Blood pressure

BLOOD PRESSURE

1. BLOOD PRESSURE
DR NILESH KATE
MBBS,MD.

2. OBJECTIVES
At the end of this class, you should able to recollect.
Definition of Blood Pressure Its variations.
 Measurement - Korotkoff sound
 Factors contributing to B.P
 Peripheral resistance
 Regulation of BP
 Immediate regulation
 Short term regulation
 Long term regulation.
 Applied - Hypertension - Hypotension
 Physiology of treatment.

3. ARTERIAL BLOOD PRESSURE
Definition : Arterial blood pressure can be
defined as the lateral pressure exerted
by the moving column of blood on the
walls of the arteries.

4. Tuesday, February 16, 2016

5. SIGNIFICANCE
1.To ensure the blood flow
To various organs.
2. Plays an important role
in exchange of nutrients
and gases across the
capillaries.
3. Required to form urine.
4. Required for the formation
Of the lymph.

6. Normal Values
 Normal Adult range
 Can fluctuate within a
wide range and still
be normal
 Systolic/diastolic
 100/60 - 140/80

7. Systolic B.P (S.B.P)
Defined as the maximum
B.P in the arteries
Attainable during systole.
Normal 120 + 20 mm Hg.
This is mainly contributed by
1. Force of heart beat
2. Normal blood volume
3. Cardiac output.
Normal range
90-140 mm Hg.

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DIASTOLIC B.P (D.B.P)
Def--- as the minimum
pressure that is obtained at the
end of the ventricular diastole.
Normal range 60 -90 mm Hg.
1. It represents a constant load
on the arterial walls with
little or no fluctuation at all.
2. It is an index to the
peripheral resistance and
decides the filling of the
Coronary system.

9. Pulse Pressure (P.P)
Denotes the difference
between
systolic and diastolic
pressure.
PP= SBP - DBP = 40
mm Hg

10. MEAN ARTERIAL PRESSURE
Mean arterial .BP = DBP +
1/3 Pulse Pressure
normal = 95 mm Hg.
•Not the arithmetical mean but geometrical
mean.
•It is because the period of the systole is only
0.3 sec when compared to 0.5 sec of the
diastole.

11. ARTERIAL BLOOD PRESSURE

12. PHYSIOLOGICAL VARIATION IN BLOOD
PRESSURE
A) Age
B) Build
C) Climate
D) Diurnal Variation
E) Exercise
F) Fever
G) Gestation
H) high Altitude
I) Infusion/ Intake
J) Pain
K) Posture
L) Sleep
M) sex

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RECORDING OF B.P
Direct method
Indirect method
METHODS
Indirect Methods
1. Palpatory method
2. Auscultatory
method

14. PRINCIPLE INVOLVED IN RECORDING BLOOD
PRESSURE
Slide
11.37

15. Measurement Device
Aneroid
sphygmomanometer
Simple mercury
sphygmomanometer
Automated bp device

16. 3
RECOMMENDED BLOOD PRESSURERECOMMENDED BLOOD PRESSURE
MEASUREMENT TECHNIQUEMEASUREMENT TECHNIQUE
2.
•The cuff must be level with heart.
•If arm circumference exceeds 33 cm,
a large cuff must be used.
•Place stethoscope diaphragm over
brachial artery.
2.2.
••The cuff must be level with heart.The cuff must be level with heart.
••If arm circumference exceeds 33 cm,If arm circumference exceeds 33 cm,
a large cuff must be used.a large cuff must be used.
••Place stethoscope diaphragm overPlace stethoscope diaphragm over
brachial artery.brachial artery.
1.
•The patient should
be relaxed and the
arm must be
supported.
•Ensure no tight
clothing constricts
the arm.
1.1.
••The patient shouldThe patient should
be relaxed and thebe relaxed and the
arm must bearm must be
supported.supported.
••Ensure no tightEnsure no tight
clothing constrictsclothing constricts
the arm.the arm.
3.
•The column of
mercury must be
vertical.
•Inflate to occlude the
pulse. Deflate at 2 to
3 mm/s. Measure
systolic (first sound)
and diastolic
(disappearance) to
nearest 2 mm Hg.
3.3.
••The column ofThe column of
mercury must bemercury must be
vertical.vertical.
••Inflate to occlude theInflate to occlude the
pulse. Deflate at 2 topulse. Deflate at 2 to
3 mm/s. Measure3 mm/s. Measure
systolic (first sound)systolic (first sound)
and diastolicand diastolic
(disappearance) to(disappearance) to
nearest 2 mm Hg.nearest 2 mm Hg.
StethoscopeStethoscope
MercuryMercury
machinemachine

17. Tapping sound 1
SBP
110 mm Hg
Banging sound 3
Muffing sound 4
DBP-
95 mm Hg
85 mm Hg
Recording of
arterial BP by
auscultatory
method
Korotkov
sounds
120 mm Hg
Murmurish 2
80 mm Hg
No sound 5
AUSCULTATORY METHOD
This method was introduced by a Russian physician
Korotkov

18. FACTORS MAINTAINING
BLOOD PRESSURE
1.Cardiac output (CO= SV X PR)
2.Circulating blood volume
(This mainly affects systolic B.P)
3.Elasticity of the vessel wall
4.Viscosity of blood

19. Viscosity is affected by
1.Cell count
2.Plasma proteins
3.Chemical composition like
CO
2,
O
2
content,PH.
4. Temperature
5.Drugs like general anaesthetics.

All these factors influence
peripheral resistance through viscosity

20. 02/16/1602/16/16
Peripheral Vascular Resistance
It is defined as the resistance
offered to the flow of blood
by the blood vessels.
It is contributed by:
The Smooth muscles of the
arterioles in particular.

21. FACTORS AFFECTING BLOOD PRESSURE
Disease
Age
Heredity
Blood Volume
Weight
Diet
Hormones
Salt
Caffeine
Environmental
factors
Psychological factors
Stress/Anxiety
Gravity
Drugs
Alcohol
Time of day

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BP = Cardiac output X PR
Peripheral resistance(PR) in a normal healthy young
adult is 20mm Hg/lit/mt.
Peripheral vascular resistance: depends upon
A) Velocity of blood
B) Viscosity of blood
C) Elasticity of the
vessels wall
D) Lumen of the vessels
E) Length of the vessels
F) Extra vascular
compression
BLOOD PRESSURE
100 = 5X20

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Peripheral Resistance
Obsolute units: Dyne/sec/cm
2
Pressure dyne/cm
2

PR =
Flow cc/sec
= dyne/sec/cm
2
P.R.U unit: (Relative unit) When there is a
difference of 1 mm Hg and a flow of 1ml/sec
then it is called one PRU unit.

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Ernest H. Starling in the dog lab (1915)

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FACTORS CONTRIBUTING
TO BLOOD PRESSURE
1 Cardiac output-VR,HR,FOC—S.P
2. PERIPHERAL RESISTANCE

Elasticity Viscosity

Velocity
Length of BV
Extra vascular
compression
Radius of BV
DP

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CO TPR
HR SV
ANS
Hormones
Brain
EDV
Venous Return
Kidney
Angiotensin
Aldosterone
ADH
Respiratory pump
Skeletal muscle pump
ANS
Hormones
Viscosity
Blood vessel length
Blood vessel diameter
Local factors
MAP

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REGULATION OF ARTERIAL
BLOOD PRESSURE
Immediate mechanism
Short term mechanism
Long term mechanism

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ImmediateImmediate Regulatory Mechanisms:
Neural mechanisms
1.Baroreceptor
reflexes
2. Chemo receptor
reflexes

3. Cerebral ischaemic
response

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BARORECEPTOR REFLEX

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BARO RECEPTOR REFLEXES (MAREY’S REFLEXES)
BP­
¯
Stimulation of baroreceptors
(carotid sinus and aortic arch)
¯
Tractus solitarius stimulation
Inhibition of VMC Stimulation of CIC
(nucleus ambiguous)
SNS Vagus
¯ Symp tone Vagal tone ­
Blood Vessels Heart Rate Decreased

- Vasodilatation
- Venodilatation Bradycardia

BP

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Net effect
¯ Peripheral resistance
¯ Myocardial contractility
¯ Heart rate (Bradycardia)
¯ Fall in BP

BARORECEPTOR REFLEX

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¯ BP <60 mm Hg
Hypoxia
Chemoreceptors

NTS Respiratory centre CIC

VMC stimulation N ambiguus

Vagus

SNS action­ ¯ Vagaltone
Net effect ­ Pulmonary ventilation, ­ BP, ­ Heart rate
Chemo receptor reflexes

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¯ BP < 40 mm Hg (or)
­ Intracranial pressure
Cerebra ischaemia

Cerebral hypoxia

Direct effect on
VMC
SNS action ­
Vasoconstriction

Cerebral Ischaemic Response
­ BP with reflex
bradycardia
Cushing’s Reflex

35. 02/16/1602/16/16
REGULATION OF ARTERIAL
BLOOD PRESSURE
Short term regulatory mechanisms:
These are again
divided into
a) acute regulatory
mechanisms
b) delayed regulatory
mechanisms.

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Delayed or Intermediate Mechanism

Capillary fluid shift phenomenonCapillary fluid shift phenomenon:
Whenever there is an increase in blood pressure
more fluid is filtered through the capillary wall into
the interstitial space.
Blood volume decreases
and so BP itself decreases.
Reverse changes take
place when BP falls.

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Delayed or Intermediate Mechanism
Renin –Angiotensin System
Whenever there is a fall in B.P, there is a
decrease in the blood flow to the kidney.
This results is ischaemic kidney.
Renin is released from J.G. cells
Renin
Angiotensin Angiotensin I
ACE
Angiotensin I Angiotensin II
ACE - Angiotensin Converting Enzyme
( Present in the lungs)

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ACTION OF ANGIOTENSIN - II
1.Vasoconstriction
2. Aldosterone secretion
3. Stimulation of the
thirst centre
4. Increased absorption
of Na
+
from PCT by
direct effect. As a result

. B.V ­, C.O ­. BP ­

39. Tuesday, February 16, 2016

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Stress Relaxation Phenomenon:
­BP

Blood vessels are stretched
Stress relaxation
Increased capacity
Decreased effective
blood volume
BP decreased
relaxation
¯BP

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Long term Regulatory Mechanisms:
All the mechanisms
that tend to alter the
blood volume
participate in
Long term regulatory
mechanisms

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Renal –body fluid system:
­ECF or Blood volume
- ­ BP
B.P is brought back to
the normal level
¯ECF or Blood volume
- ¯BP
B.P is slowly raised to
the normal level.
­ GFR ­ urine output ¯ GFR BP ¯ urine output

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HORMONAL REGULATIONS
1) Catecholamines
2) Mineralocorticocoid
3) Glucocorticoid
4) Thyroxine
5) ADH
6) Atrial Natriuretic Factor
7) Nitric Oxide
8) Histamine
9) Angiotensin
10) Serotonin

44. Hypertension
Defined as an elevation of systolic
blood pressure
Persistent hypertension very common
30% of people over 50 are
hypertensive
Never diagnosed on one reading
Indication of cardiovascular disease
Trauma
Side effect of medication

45. 02/16/1602/16/16
­ BP is called Hypertension
(Above 140/90 mm of Hg )
Primary
(Essential 90%)
Secondary
(10%)

46. Diseases Attributable to
Hypertension
Hypertension
Heart failure
Stroke
Coronary heart disease
Myocardial infarction
Left ventricular
hypertrophy
Aortic aneurysm
Retinopathy
Peripheral vascular disease
Hypertensive
encephalopathy
Chronic kidney failure
Cerebral hemorrhage
Adapted from: Arch Intern Med 1996; 156:1926-1935.
All
Vascular

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Hypertension
Predisposing factors:
Obesity
Hereditary
Alchoholism
Stress
Smoking
Sedentary life

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Secondary Hypertension
Causes:
1.Renal-Acute & Chronic
Glomerulonephritis,Nephrotic syndrome
2.Endocrine-
Cushings,Conns,Thyrotoxicosis,
Pheochromacytoma
3.Vascular-Atherosclerosis
Arteriosclerosis

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Treatment of Hypertension
Modification of lifestyle:
Cessation of smoking.
Moderation in alcohol intake.
Weight reduction.
Programmed exercise.
Reduction in Na
+
intake.
Diet high in K
+
.
Relaxation technique – Yoga, TM

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Treatment of Hypertension
Medications:
Diuretics:
Increase urine volume.
Beta-blockers:
Decrease HR.
Calcium antagonists:
Block Ca
2+
channels.
ACE inhibitors:
Inhibit conversion to angiotensin II.
Angiotension II-receptor antagonists:
Block receptors.

51. Prevention
Reduce the risk of developing High Blood
Pressure by making lifestyle changes…..
Eat a healthy , well balanced diet
Reduce salt and fat intake
Exercise regularly
Stop smoking
Reduce alcohol and caffeine consumption to
recommended levels
Reduce weight

52. Hypotension
 Defined in adults as a
systolic pressure below
100mm Hg
Rarely treated in this
country

53. 02/16/1602/16/16
¯ BP is called Hypotension
(Below 90/60 mm of Hg)
1. Hemorrhage
2. Dehydration
3. Vomiting
4. Diarrhea
5. Excessive
sweating
6.Adissons disease
7.Hypothyroidism

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Treatment of Hypotension
Treat the cause
Blood transfusion
I.V. Fluids
Vasoconstrictors

56. 02/16/1602/16/16
RECAP
At the end of this class, you should able to
recall.
1. Definition of Blood Pressure
2. Its variations.
3. Measurement - Korotkov sound
4. Factors contributing to B.P
5. Peripheral resistance
6. Regulation of BP
7. Immediate regulation
8. Short term regulation
9. Long term regulation.
10. Applied - Hypertension - Hypotension

57. 02/16/1602/16/16
Success is one percent
inspiration
And
ninety nine percent
perspiration

58. Thank You