blood pressure
TRANSCRIPT
BLOOD PRESSURE
DR NILESH KATE
MBBS,MD.
OBJECTIVESAt 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.
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.
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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 formationOf the lymph.
Normal Values
Normal Adult range Can fluctuate within a
wide range and still be normal
Systolic/diastolic 100/60 - 140/80
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 loadon 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.
Pulse Pressure (P.P)
Denotes the difference between systolic and diastolic pressure. PP= SBP - DBP = 40 mm Hg
MEAN ARTERIAL PRESSUREMean arterial .BP = DBP + 1/3 Pulse Pressure
normal = 95 mm Hg.
•Not the arithmetical mean but geometricalmean.
•It is because the period of the systole is only 0.3 sec when compared to 0.5 sec of the diastole.
ARTERIAL BLOOD PRESSURE
PHYSIOLOGICAL VARIATION IN BLOOD PRESSURE
A) AgeB) BuildC) ClimateD) Diurnal VariationE) ExerciseF) Fever
G) GestationH) high AltitudeI) Infusion/ IntakeJ) PainK) PostureL) SleepM) sex
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RECORDING OF B.P
Direct method
Indirect method
METHODS
Indirect Methods
1. Palpatory method 2. Auscultatory
method
PRINCIPLE INVOLVED IN RECORDING BLOOD PRESSURE
Slide 11.37
Measurement Device
Aneroid sphygmomanometer Simple mercury
sphygmomanometer
Automated bp device
3
RECOMMENDED BLOOD PRESSURERECOMMENDED BLOOD PRESSUREMEASUREMENT 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
brachia l 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
brachia l artery.brachia l artery.
1.• The patient should
be relaxed and thearm must besupported.
• Ensure no tightclothing constrictsthe arm.
1.1.•• The patient shouldThe patient should
be relaxed and thebe relaxed and thearm must bearm must besupported.supported.
•• Ensure no tightEnsure no tightclothing constrictsclothing constrictsthe arm.the arm.
3.• The column of
mercury must bevertical .
• Infla te to occlude thepulse. Deflate at 2 to3 mm/s. Measuresystolic (first sound)and diastolic(disappearance) tonearest 2 mm Hg.
3.3.•• The column ofThe column of
mercury must bemercury must bevertical .vertical .
•• Infla te to occlude theInfla te to occlude thepulse. Deflate at 2 topulse. Deflate at 2 to3 mm/s. Measure3 mm/s. Measuresystolic (first sound)systolic (first sound)and diastolicand diastolic(disappearance) to(disappearance) tonearest 2 mm Hg.nearest 2 mm Hg.
StethoscopeStethoscope
MercuryMercurymachinemachine
Tapping sound 1SBP
110 mm Hg
Banging sound 3
Muffing sound 4
DBP-
95 mm Hg
85 mm Hg
Recording of arterial BP by auscultatory method
Korotkovsounds
120 mm Hg
Murmurish 2
80 mm Hg No sound 5
AUSCULTATORY METHOD This method was introduced by a Russian physicianKorotkov
FACTORS MAINTAININGBLOOD PRESSURE
1. Cardiac output (CO= SV X PR) 2. Circulating blood volume
(This mainly affects systolic B.P)3. Elasticity of the vessel wall4. Viscosity of blood
Viscosity is affected by1. Cell count 2. Plasma proteins 3. Chemical composition like CO2, O2 content,PH.4. Temperature 5. Drugs like general anaesthetics. All these factors influence peripheral resistance through viscosity
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Peripheral Vascular Resistance
It is defined as the resistance offered to the flow of bloodby the blood vessels.
It is contributed by: The Smooth muscles of the arterioles in particular.
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 youngadult 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/cm2
Pressure dyne/cm2 PR =
Flow cc/sec
= dyne/sec/cm2
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 vascularcompression
Radius of BV DP
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CO TPRHR SV
ANSHormonesBrain
EDV
Venous Return
Kidney
AngiotensinAldosteroneADH
Respiratory pumpSkeletal muscle pump
ANSHormonesViscosityBlood vessel lengthBlood vessel diameterLocal 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
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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
ReninAngiotensin Angiotensin I ACEAngiotensin I Angiotensin II
ACE - Angiotensin Converting Enzyme ( Present in the lungs)
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ACTION OF ANGIOTENSIN - II
1. Vasoconstriction2. 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
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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 REGULATIONS1) Catecholamines2) Mineralocorticocoid3) Glucocorticoid4) Thyroxine5) ADH6) Atrial Natriuretic Factor7) Nitric Oxide8) Histamine9) Angiotensin10) Serotonin
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
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BP is called Hypertension (Above 140/90 mm of Hg )
Primary(Essential 90%)
Secondary(10%)
Diseases Attributable to Hypertension
Hypertension
Heart failureStroke
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.
AllVascular
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HypertensionPredisposing factors: Obesity Hereditary Alchoholism Stress Smoking Sedentary life
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Secondary HypertensionCauses: 1.Renal-Acute & Chronic
Glomerulonephritis,Nephrotic syndrome 2.Endocrine-
Cushings,Conns,Thyrotoxicosis, Pheochromacytoma 3.Vascular-Atherosclerosis Arteriosclerosis
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Treatment of HypertensionModification 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 Ca2+ channels.
ACE inhibitors: Inhibit conversion to angiotensin II.
Angiotension II-receptor antagonists: Block receptors.
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
Hypotension
Defined in adults as a systolic pressure below 100mm Hg
Rarely treated in this country
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BP is called Hypotension (Below 90/60 mm of Hg)
1. Hemorrhage2. Dehydration3. Vomiting4. Diarrhea5. Excessive sweating6.Adissons disease7.Hypothyroidism
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Treatment of Hypotension
Treat the causeBlood transfusionI.V. FluidsVasoconstrictors
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RECAPAt the end of this class, you should able to recall.1. Definition of Blood Pressure2. Its variations.3. Measurement - Korotkov sound4. Factors contributing to B.P5. Peripheral resistance 6. Regulation of BP7. Immediate regulation8. Short term regulation9. Long term regulation.10. Applied - Hypertension - Hypotension
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Success is one percent inspiration And ninety nine percent perspiration
Thank You