MEASURES OF BP VARIABILITY,INSTABILITY,REACTIVITY
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’.
DAVIDSON’S PRINCIPLES AND PRACTICE OF MEDICINE 21ST ED
True BP vs Surrogate
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
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,
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
The monitor defines the maximal oscillations as mean arterial BP and then
uses an algorithm to calculate systolic and diastolic BP.
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%.
Indications for ABPM
Suspected white-coat hypertension (including in pregnancy)
Suspected masked hypertension (untreated subject with normal
clinic BP and elevated ABP)
Suspected nocturnal hypertension or no night time reduction in BP
Hypertension despite appropriate treatment
Patients with a high risk of future cardiovascular events (even if
clinic BP is normal)
Suspected episodic hypertension.
Ambulatory BP monitoring may also be useful for:
Titrating antihypertensive therapy
Hypertension detected early in pregnancy
Suspected or confirmed sleep apnoea
Syncope or other symptoms suggesting orthostatic Hypotension,
where this cannot be demonstrated in the clinic.
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.
Defined as a normal clinic blood pressure and a high ambulatory
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.
Global Leading Risks for Death
pressure > 115
Global Burden of Disease Study 2010 , Lancet 2012; 380: 2224–60
India- Soon Heading Towards Being
Lancet 2005;365:217-23; JHH 2004;18:73-8J 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
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.
Therefore, a good case can be made for using this technique in all
patients in whom hypertension has been newly diagnosed by
means of clinic blood-pressure measurements.