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Hypertension

Hypertension. Definition: the force exerted by the blood against the walls of the bleed vessels Adequate to maintain tissue perfusion during activity and rest Arterial blood pressure: primary function of cardiac output and systemic vascular resistance. Hypertension.

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Hypertension

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  1. Hypertension • Definition: the force exerted by the blood against the walls of the bleed vessels • Adequate to maintain tissue perfusion during activity and rest • Arterial blood pressure: primary function of cardiac output and systemic vascular resistance

  2. Hypertension Arterial BP = Cardiac Output (CO) x Systemic vascular resistance (SVR) Cardiac Output = stroke volume x beats per min Systemic vascular resistance = force opposing the movement of blood within the blood vessels What is the effect on BP if SVR increased and CO remains constant?

  3. HypertensionMechanisms that Regulate BP • Sympathetic Nervous System • Vascular Endothelium • Renal System • Endocrine System

  4. HypertensionMechanisms that Regulate BP • Sympathetic Nervous System (SNS) – norepinephrine released from sympathetic nerve endings - to receptors alpha1, alpha2, beta 1 & beta2 • Reacts within seconds • Increases Heart Rate - chronotropic • Increased cardiac contractility - inotropic • Produces widespread vasoconstriction in peripheral arterioles • Promotes release of renin from the kidney

  5. HypertensionSNS Receptors Influencing B/P

  6. HypertensionMechanisms that Regulate BP • Sympathetic Nervous System (SNS)– • Sympathetic Vasomotor Center – located in the medulla – interacts with many areas of the brain to maintain BP within normal range under various conditions • Exercise – changes to meet oxygen demand • Postural Changes – peripheral vasoconstriction

  7. HypertensionMechanisms that Regulate BP • Sympathetic Nervous System (SNS) – • Baroreceptors: specialized nerve cells the carotid arteries and the aortic arch • Sensitive to BP changes: • Increase: Inhibits SNS – peripheral vessel dilation. Decreased heart rate, and decreased contractility of the heart + increased parasympathetic activity (vagus nerve) decreased heart rate • Decrease: Activates SNS – peripheral vessel constriction, increased heart rate, and increased contractility of the heart

  8. HypertensionMechanisms that Regulate BP • Vascular Endothelium • Single cell layer that lines the blood vessels • Produce vasoactive substances: • EDRF Endothelium-derive relaxing factor – • Helps maintain low arterial tone at rest • Inhibits growth of the smooth muscle layer • Inhibits platelet aggregation • Vasodilation – prostacyclin • Endothelin (ET) potent vasoconstrictor Endothelial dysfunction may contribute to atherosclerosis & primary hypertension

  9. HypertensionMechanisms that Regulate BP • Renal System • Control Na+ excretion & extracellular fluid volume • Renal - Renin-angiotensin-aldosterone • Renin converts angiotensinogen to angiotensin I • Angiotensin-converting enzyme (ACE) converts I into angiotsensin II • Immediate: Vasoconstrictor – increased systemic vascular resistance • Prolonged: Stimulates the adrenal cortex to secret Aldosterone – Na+ and Water retention • Renal Medulla - Prostaglandins - vasodilator effect

  10. HypertensionRenin-Angiotensin

  11. HypertensionRenin-Angiotensin System

  12. HypertensionMechanisms that Regulate BP • Endocrine System • Stimulates the SNS with • Epinephrine – increases HR and contractility • Activates B2-adrenergic receptors in peripheral arterioles of skeletal muscle = vasodilation • Activates A1-adrenergic receptors in peripheral arterioles of skin and kidneys = vasoconstiction • Adrenal Cortex – Aldosterone – stimulates kidneys to retain Na+ • Increased Na+ stimulates posterior pituitary – ADH – reabsorbs ECF/water

  13. HypertensionAldosterone Mechanism • Increased Aldosterone = • Increases sodium reabsorption = • Increases water reabsorption = • Increases blood volume = • Increases cardiac output

  14. HypertensionMechanisms that Regulate BP • Regulatory mechanisms in the health person function in response to the demands on the body • When Hypertension develops, one or more of these mechanisms are defective • Sympathetic Nervous System • Vascular Endothelium • Renal System • Endocrine System

  15. Secondary HypertensionPathophysiology • Specific cause of hypertension can be identified • 5+% of adult hypertension • Causes: • Coarctation or congenital narrowing of the aorta • Renal disease – renal artery disease / parenchymal • Endocrine disorders: Pheochromocytoma, Cushing Syndrome, Hyperaldosteronism • Neurology disorders – brain tumors / head injury • Sleep apnea • Medications – sympathetic stimulants • Pregnancy-induced hypertension

  16. HypertensionPathophysiology • Primary (Essential) Hypertension: • Elevated BP without an identified cause • Accounts for 95% of all cases of hypertension • Cause – unknown • Contributing Factors: Increased SNS activity, overproduction of Na+ retaining hormones & vasoconstrictors, increased Na+ intake • Risk Factors: Modifiable

  17. Primary HypertensionPathophysiology • Heredity – interaction of genetic, environmental, and demographic factors • Water & Sodium Retention – 20% of pts with high Na+ diet develop HTN • Altered Renin-Angiotensin Mechanism – found in 20% of patients • Stress & Increased SNS Activity • Insulin Resistance & Hyperinsulinemia • Endothelial Cell Dysfunction

  18. HypertensionClinical Manifestation Dx is made after multiple readings over several weeks NIH/Joint Committee Definition: Category Systolic Diastolic Optimal <110 and < 80 Normal <120 and <85 High Normal 130-139 or 85-89 Stage 1140-159 or 90-99 Stage 2 160-179 or 100-109 Stage 3 =>180 or => 110

  19. Primary HypertensionRisk Factors • Age • Alcohol • Cigarette Smoking • Diabetes Mellitus • Elevated serum lipids • Excess Na+ in diet • Gender • Family History • Obesity • Ethnicity • Sedentary Lifestyle • Socioeconomic • Stress

  20. Primary HypertensionClinical Manifestations • Target Organ Complications: • Myocardium – angina / left ventricular hypertrophy • Brain – TIA / CVA • Peripheral vascular – Peripheral pulse change • Kidney – renal failure Creatinine / Proteinuria • Eyes – Hemorrhages with or without papilledema

  21. Primary HypertensionClinical Manifestations • “Silent Killer” – asymptomatic and insidious • Severe HTN – fatigue, reduced activity tolerance, dyspnea, dizziness, palpitations, angina

  22. HypertensionMedical Diagnosis • History and Physical Examination • Renal Function • Serum Creatinine & Urine Creatinine Clearance • Electrolytes – especially K+ • Blood Glucose • Serum Lipids/EKG • Ambulatory BP Monitoring

  23. Primary HypertensionMedical Management • Risk Stratification • Level of BP • Presence of Target Organ Disease • Other Risk Factors

  24. HypertensionMedical ManagementRisk Stratification

  25. Primary HypertensionMedical Management • Lifestyle modification • Nutritional therapy • Alcohol consumption • Physical activity • Tobacco avoidance • Stress management • Drug Therapy

  26. HypertensionNutrition

  27. HypertensionRisk Factor Modification

  28. Primary HypertensionMedical ManagementStepped Approach Lifestyle modification Not at Goal BP Drug Therapy Not at Goal BP Substitute med / add a 2nd med/ increase dose Not at Goal BP Continue adding / changing meds until control

  29. Primary HypertensionMedical Management – Drug Therapy • Diuretics • Thiazide • Loop • K+ Sparing • Adrenergic Blockers/ Inhibitors • B-Adrenergic Blockers • Central Acting Adrenergic Antagonists • Peripheral Acting Adrenergic Antagonists • A-Adrenergic Blockers • Vasodilators • Angiotensin Inhibitors • Calcium Channel Blockers

  30. HypertensionMedication - Diuretics

  31. HypertensionMedication – Beta-blocking Agents

  32. HypertensionMedication Calcium Channel Blockers

  33. Hypertension MedicationAlpha Agonists & Vasodilators

  34. HypertensionAntihypertensive Drug Therapy

  35. Primary HypertensionLack of Responsiveness to Therapy • Nonadherence to Therapy • Drug-Related Causes • Associated conditions • Secondary Hypertension • Volume overload

  36. Primary HypertensionHypertensive Crisis • Definition: Severe & abrupt elevation of BP with diastolic > 120-130mm Hg. • Causes: • Nonadherence, renovascular changes, pre- eclampsia, eclampsia, Pheochromocytoma, Rebound from abruptly stopping beta blockers, head injury, necrotizing vasculitis, acute aortic dissection • Hypertensive Encephalopathy: • headache, N/V, confusion, obtunded, stuporous, seizures, blurred vision, transient blindness

  37. Primary HypertensionNursing Diagnoses Assess: Cardiovascular status; adherence to therapy; family interaction; risk factor modification? Nsg Action: Supportive & reality-based; Administer meds; referrals; diagnostic preps; ask questions; supportive care during hospitalization for acute crisis Pt/Family Education: Medications; risk factor modification; Community support

  38. HypertensionDynamics of Treatment

  39. Primary HypertensionCase Study

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