Cardiovascular Journal of Africa: Vol 25 No 6 (November/December 2014)

CARDIOVASCULAR JOURNAL OF AFRICA • Volume 25, No 6, November/December 2014

AFRICA

289

apply to both clinic and self-measurement of BP. Failure

to follow these guidelines leads to significant errors in BP

measurement. BP should be recorded using an approved and

calibrated electronic device or mercury sphygmomanometer

(Table 2). Repeat measurements should be performed on at least

three separate occasions within four weeks unless BP is

≥

180/110

mmHg.

Self- and ambulatory measurement of BP

Self BP measurement (SBPM) and ambulatory BP measurement

(ABPM) are recommended in selected circumstances and target

groups:

•

suspected white-coat HTN (higher readings in the office

compared with outside) or masked HTN (normal readings in

office but higher outside)

•

to facilitate diagnosis of HTN

•

to guide antihypertensive medication, especially in high-risk

groups, e.g. elderly, diabetics

•

refractory HTN

•

to improve compliance with treatment (SBPM only).

Masked HTN should be suspected if, despite a normal BP in the

clinic, there is evidence of target-organ damage.

All devices used for SBPM and ABPM should be properly

validated in accordance with the following independent websites:

http://afssaps.sante.fr

In general, only upper-arm devices are recommended, but

these are unsuitable in patients with sustained arrhythmias. For

SBPM the patient should take two early morning and two late

afternoon/early evening readings over five to seven days, and

after discarding the first day readings, the average of all the

remaining readings is calculated.

Wrist devices are recommended only in patients whose arms

are too obese to apply an upper arm cuff. The wrist device needs

to be held at heart level when readings are taken.

The advantages of SBPM measurement are an improved

assessment of drug effects, the detection of causal relationships

between adverse events and blood pressure response, and

possibly, improved compliance. The disadvantages relate to

increased patient anxiety and the risk of self-medication.

ABPM provides the most accurate method to diagnose

HTN, assess BP control and predict outcome.

Twenty-

four-hour ABPM in patients with a raised clinic BP reduces

misdiagnosis and saves costs.

Additional costs of ABPM were

counterbalanced by cost savings from better-targeted treatment.

It can also assess nocturnal BP control and BP variability, which

are important predictors of adverse outcome. However the

assessment is limited by access to ABPM equipment, particularly

in the public sector, and impracticalities of regular 24-hour

ABPM monitoring.

The appropriate cut-off levels for diagnosis of HTN by

SBPM and ABPM are listed in Table 3.

Automated office BP measurement

Despite efforts to promote proper techniques in manual BP

measurement, it remains poorly performed. Automated office

BP measurement offers a practical solution to overcome the

effects of poor measurement, bias and white coating.

It is

more predictive of 24-hour ABPM and target-organ damage

than manual office BP measurement. Six readings are taken

at two-minute intervals in a quiet room. The initial reading is

discarded and the remaining five are averaged. The appropriate

cut-off level for HTN is 135/85 mmHg.

CVD risk stratification

The principle of assessing and managing multiple major risk

factors for CVD is endorsed. However, because the practical

problems in implementing previous recommendations based on

the European Society of HTN (ESH) and the European Society

of Cardiology (ESC) HTN guidelines, it has been decided to use

a modification of this approach.

Once the diagnosis of HTN is established, patients with BP

≥

160/100 mmHg should commence drug therapy and lifestyle

modification. Patients with stage 1 HTN should receive lifestyle

modification for three to six months unless they are stratified

as high risk by the following criteria: three or more major risk

factors, diabetes, target-organ damage or complications of HTN

(Table 4).

Routine baseline investigations

Table 5 lists recommended routine basic investigations. The

tests are performed at baseline and annually unless abnormal.

Abnormal results must be repeated as clinically indicated.

Table 2. Recommendations for blood pressure measurement

Allow patient to sit for 3–5 minutes before commencing measurement

The SBP should be first estimated by palpation to avoid missing the

auscultatory gap

Take two readings 1–2 minutes apart. If consecutive readings differ by

5 mm, take additional readings

At initial consultation measure BP in both arms, and if discrepant use

the higher arm for future estimations

The patient should be seated, back supported, arm bared and arm

supported at heart level

Patients should not have smoked, ingested caffeine-containing bever-

ages or food in previous 30 min

An appropriate size cuff should be used: a standard cuff (12 cm) for

a normal arm and a larger cuff (15 cm) for an arm with a mid-upper

circumference

33 cm (the bladder within the cuff should encircle

80% of the arm)

Measure BP after 1 and 3 minutes of standing at first consultation in

the elderly, diabetics and in patients where orthostatic hypotension is

common

When adopting the auscultatory measurement use Korotkoff 1 and V

(disappearance) to identify SBP and DBP respectively

Take repeated measurements in patients with atrial fibrillation and

other arthythmias to improve accuracy

Table 3. Definitions of hypertension by different

methods of BP measurement

Office

Auto-

mated

office Self

Ambulatory

Predicts outcome

+ ++ ++

+++

Initial diagnosis

Yes

Cut-off BP (mmHg)

140/90 Mean

135/85

135/85 Mean day 135/85

Mean night 120/70

Evaluation of treatment Yes

Yes

Yes Limited, but valuable

Assess diurnal variation No No No

Yes