Applied Pathophysiology: Altered Perfusion Lecture PDF

Lecture Material is adapted from © 2022 Wolters Kluwer Health, Lippincott Williams & Wilkins Applied Pathophysiology: A Conceptual Approach to the Mechanisms of Disease Chapter 16: Altered Perfusion Module 2: Altered Perfusion Dr. Romeo Batacan Jr. MPAT12001 Medical Pathophysiology Lecture Serie...

Lecture Material is adapted from © 2022 Wolters Kluwer Health, Lippincott Williams & Wilkins Applied Pathophysiology: A Conceptual Approach to the Mechanisms of Disease Chapter 16: Altered Perfusion Module 2: Altered Perfusion Dr. Romeo Batacan Jr. MPAT12001 Medical Pathophysiology Lecture Series Copyright © 2017 Wolters Kluwer Health | Lippincott Williams &Wilkins  Altered Perfusion The inability to adequately oxygenate tissues at the capillary level Factors that could alter perfusion include: Inadequate Inadequate ventilation perfusion  Ventilation-Perfusion Mismatching Problem with the ventilation–perfusion ratio is the most common cause of hypoxemia 1. Inadequate ventilation in well perfused areas of the lungs asthma, pneumonia, pulmonary edema 2. Inadequate perfusion in well‐ventilated areas of the lungs vascular obstructive processes in the lung, such as with a pulmonary embolus McCance KL, Huether S. Pathophysiology. 7th ed. N.S.W, Mosby; 2015  Altered Perfusion The inability to adequately oxygenate tissues at the capillary level Factors that could alter perfusion include: Inadequate Inadequate ventilation perfusion  Impaired Circulation Problems with circulation: inadequate or excess blood flow to tissues or organs Impaired circulatory patency and functioning: 1. injury to the vessels 2. obstructive processes 3. inadequate movement of blood 4. inadequate blood volume  Impaired Circulation: Injury Injury to the vessels: loss of integrity of vessel loss of blood (haemorrhage) through the vessel wall Other causes of hemorrhage aneurysms coagulation disorders degradation of the vessel by neoplasms  Impaired Circulation: Obstruction Obstruction within the vessel: blocks free movement of blood through the circulatory system occluded arteries do not allow oxygenated blood to reach peripheral tissues occluded veins restrict venous return and lead to circulatory congestion Common obstruction: thrombus (blood clot) response to injury: blood clot formation essential during the wound healing process undesired thrombi can also form in either arteries or veins  Impaired Circulation: Obstruction In both arteries and veins, three major factors are responsible for thrombus formation ‐ Virchow’s triad: 1. Vessel wall damage (vasculature) 2. Excessive clotting (blood) 3. Alterations in blood flow (turbulence or sluggish blood movement) (flow) Most common cause of thrombus formation (in https://www.med.unc.edu/wolberglab/images/Virchows %20triad%20revisited.tif/view arteries and contributing to venous thrombosis): Injury to vessel endothelium resulting in formation of atherosclerosis  Impaired Circulation: Vasculature Atherosclerosis: condition of irregularly distributed lipid deposits in the inner lining (intima) of large or medium arteries: inflammatory fibrous cells migrate foams cells plaques LDL trapped to injury and accumulate fatty streaks accumulate and injury to the macrophages and combine become and covered accumulate intima engulf with lipids to fibrous by platelet in the injured lipoproteins form fatty plaques cap (red intima producing streaks thrombus foam cells deposition) These areas of atherosclerosis may eventually occlude the artery Impaired Circulation: Flow Turbulent or stagnant blood flow contributes to thrombus formation Common sites of altered blood flow: Bifurcations – region where vessel branches Aneurysms – local outpouchings in the vessel wall due to weakness Areas of venous stasis (condition of slow blood flow in the veins) Impaired Circulation: Blood http://www.nhlbi.nih.gov/health/health‐topics/topics/sca Hypercoagulability (excess clotting): unregulated formation of thrombi throughout the body Congenital: genetic mutations ‐ excess coagulant factors or deficient anticoagulant mechanisms Acquired : Autoimmune mechanisms that activate platelets and alter coagulation factors Certain types of cancer, or myeloproliferative disorders, such as thrombocythemia (excess platelets) Sickle cell anemia Polycythemia vera (too many RBCs are produced) Use of oral contraceptives Vascular changes in the late stage of pregnancy Impaired Circulation: Blood Thrombus formation outcomes: A. The thrombus continues to grow and occlude the vessel completely B. The thrombus is degraded by enzymes and decreases in size C. All or part of the thrombus breaks off and travels through the circulation  Strayer D, Rubin E. Rubin's Pathology: Clinicopathologic Foundations of Medicine. 7th ed. UK, Wolters Kluwer/Lippincott Williams & Wilkins; 2014 Impaired Circulation: Blood Thromboembolus: thrombus breaks off and travels Embolus: any plug of material that travels in the circulation and can obstruct the lumen of a vessel Thrombi Air/foreign material Neoplasm Microorganisms Amniotic fluid  Strayer D, Rubin E. Rubin's Pathology: Clinicopathologic Foundations of Impaired Circulation: Blood Medicine. 7th ed. UK, Wolters Kluwer/Lippincott Williams & Wilkins; 2014 Venous thromboemboli: Often originate: in the deep veins of the legs break off, travel along the vein lodge in the pulmonary arteries where the vessels narrow and bifurcate Arterial thromboemboli: Strayer D, Rubin E. Rubin's Pathology: Often originate: in the Clinicopathologic Foundations of Medicine. 7th ed. UK, Wolters Kluwer/Lippincott Williams & Wilkins; heart as atherosclerotic 2014 plaques travel to the legs, brain, intestines, lower extremities, or kidneys Impaired Circulation: Blood Infarct is an area of necrosis resulting from a sudden insufficiency of blood supply due to vessel obstruction loss of blood supply necrosis formation loss of function of the affected tissue Severity of the infarction depends on depends on the size and location of the emboli Small emboli: small and less significant areas of McCance KL, Huether S. Pathophysiology. 7th ed. N.S.W, Mosby; 2015 necrosis Areas with collateral circulation are capable of perfusing tissue around the obstructed vessel Larger emboli: occlude large vessels and their tributaries, and cause sudden death  Altered Perfusion The inability to adequately oxygenate tissues at the capillary level Factors that could alter perfusion include: Inadequate Inadequate ventilation perfusion  Inadequate Cardiac Output The heart is unable to successfully eject the necessary amount of blood to the pulmonary and systemic circulation 1. Changes in blood volume, composition, or viscosity 2. Impaired ventricular pumping 3. Structural heart defects (such as valve defects that allow leaking or regurgitation of blood) 4. Conduction defects that lead to an unresponsive heart rate and rhythm 5. Excessive or significantly reduced peripheral vascular resistance  Inadequate Cardiac Output Changes in blood volume, composition, or viscosity Volume and viscosity is altered: dehydration, or haemorrhage hypercoagulation (disseminated intravascular coagulation (DIC)) Composition altered: anemia altered oxygen transport there aren’t enough red blood cells to carry oxygen heart tries to move the small number of cells at a faster heart rate and becomes overtaxed  Inadequate Cardiac Output Impaired ventricular pumping Loss of muscle activity leads to the inability to move blood effectively forward through the arterial circulation This leads to congestion of venous blood and impaired venous return Heart failure : impaired ventricular pumping and venous insufficiency Failure of one ventricle increases the workload on the other Increased workload often leads to failure as well Inadequate Cardiac Output Occurs in about 1 in every Occurs in 500 births about 1 in every 1500 births  Inadequate Cardiac Output Valvular defects Congenital or acquired (infection, inflammation, trauma, and degeneration) Stenosis (narrowing of the valve) or regurgitation (incompetence of the valve) Most often affected: bicuspid (mitral) and aortic valves Valve open or close improperly McCance KL, Huether S. Pathophysiology. 7th ed. N.S.W, Mosby; 2015  Inadequate Cardiac Output Conduction defects: alter an optimal heart rate and rhythm Cardiac dysrhythmias are indicative of problems with maintaining an efficient heart rhythm problems with: SA node AV node cardiac cells that join the SA and AV nodes conduction systems in the atria or ventricles Without a regular, productive, efficient heart rhythm, the heart is unable to perfuse body tissues adequately Marieb EN, Hoehn KN. Human Anatomy & Physiology. 9th ed. Boston, Pearson Education; 2013 Inadequate Inadequate ventilation perfusion  Excessive Perfusion Demands Excessive demands, tissue metabolism : altered perfusion from lack of meeting this excessive demand All other aspects of ventilation and diffusion are functioning optimally Tissues demands are too much, perfusion not able to supply Cause: extreme and prolonged exertion metabolic alterations, as with hyperthyroidism anemia Inadequate Inadequate ventilation perfusion  General Manifestations of Altered Perfusion The general manifestations of altered perfusion depend on the cause Impaired cardiac output cyanosis, edema, shortness of breath, impaired growth, tachycardia, tachypnea, fatigue Changes in blood volume or peripheral vascular resistance hypotension or hypertension Obstructive processes myocardial or cerebral infarction: generally result in loss of function of that organ because of ischemia, pain, edema deep vein thrombosis: tenderness in the calf, especially with dorsiflexion of the foot Total occlusion of veins: edema, coolness, pallor, and cyanosis of the lower extremity General Manifestations of AlteredPerfusion Hemorrhage: ‐ leads to altered perfusion Skin manifestations of haemorrhage: Ecchymoses: bruises from superficial bleeding into the skin Petechiae: pinpoint hemorrhages Purpura: diffuse hemorrhages of the skin or mucous membranes Hematoma: larger accumulations of blood in the tissue Strayer D, Rubin E. Rubin's Pathology: Clinicopathologic Foundations of Medicine. 7th ed. UK, Wolters Kluwer/Lippincott Williams & Wilkins; 2014  General Manifestations of Altered Perfusion Altered heart sounds Two sounds (lub‐dup) associated with closing of heart valves First as AV valves close; beginning of systole Second as SL valves close; beginning of ventricular diastole Pause indicates heart relaxation Heart murmurs ‐ abnormal heart sounds; usually indicate incompetent or stenotic valves Normal heart sounds https://www.youtube.com/watch?v=FtXNn mifbhE Lilly, L. & Jung, H. (2011a). Locations of maximum intensity of common murmurs [Image]. In L. Lilly (Ed.), Pathyphysiology of Heart Disease. (5th ed.). Baltimore, Maryland: Lippincott Williams & Wilkins. https://www.nlm.nih.gov/medlineplus/ency/article/007201.htm Treatment measures Lifestyle Reduction of risks or modification of lifestyle: weight reduction, blood pressure management, stress reduction, smoking cessation, exercise, healthy nutrition, and diabetes management Pharmacologic Large group of various medications: to dilate blood vessels, reduce or increase blood pressure, control the heart rate/rhythm, increase myocardial contractility, reduce myocardial workload, or improve cardiac output ASA (aspirin) therapy: to reduce platelet aggregation and clot formation Thrombolytic agents: to break through an obstruction and revascularize myocardial tissue Pain medications: acute myocardial infarction Oxygen therapy: reduce hypoxemia Intravenous Fluid volume or blood replacement with severe hemorrhage or dehydration, administration of blood or fluids Treatment measures Surgery Coronary artery bypass grafting: to bypass an obstructed coronary artery Percutaneous transluminal coronary angioplasty: to compress fatty deposits in the coronary arteries and http://www.mayoclinic.org/tests‐ relieve the occlusion procedures/pacemaker/details/why‐its‐done/icc‐20198449 Laser angioplasty vaporizes fatty deposits with a hot‐tip laser device Repair valve defects, remove varicose veins, and drain excess fluid from the pericardial cavity Pacemaker placement A pacemaker may be placed to mechanically control heart rate and rhythm