|
Systolic BP is controlled by the
stroke volume of the heart and the stiffness of the
arterial vessels. Diastolic BP is controlled by the
peripheral resistance.
BP varies from moments to moments with respiration,
emotion, exercise, meals, alcohol, tobacco, bladder
distension, temperature and pain. It is also
influenced by circadian rhythm, age and race. BP may
be modified by obesity.
Precautions while taking BP:
-
Explain the procedure to the
patient to allay anxiety.
-
Avoid exertion, meals or smoking
for 30 minutes before BP is measured. The
patient must be allowed to rest for 5 minutes
before BP is measured.
-
The room should be warm and
quiet.
-
High BP may be erroneously
recorded in an obese person because the
inflatable rubber bladder may be too short for
the obese arm. When the bladder does not
completely encircle the arm the centre of the
bladder must be placed directly over the
brachial artery.
-
The arm should be supported to
the heart level. In sitting and standing
positions the arm must be horizontal with fourth
intercostal space at the sternum.
-
If the arm is unsupported ,the
patient will perform isometric exercise which
may elevate the diastolic BP by 10%.
-
The BP may be higher in right
arm y 2-10 mmHg. Most pressure in practice are
measured on the right arm. However if the BP is
higher by 10mm Hg in one arm further
measurements should be made in that arm.
-
Conditions diagnosed by measuring
BP:
-
Hypertension
-
Hypotension
-
Pulsus paradoxus
-
Pulsus alternans
-
Coarctation of aorta
-
Aortic incompetence
Unequal BP in two arms:
In normal individuals ,BP may vary due to recording
at different times in the two arms. Also it is due
to unilateral occlusive disease of the arteries.
|
