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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 30, No 2, March/April 2019
AFRICA
125
equipment (including blood pressure devices) available in their
new place of work. Adherence to the institutional protocol is
strongly recommended.
Taking only a single blood pressure reading without repeating
the measurement may lead to error. This is because a spurious
reading and/or anxiety may falsely elevate the first blood
pressure measurement.
6
Recent organisational guidelines suggest
that the first reading should be discarded and the average
of an additional two readings be regarded as the patient’s
blood pressure.
71
Additionally, the
FIGO Textbook of Pregnancy
Hypertension: An Evidence-based Guide toMonitoring, Prevention
and Management
6
recommends that when an auscultatory device
is used, the first reading should be discarded and the average of
the second and third measurements should represent the blood
pressure value. With an automated device, the same literature
recommends that a total of two measurements should be
performed and the average taken as the blood pressure value.
6
The important message is that at least two to three blood
pressure measurements should be taken to improve accuracy.
Since in many health facilities, the most popular equipment
used for blood pressure measurement is either an automated or
auscultatory device, an evidence-based technique of auscultatory
and automated blood pressure measurement is presented in Table
1. The information therein has been reduced in size, making it
handy to be utilised in a health facility for easy referencing.
Further care of patients with abnormal blood
pressure
An abnormal blood pressure should alert clinicians to take
further actions directed by institutional and national guidelines
or other guidelines endorsed by the health facility. Examples of
such guidelines include the Maternity Care Guidelines in South
Africa
72
and the international practice recommendations of the
ISSHP.
1
Treatment of severe high blood pressure: a systolic blood
pressure
≥
160 mmHg and/or a diastolic blood pressure
≥
110
mmHg in pregnancy is regarded as severe hypertension and
constitutes an emergency.
1,77
Persistence of severe hypertension
after 15 minutes requires administration of a first-line rapid-
acting antihypertensive drug (such as immediate-release oral
nifedipine, intravenous labetalol or dihydralazine) to reduce the
blood pressure.
1,62,72,77
Administration of magnesium sulphate
to prevent eclampsia may also be required.
112
An expeditious,
controlled reduction of blood pressure, commenced within 30
to 60 minutes of confirmed diagnosis, is required to prevent
maternal stroke.
77
The immediate target blood pressure in
such an emergency is 140–150/90–100 mmHg, which prevents
prolonged exposure to severe systolic hypertension that may
result in a loss of autoregulation of cerebral vasculature.
77
In
fact, it has been shown through 28 case series of maternal stroke
associated with pre-eclampsia with severe features (or eclampsia)
that the presence of severe systolic hypertension was commoner
than severe diastolic hypertension just prior to occurrence of the
stroke.
20
Assessment of myocardial performance: importantly, there
may also be a need to assess myocardial performance, given that
blood pressure is a function of cardiac output. The assessment of
myocardial performance includes global and regional measures.
The traditional measures include assessment of left ventricular
ejection fraction and left ventricular mass. However, with a
Doppler echocardiography, the global haemodynamic status of
the ventricular function may be obtained and the indices include:
myocardial performance index (MPI) or Tei index, rate of
increase in pressures inside the left ventricle during systole (dP/
dT), stroke volume, and cardiac output.
113
On the other hand,
the indices for the assessment of regional ventricular systolic
function include: (1) those that assess the wall motion such as
wall-motion score index, qualitative and/or semi-quantitative
assessment of regional wall; and (2) those that assess systolic
cardiac mechanics and deformation such as tissue Doppler
imaging (TDI) techniques and/or speckle-tracking imaging
(STI).
113
It is pertinent that these specialised investigations are
performed by a trained medical technologist and interpreted by
an experienced clinician or cardiologist.
Challenges associated with blood pressure
measurement in pregnancy and HDP
The challenges associated with blood pressure measurement
during pregnancy may be divided into manufacturer-, patient-,
health system- and health worker-related factors.
Manufacturer-related factors: some blood pressure-measuring
devices on the market do not give an accurate reading in
pregnancy.
114
It is necessary for the manufacturers of blood
pressure-measuring devices to test their products in pregnancy
conditions prior to marketing. Validation of the accuracy of
these devices by independent experts is also recommended. The
product/manufacturer’s insert or instructions should specify the
limitations of the device indicating if accuracy in pregnancy has
been established.
Patient-related factors: cultural beliefs interfere with patients’
acceptance of appropriate techniques of blood pressure
measurement.
115
Ongoing public health education will assist in
solving this challenge.
Health system-related factors: these include lack of access
to healthcare services, unavailability of approved devices and
cuff,
116
and lack of training of new employees on how to use the
devices in their current workplace. To address these issues, policy
development and implementation are required. Such policies
include those related to procurement of appropriate hospital
equipment, the maintenance of these gadgets, organisation of
induction courses for new employees and periodic hands-on
patient-simulated continuous medical education for medical
staff. Support for research and innovative ideas will also facilitate
the development of ‘error-free’ devices.
Healthcare professional-related factors (inappropriate
technique): these include inadequate patient preparation such
as counselling, inappropriate patient position, and failure to
consider co-morbidities such as prosthetic heart valves and
arteriosclerosis.
117
Other notable operational errors (including
last-digit error and missing of auscultatory gaps), incorrect
patient posture (such as crossed leg during measurement), and
an insufficient number of measurements before concluding
on the blood pressure value. The frequency of use of a single
measurement has been estimated to be 96%, and this may
increase the mean blood pressure by 8 mmHg. Conversation
during measurement occurs in 41% of cases and results in up
to 20% increase in both systolic and diastolic blood pressure.
Crossed leg occurs in 15% of measurements and increases the