:143-155

MEASURES OF BP
VARIABILITY,INSTABILITY,REACTIVITY

BPV DIFFERS IN EXTENT BETWEEN INDIVIDUALS
Rothwell PM. Lancet 2010;375:938-948
Patient 1 with lower BPV Patient 2 with higher BPV
Weeks
40
60
80
100
120
140
160
180
200
220
Bloodpressure
(mmHg)
1 2 3
SBP
DBP
40
60
80
100
120
140
160
180
200
220
Bloodpressure
(mmHg)
1 2 3
Weeks
Higher
mean BP
overall

HYPERTENSION- CAN IT BE GENERALISED?
 High BP is a trait as opposed to a specific disease
and represents a quantitative rather than a
qualitative deviation from the norm.
 Any definition of hypertension is therefore arbitrary.
 Thus a practical definition of hypertension is ‘the
level of BP at which the benefits of treatment
outweigh the costs and hazards’.

TRUE BP VS SURROGATE BP
 Any clinical measurement of blood pressure may be
regarded as a surrogate measure for the “TRUE”
blood pressure of the patient, which may be defined
as the mean level over prolonged periods.
 Two techniques have been developed to improve
the estimate of true blood pressure — ambulatory
monitoring and home monitoring (or self-
monitoring).

ABPM
 Ambulatory blood
pressure (ABP)
monitoring involves
measuring blood pressure
(BP) at regular intervals
(usually every 20–30
minutes) over a 24 hour
period while patients
undergo normal daily
activities, including sleep.

 The portable monitor is
worn on a belt connected
to a standard cuff on the
upper arm .
 When complete, the
device is connected to a
computer that prepares a
report of the 24 hour, day
time, night time, and sleep
and awake (if recorded)
average systolic and
diastolic BP and heart
rate.

ABPM – MEASURING METHOD
 Ambulatory BP monitors use cuff oscillometry.
 The cuff is inflated until the pressure occludes flow
within the brachial artery. As the pressure is
released, blood begins to flow causing fluctuations
(oscillations) in the arterial wall that are detected by
the monitor. These oscillations increase in intensity
then diminish and cease when blood is flowing
normally.
 The monitor defines the maximal oscillations as
mean arterial BP and then uses an algorithm to
calculate systolic and diastolic BP.

INTERPRETATION OF ABPM
 Unique data provided by ABPM include:
 24-hour average blood pressure (BP)daytime
(awake) BP
 Night time (asleep) BP
 Systolic blood pressure load
 Diastolic blood pressure load
 Nocturnal dipping of the BP

 Reference ‘normal’ ABP values for non pregnant
adults are:
 24 hour average <115/75 mmHg (hypertension
threshold 130/80 mmHg)
 Day time (awake) <120/80 mmHg (hypertension
threshold 135/85 mmHg)
 Night time (asleep) <105/65 mmHg (hypertension
threshold 120/75 mmHg).

ABPM – DIAGNOSTIC THRESHOLDS
Category 24hr
systolic/di
astolic
(mm Hg)
Daytime
(mm Hg)
Nighttime
(mm Hg)
NORMAL <115/75 <120/80 <105/65
HTN >130/80 >135/85 >120/75

 Ambulatory BP values above ‘normal’ and below
thresholds for hypertension are considered ‘high
normal’.
 Night time (sleeping) average systolic and diastolic
BP should both be at least 10% lower than day time
(awake) average.
 Blood pressure load (percentage of time that BP
readings exceed hypertension threshold during 24
hours) should be <20%.

WHITE COAT HYPERTENSION
 White-coat hypertension is defined as a clinic
blood pressure of 140/90 mm Hg or higher on at
least three occasions, with at least two sets of
measurements of less than 140/90 mm Hg in non-
clinic settings, plus the absence of target-organ
damage.

 ANXIETY- MAIN CAUSE
 Having the BP in the office taken by a nurse or
technician, rather than the clinician, may minimize the
white coat effect.
 In patients diagnosed as being hypertensive on a first
visit to a new clinician, there is a mean 15 and 7 mmHg
fall in the systolic and diastolic BP, respectively, by the
third visit , with some patients not reaching a stable
value until the sixth visit .
 It is recommended that a patient with mild to moderate
elevation in BP should not be diagnosed with
hypertension unless the BP remains elevated after three
to six visits, unless there is evidence of ongoing end-
organ damage
AMBULATORYBPMONITORING-SHOULD
ITBEROUTINE?

ITBEROUTINE?

 In cross-sectional studies, the prevalence of white
coat hypertension ranges from 10 to more than 20
percent, and appears to be higher in children and
the elderly .
 White coat hypertension can also be seen in
patients with apparently resistant hypertension.
 The likelihood of normal ambulatory pressures is
low (less than 5 percent) in patients with office
diastolic pressures ≥105 mmHg.
 In one study of nearly 500 treated hypertensive
patients (over 60 percent on three or more
antihypertensive agents), 37 percent had normal
BP on ABPM.
ITBEROUTINE?

PROGNOSIS OF WHITE COAT
HYPERTENSION
 The cardiovascular risk associated with white coat
hypertension may be slightly higher compared with
persistent normotension but well below the risks
associated with either masked or sustained
hypertension.
 In a population-based cohort of 2051 adults who
underwent office, home, and ambulatory blood pressure
measurements, those with white coat hypertension had
a significantly higher rate of all-cause mortality during 16
years of follow-up as compared with persistent
normotension (19.7 versus 6.4 percent).
 Patients with white coat hypertension are also at high
risk for developing sustained hypertension.
ITBEROUTINE?

 Optimal approach to patients with white coat
hypertension is uncertain.
 Careful monitoring is indicated for the possible
development of worsening hypertension or of end-
organ damage, while the patient is encouraged to
modify unhealthy lifestyle habit.
ITBEROUTINE?

MASKED HYPERTENSION
 Defined as a normal clinic blood pressure and a
high ambulatory blood pressure.
 This condition is the reverse of white-coat
hypertension.
 The clinic blood pressure of patients with masked
hypertension may underestimate the risk of
cardiovascular events.

MASKED HYPERTENSION
 As many as 10 to 40 percent of patients who are
normotensive by conventional clinic measurement
are hypertensive by ABPM.
 This phenomenon is called masked hypertension
or isolated ambulatory hypertension.
 It has only been identified by screening clinical
studies, since patients who are normotensive by
office readings do not typically undergo ambulatory
monitoring.
ITBEROUTINE?

MASKED HYPERTENSION
 Masked hypertension has been associated with an
increased long-term risk of sustained hypertension
and cardiovascular morbidity .
 Because of the risk associated with masked
hypertension, ambulatory blood pressure
monitoring should be considered in patients
referred for possible hypertension.
ITBEROUTINE?

BLOOD PRESSURE LOAD
 The BP load is defined as the percentage of
ambulatory systolic and diastolic pressures
exceeding 140 mmHg and 90 mmHg during the
daytime, and 120 mmHg and 80 mmHg during
sleep.
 The overall BP load may also be a determinant of
cardiovascular risk.
 Studies in untreated hypertensive subjects suggest
that the likelihood of developing cardiac
abnormalities is markedly increased when the daily
BP load is 40 percent or more.
ITBEROUTINE?

NOCTURNAL BLOOD PRESSURE AND
NONDIPPERS
 A cohort study of 7458 patients in six countries from
Europe, Asia, and South America found that both
daytime and night time BP predicted all
cardiovascular events.
 Night time blood pressure, adjusted for daytime
BP, predicted total, cardiovascular, and non
cardiovascular mortality.
 In contrast, daytime blood pressure, adjusted for
blood pressure measured during sleep, only
predicted noncardiovascular mortality
ITBEROUTINE?

NONDIPPERS
 The average nocturnal BP is approximately 15
percent lower than daytime values in both normals
and hypertensive patients.
 Failure of the BP to fall by at least 10 percent
during sleep is called nondipping.
 The underlying mechanisms of nondipping are
unknown, but intrinsic renal defects may contribute.
 There is also some evidence suggesting that
melatonin plays a role.
ITBEROUTINE?

NONDIPPERS
 Independent of the degree of hypertension,
nondipping is a risk factor for the development of
left ventricular hypertrophy (LVH), heart failure and
other cardiovascular complications .
 Extreme "dipping" (eg, >20 percent nocturnal
decline in BP) and a large morning increase in BP
are also potentially deleterious .
ITBEROUTINE?

NONDIPPERS
 Nondipping has also been associated with
microalbuminuria and faster progression of
nephropathy in patients with diabetes mellitus.
 Nondipping may be a risk factor for decline in
glomerular filtration rate, and ESRD and death
among patients with chronic kidney disease.
 The presence of sleep apnea should also be
considered in nondippers.
ITBEROUTINE?

NOCTURNAL HYPERTENSION
NIGHTTIME BP ≥120/70 MMHG (ABPM)
 Normally BP ↓ses by 10-20% at night (Dipping)
 Non-dipping / Reverse Dipping:
 ↑ risk of organ damage (brain, heart, kidney)
 ↑ CV events and mortality
Range of BP Dipping Class
<0% Reverse Dipping
≥0%, <10% Non-Dipping
≥10%, <20% Dipping (Normal pattern)
≥20% Extreme Dipping
JSH. Hypertension Research. 2009;32:70-7.

SLEEP-TIME BLOOD PRESSURE
 Sleep time BP has been said to be associated with new
onset T2DM.
 In a study examining 2,656 individuals of higher
nocturnal blood pressure levels,who did not have
diabetes at the beginning of the study, After an average
of 5.9 years of follow-up, 190 participants had
developed T2 DM.
 This first study suggested to the researchers that
lowering sleep-time blood pressure could be a novel
method for reducing the risk of new-onset diabetes.
 In another study Diabetes risk fell by 57% in patients
taking anti hypertensive medication before bed.

PROGNOSTIC VALUE OF ABPM
ITBEROUTINE?

ITBEROUTINE?
PREDICTION OF CARDIOVASCULAR RISK

PROGRESSION OF KIDNEY DISEASE
 A cohort study of 217 patients suggested that
elevated blood pressure by ABPM correlated more
strongly with progression to end-stage renal
disease (ESRD) than clinic systolic blood pressure.
 In addition, night ambulatory blood pressure was a
strong predictor of the composite outcome of death
and ESRD
ITBEROUTINE?

INDICATIONS FOR ABPM
In accordance with published practice guidelines and
expert panel recommendations, ambulatory
monitoring should be considered in the following
circumstances :
 Suspected white coat hypertension
 Suspected masked hypertension
 Suspected episodic hypertension
 Hypertension resistant to increasing medications
 Hypotensive symptoms while taking
antihypertensive medications
 Autonomic dysfunction
ITBEROUTINE?

OTHER POTENTIAL INDICATIONS
 To establish nondipper status or nocturnal
hypertension
 Large variations in self-measured blood pressure
values
 To evaluate whether antihypertensive therapy is
moderating the early morning blood pressure surge
 Elevated office blood pressure in pregnant women,
with preeclampsia suspected
 Patients with a high risk of future cardiovascular
events (even if clinic BP is normal)
ITBEROUTINE?

ABPM Recommended in High Risk Groups
✓ Ongoing antihypertensive treatment
✓ High-normal BP (130-139 / 85-89 mmHg)
✓ Smoking / DM / Obesity / Metabolic syndrome / CVD
✓ ↑sed drinking / stress / physical activity / heart rate
✓ Abnormal orthostatic changes in the BP
✓ Organ damage (LVH, ↑ carotid intima-media thickness)
Clinical Suspicion is Essential in these high-risk patients
JSH. Hypertension Research. 2009;32:70-7.

INDICATIONS FOR ABPM
ITBEROUTINE?

INFLUENCE ON THERAPY OF
HYPERTENSION
 Therapeutic decisions can be made according to
the ambulatory blood pressure (BP) findings.
 Ambulatory or self-recorded home readings may
detect the early morning BP surge that may
contribute to the increased incidence of sudden
death, myocardial infarction, and stroke in the early
morning hours.
ITBEROUTINE?

HYPERTENSION
 Modulation of this early morning surge in BP may
not occur with supposedly long-acting, "once-daily"
agents which do not provide 24-hour coverage.
 Such drugs, including atenolol or enalapril, may
lose much of their effect during the early morning
hours, and therefore may need to be taken twice
daily.
 Preferably, long-acting medications with effects
that truly last for 24 hours should be substituted.
ITBEROUTINE?

HYPERTENSION
 In those with nocturnal hypertension or nondipping,
ABPM may helps determine the best timing of
administration of antihypertensive agents.
 In one study, valsartan taken before bedtime
reestablished the nocturnal reduction in BP.
ITBEROUTINE?

HOME BP MEASUREMENTS
 In view of the cost and limited availability of
ambulatory monitoring, increasing attention is being
given to home monitoring with inexpensive semi-
automatic devices.
 Casual blood pressure (BP) measurements taken
at home or work correlate more closely with the
results of 24-hour or daytime ambulatory monitoring
than with the BP taken in the clinician's office .
 Home BP measurements are more predictive of
adverse outcomes (eg, stroke, end-stage renal
disease) than clinic blood pressures.
ITBEROUTINE?

GUIDELINES FOR MEASURING HOME
BP
 While seated, the patient should take two
measurements (separated by one to two minutes) in the
morning and in the evening (ie, four measurements per
day) for at least three, and preferably seven,
consecutive days. These measurements should be
recorded.
 Measurements from the first day should be discarded;
the home blood pressure is defined as the average of all
remaining measurements.
 In stable hypertensive patients with controlled BP, this
same procedure of 12 to 14 measurements taken over
one week should be repeated approximately every three
months to determine whether the BP remains controlled
.
ITBEROUTINE?

IS HBPM EQUIVALENT TO ABPM?
Measurement
Method
Ambulatory
(ABPM)
Home
(HBPM)
Clinic (Office)
Measurement
Supervision + - / + +
BP Patterns
Daytime;
Nighttime; 24 hr.
Daytime only In clinic only
BP Variability
24 hr. (intraday);
Visit-to-visit
Day-to-day Visit-to-visit
Prediction of
Outcome
Best; nighttime
HT crucial
Superior to Clinic
BPM
Standard
measure
Guidance to
Drug treatment
Most complete;
24 hr. control
Limited; better
than Clinic BPM
Limited and poor
Improving
Compliance
Maybe helpful Best evidence Minor influence
O'Brien E et al. J Hypertens. 2013 Sep;31(9):1731-68.

SUMMARY AND RECOMMENDATIONS
 The diagnosis of hypertension based upon ABPM
depends upon the time span over which it is
interpreted :
 A 24-hour average above 135/85 mmHg
 Daytime (awake) average above 140/90 mmHg
 Nighttime (asleep) average above 125/75 mmHg
 Cardiovascular complications correlate more
closely with 24-hour or daytime ABPM than with the
office BP.
ITBEROUTINE?

SUMMARY AND RECOMMENDATIONS
 ABPM may facilitate achieving blood pressure
control and reduce unnecessary treatment.
 ABPM should always be considered when
indicated.
 Conditions like masked hypertension, white coat
hypertension, nocturnal hypertension and others
also cannot be assessed properly without ABPM.
 Self-recorded home BP measurements are an
excellent alternative if ABPM is not available or cost
is a concern.
ITBEROUTINE?

CONCLUSION
 Ambulatory monitoring can be regarded as the gold
standard for the prediction of risk related to blood
pressure, since prognostic studies have shown that
it predicts clinical outcome better than conventional
blood-pressure measurements.
 In spite of the high cost, ABPM should be offered to
more and more patients to more effectively deal
with the menace of hypertension.

Ambulatory BP monitoring

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