Transcript Arterial Blood Pressure (BP)

Arterial Blood
Pressure
Definition.
Factor affecting blood pressure .
Causes .
Classification .
Type of blood pressure apparatuses .
How to measure .
Treatment .
Arterial Blood Pressure (BP)

Is a measure of the force that the circulating blood
exerts against the arterial wall
OR

The pressure force generated by the pumping action of
the heart on the wall of aorta & arterial blood vessels
per unit area.

It tells us how hard the heart is working.

Too high means the heart is working extra hard and this
could be very dangerous!
Blood pressure almost always is measured
in millimeters of mercury (mmHg).
Occasionally pressure is measured in
centimeters of water ( cm H O)
2
1 mmHg = 1.36 cm H2O
Factors affecting BP
Sex M > F …due to hormones/ equal at menopause.
 Age Elderly > children …due to atherosclerosis.
 Emotions  due to secretion of adrenaline &

noradrenaline.
Exercise  due to  venous return.
 Hormones … (e.g. Adrenaline, noradrenaline, thyroid

H).
Gravity  Lower limbs > upper limbs.
 Race Orientals > Westerns … ? dietry factors, or


weather.
Sleep  due to  venous return.
Factors determining BP
Blood Pressure = Cardiac Output X Peripheral Resistance
(BP)
(CO)
Flow
BP depends on:
1. Cardiac output.
2. Peripheral resistance.
3. Blood volume.
(PR)
Diameter of
arterioles
Cardiac Output
Is the volume of blood being pumped by the heart,
in particular by a Left or Right ventricle in the Time
interval of one minute
Cardiac Output (Q) = SV × HR
Peripheral Resistance
The sum of resistance to flow that must be
overcome to push blood through the circulatory
system
Stroke Volume
Is the volume of blood pumped from one ventricle of the
heart with each beat
Causes Of Hypertension
Essential hypertension 95%
 Secondary hypertension 5%

Renal
Endocrine
Pregnancy
Drugs
Coartation of aorta
Others
Blood Pressure
Is the measured
pressure placed on
the blood vessels
while the heart is
contracting.
Is the measured
pressure placed on
the blood vessels
while the heart is
at rest. (not
contracting)
NOTE !!!
Pulse pressure
Systolic BP – Diastolic BP
The most important determinant of pulse pressure is
STROKE VOLUME.
Mean arterial pressure
pressure
Diastolic BP + 1/3 Pulse
Is a term used in medicine to describe an average blood pressure in
an individual
Hypertension
Sustained raised in BP which require medical
interventions.
Classification of blood pressure for adults
Category
Systolic mmHg
Diastolic mmHg
Hypotension
< 90
< 60
Normal
90 – 120
60 – 80
Prehypertension
121 – 139
81 – 89
Stage 1 Hypertension
140 – 159
90 – 99
Stage 2 Hypertension
≥ 160
≥ 100
How is Blood Pressure Taken?
Blood Pressure
Non-Invasive
Palpatory Method
Auscultatory Method
Ultrasonic Method
Oscillometric Method
Invasive
Tonometry
Extravascular Sensor
Intravascular Sensor
Types Of BP Apparatuses

Mercury Type

Aneroid Type

Digital Type
A- Palpatory Method
Feel the radial pulse.
 An occlusive cuff is placed on arm and inflated
above the level at which the pulse become
impalpable.
 Gradually deflate it.
 The level at which the pulse become palpable
again is taken as systolic pressure.

ADVANTAGES
1- The blood pressure can be measured in noisy
environment too
2- Technique does not require much
equipment
DISADVANTAGES
1- Only the systolic pressure can be measured (not DP)
2- The technique does not give accurate results
for infants and hypotensive patients
B- Auscultatory Method

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Apply the cuff one inch above the elbow
Palpate the brachial artery
Place the stethoscope lightly over it
Inflate the cuff above the systolic level determined
by the palpatory method
Lower the pressure in the cuff
The level at which Korotkoff sound are heard is the
Systolic pressure.
The level at which sound disappear is diastolic
pressure.
ADVANTAGES
1- Auscultatory technique is simple and does not require
much equipment
DISADVANTAGES
1- Auscultatory tecnique cannot be used in noisy environment
2- The observations differ from observer to another
3- A mechanical error might be introduced into the system e.g.
mercury leakage, air leakage, obstruction in the cuff etc.
4- The technique does not give accurate results for infants and
hypotensive patients
Korotkoff sound
1.
2.
3.
4.
5.
The first Korotkoff sound is Clear tapping,
repetitive sounds for at least two consecutive beats
is considered the systolic pressure.
The second sounds are the murmurs heard for
most of the area between the systolic and diastolic
pressures.
The third = A loud, crisp tapping sound.
The fourth sound, at pressures within 10 mmHg
above the diastolic blood pressure, were described
as “muffling" and "muting".
The fifth Korotkoff sound is silence as the cuff
pressure drops below the diastolic blood pressure.
The disappearance of sound is considered diastolic
blood pressure .
Common problem in BP measurement
Wrong cuff size
 Excess pressure of stethoscope
 Patient arm at the wrong level
 White coat effect
 Auscultatory Gap (silent gap)

Auscultatory Gap
In some hypertensive patients the
Krotokoff sound disappear for some time
between systolic and diastolic pressure.
 So there is a risk of either recording a
low systolic or high diastolic .
 Avoid it by using palpatory method before
the Auscultatory method.

Treatment

Treatment goal <140/85 mmHg
(130/80 mmHg in diabetic)
Lifestyle changes include :
Stop smoking
Low fat diet
Low salt intake
Exercise
Reduce wt
Drugs:
ACE inhibitor
B-blocker
Ca channel blocker
Diurtics
Postural Hypotension
Drop in systolic BP>20 mmHg OR
diastolic BP>10 mmHg after standing for
3 minutes.
 Causes:
Hypovolemia
Antipsychotics
Addison‘s disease
hypopituitarism

Apply Your Knowledge
Normal Blood Pressure in Adults (18 or older) is ??
 What can cause sounds to be heard down to zero
mmHg??
 A cuff with a bladder too small for the patients arm will
result in ??
 If the cuff is applied too loosely, the pressure
reading will be ??
 How you can avoid incorrectly assessing the systolic
blood pressure due to the auscultatory gap??

Thank you