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Blood pressure

BLOOD PRESSURE

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Blood pressure

  1. 1. BLOOD PRESSURE DR NILESH KATE MBBS,MD.
  2. 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. 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. 4. Tuesday, February 16, 2016
  5. 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. 6. Normal Values  Normal Adult range  Can fluctuate within a wide range and still be normal  Systolic/diastolic  100/60 - 140/80
  7. 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.
  8. 8. 02/16/1602/16/16 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. 9. Pulse Pressure (P.P) Denotes the difference between systolic and diastolic pressure. PP= SBP - DBP = 40 mm Hg
  10. 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. 11. ARTERIAL BLOOD PRESSURE
  12. 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
  13. 13. 02/16/1602/16/16 RECORDING OF B.P Direct method Indirect method METHODS Indirect Methods 1. Palpatory method 2. Auscultatory method
  14. 14. PRINCIPLE INVOLVED IN RECORDING BLOOD PRESSURE Slide
  15. 15. Measurement Device Aneroid sphygmomanometer Simple mercury sphygmomanometer Automated bp device
  16. 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. 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. 18. CTORS MAINTAINING OOD 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. 19. Viscosity is affected by 1. 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
  20. 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. 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
  22. 22. 02/16/1602/16/16 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
  23. 23. 02/16/1602/16/16 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.
  24. 24. 02/16/1602/16/16 Ernest H. Starling in the dog lab (1915)
  25. 25. 02/16/1602/16/16 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
  26. 26. 02/16/1602/16/16 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
  27. 27. 02/16/1602/16/16 REGULATION OF ARTERIAL BLOOD PRESSURE  Immediate mechanism  Short term mechanism  Long term mechanism
  28. 28. 02/16/1602/16/16 mmediatemmediate Regulatory Mechanisms: Neural mechanisms 1. Baroreceptor reflexes 2. Chemo receptor reflexes 3. Cerebral ischaemic response
  29. 29. 02/16/1602/16/16 BARORECEPTOR REFLEX
  30. 30. 02/16/1602/16/16 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
  31. 31. 02/16/1602/16/16 Net effect ↓ Peripheral resistance ↓ Myocardial contractility ↓ Heart rate (Bradycardia) ↓ Fall in BP BARORECEPTOR REFLEX
  32. 32. 02/16/1602/16/16 ↓ 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
  33. 33. 02/16/1602/16/16 ↓ 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
  34. 34. 02/16/1602/16/16 REGULATION OF ARTERIAL BLOOD PRESSURE rm regulatory mechanisms: are again d into regulatory nisms ed regulatory nisms.
  35. 35. 02/16/1602/16/16 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.
  36. 36. 02/16/1602/16/16 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)
  37. 37. 02/16/1602/16/16 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 ↑
  38. 38. Tuesday, February 16, 2016
  39. 39. 02/16/1602/16/16 ess Relaxation Phenomenon: ↑BP Blood vessels are stretched Stress relaxation Increased capacity Decreased effective blood volume BP decreased relaxation ↓BP
  40. 40. 02/16/1602/16/16 rm Regulatory Mechanisms: ll the mechanisms hat tend to alter the blood volume participate in ong term regulatory mechanisms
  41. 41. 02/16/1602/16/16 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
  42. 42. 02/16/1602/16/16 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
  43. 43. 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
  44. 44. 02/16/1602/16/16 ↑ BP is called Hypertension (Above 140/90 mm of Hg ) Primary (Essential 90%) Secondary (10%)
  45. 45. 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
  46. 46. 02/16/1602/16/16 Hypertension Predisposing factors:  Obesity  Hereditary  Alchoholism  Stress  Smoking  Sedentary life
  47. 47. 02/16/1602/16/16 Secondary Hypertension Causes:  1.Renal-Acute & Chronic Glomerulonephritis,Nephrotic syndrome  2.Endocrine- Cushings,Conns,Thyrotoxicosis, Pheochromacytoma  3.Vascular-Atherosclerosis Arteriosclerosis
  48. 48. 02/16/1602/16/16 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
  49. 49. 02/16/1602/16/16 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.
  50. 50. 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
  51. 51. Hypotension  Defined in adults as a systolic pressure below 100mm Hg  Rarely treated in this country
  52. 52. 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
  53. 53. 02/16/1602/16/16 Treatment of Hypotension Treat the cause Blood transfusion I.V. Fluids Vasoconstrictors
  54. 54. 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
  55. 55. 02/16/1602/16/16 Success is one percent inspiration And ninety nine percent perspiration
  56. 56. Thank You

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