Mod 5 Modules

Fundamentals and Definitions of Perfusion

• Definition of Perfusion: Refers to the flow of blood through arteries and capillaries, which delivers essential nutrients and oxygen to cells while removing waste products.

• Central Perfusion:

  • Represents the force of blood movement generated by cardiac output.

  • It requires adequate cardiac function, sufficient blood pressure, and adequate blood volume.

  • Cardiac Output (CO): Defined as the volume of blood ejected by the heart (specifically the left ventricle) each minute.

• Tissue or Local Perfusion:

  • Represents the volume of blood that flows to a specific target tissue.

  • It requires patent (open) vessels, adequate hydrostatic pressure, and capillary permeability.

Cardiac Anatomy and Blood Flow

• Surface Anatomy - Anterior View:

  • Right Side: Superior vena cava, Right pulmonary artery, Right atrium, Tricuspid valve, Inferior vena cava, Right ventricle.

  • Left Side: Left pulmonary artery, Pulmonic valve location, Left atrium, Aortic valve location, Mitral valve location, Left ventricle.

• Surface Anatomy - Posterior View: Identifies the locations of the Left pulmonary artery, Right pulmonary artery, Coronary sinus, and Right ventricle.

• Blood Flow Path: Unoxygenated blood (represented by dark arrows) enters via the vena cavae, moves through the right heart to the lungs; oxygenated blood (represented by white arrows) returns from the lungs to the left heart and is pumped to the systemic circulation.

Physiological Variations and Impairments

• Impaired Central Perfusion:

  • Occurs when cardiac output is inadequate to meet the body's needs.

  • Results in a systemic effect where oxygenated blood fails to reach body tissues efficiently.

  • Severe impairment is associated with shock.

  • If left untreated, it results in ischemia, cellular injury, and eventual cell death.

• Impaired Tissue (Local) Perfusion:

  • Associated with loss of vessel patency, vessel permeability, or inadequate central perfusion.

  • Results in localized effects (impaired blood flow to a specific affected tissue).

  • Leads to ischemia and cell death if the correction is not made.

Arterial vs. Venous Insufficiency

• Arterial Insufficiency / Peripheral Arterial Disease (PAD):

  • Pathophysiology: Narrowing of arteries caused by atherosclerosis (plaque buildup), commonly affecting the pelvis and legs.

  • Clinical Symptoms: Cramping, pain, tired legs, or hip muscles that worsen during walking or activity and subside with rest (intermittent claudication).

  • Ulcer/Lesion Characteristics:

    • Location: End of toes, top of feet (dorsum), or lateral ankle region (malleolus).

    • Appearance: Very little drainage, little tissue granulation (pale/light pink or necrotic/black).

    • Margins: Deep, "punched out" appearance with noticeable round margins.

• Venous Insufficiency / Peripheral Venous Disease (PVD):

  • Pathophysiology: Inadequate return of venous blood from the legs back to the heart.

  • Clinical Symptoms: Legs feel tired, heavy, achy, or cramped; pain worsens when standing and improves with leg elevation and activity.

  • Ulcer/Lesion Characteristics:

    • Location: Medial parts of lower legs and the medial ankle region.

    • Appearance: Swollen with drainage; granulation is present (deep pink to red).

    • Margins: Shallow with irregular edges.

Risk Factors for Impaired Perfusion

• Populations at Greatest Risk:

  • Older adults.

  • Low-income and low-educational level individuals.

  • Men.

  • African Americans.

  • Individuals with a significant family history.

• Modifiable Risk Factors:

  • Smoking and nicotine use.

  • Physical inactivity and sedentary lifestyle.

  • Obesity.

  • Psychological factors and high stress levels.

  • Poor diet.

Clinical Noticing: Cues and Assessment

• General Cues (Adults): Pain, syncope (fainting), dizziness, dyspnea (shortness of breath), edema, bleeding, bruising, and fatigue.

• Cues in Infants: Poor feeding, poor weight gain, failure to thrive, and a dusky skin color.

• Cues in Toddlers/Children: Squatting (often to relieve dyspnea), fatigue, and developmental delays (failure to reach milestones).

• Physical Assessment Components:

  • Vital Signs: Blood pressure, heart rate, etc.

  • Inspection: Observing skin color, presence of edema, and hair loss on extremities.

  • Palpation: Checking for skin temperature and peripheral pulses.

  • Auscultation: Listening to heart sounds and murmurs.

• Pulse Palpation Sites: Carotid, Brachial, Radial, Ulnar, Femoral, Popliteal, Posterior tibial, and Dorsalis pedis.

Diagnostics and Prevention

• Common Diagnostic Tests:

  • Labs: Cardiac enzymes/markers (such as Troponin), serum lipids, complete blood count (CBC), blood coagulability, and bone marrow biopsy.

  • Cardiac Studies: Electrocardiogram (ECG), exercise or pharmacologic cardiac stress tests.

  • Radiography: Chest x-ray, ultrasound, arteriogram, and venogram.

• Primary Prevention: Focuses on lifestyle changes including smoking/nicotine cessation, healthy diet, regular exercise, and weight control.

• Secondary Prevention (Screening):

  • Blood Pressure Screening: Community programs and public education on risk factors.

  • Goal: Identify high-risk individuals and promote health-promoting behaviors.

Pharmacotherapy and Interventions

• Common Perfusion Medications:

  • Vasodilators, Vasopressors, Diuretics, Antidysrhythmics, Cardioglycosides.

  • Anticoagulants, Antiplatelet agents, Thrombolytics, and Antilipidemics.

• Surgical Procedures - Central Perfusion: Pacemaker insertion, electrical cardioversion, ablation therapy, intraaortic balloon pump, cardiac valve surgery, cardiac transplant, and percutaneous coronary intervention (PCI).

• Surgical Procedures - Tissue Perfusion: Bypass and/or graft surgery, stent placement, angioplasty, and endarterectomy.

Hypertension (High Blood Pressure)

• Definition: The force of blood against artery walls is consistently too high, forcing the heart to work harder.

• AHA Blood Pressure Categories:

  • Normal: $< 120/80\,mm\,Hg$.

  • Elevated: $120 - 129\,mm\,Hg$ systolic AND $< 80\,mm\,Hg$ diastolic.

  • Stage 1 Hypertension: $130 - 139\,mm\,Hg$ systolic OR $80 - 89\,mm\,Hg$ diastolic.

  • Stage 2 Hypertension: $\ge 140\,mm\,Hg$ systolic OR $\ge 90\,mm\,Hg$ diastolic.

  • Severe Hypertension: $\ge 180\,mm\,Hg$ systolic AND/OR $\ge 120\,mm\,Hg$ diastolic.

  • Hypertensive Emergency: $\ge 180/120\,mm\,Hg$ accompanied by symptoms like chest pain, shortness of breath, back pain, numbness, weakness, vision changes, or difficulty speaking.

• Primary (Essential) Hypertension: No clear cause. Risk factors include old age, obesity, salt-heavy diet, and sedentary lifestyle. It is known as the "Silent Killer" because it usually has no symptoms.

• Secondary Hypertension: Caused by an underlying condition such as atherosclerosis, low renal blood flow, sleep apnea, hyperthyroidism, traumatic brain injury (TBI), or diabetes.

• Treatment Management: Dietary management, regular exercise ($30\,minutes$ daily as tolerated), stress management, tobacco avoidance, and antihypertensive meds (diuretics for volume control).

• Duration of Therapy: Patients with essential hypertension require medication for the rest of their lives to maintain stable control.

Heart Failure (CHF)

• Definition: "Pump failure"; the inability of the heart to work effectively as a pump.

• Etiology: Systemic hypertension is the most common cause; one-third of MI patients develop HF; valvular dysfunction causes pressure/volume overload.

• Left-Sided Heart Failure:

  • Causes: Hypertension, coronary artery disease (CAD), myocardial infarction (MI), and valvular disease.

  • Clinical Presentation: Weakness, fatigue, dizziness, acute confusion, breathlessness, oliguria, nocturia, hacking cough, frothy pink-tinged sputum, and lungs with crackles or wheezes.

• Right-Sided Heart Failure:

  • Causes: Left ventricular failure, right ventricular MI, or pulmonary hypertension.

  • Pathophysiology: Right ventricle cannot empty; volume and pressure increase in the venous system.

  • Clinical Presentation: Jugular vein distention (JVD), increased abdominal girth, dependent edema (legs/ankles), hepatomegaly, ascites, and nocturia.

  • Monitoring: Weight is the most reliable indicator of fluid gain/loss.

• Diagnostics:

  • BNP (B-type Natriuretic Peptide): Elevated (Normal range: $0 - 100\,pg/mL$).

  • Echocardiography: Considered the best diagnostic tool for heart failure.

• Management:

  • Gas Exchange: High Fowler's position, monitor RR every $1 - 4\,hours$, goal $O_2$ saturation $\ge 90\%$.

  • Preload Reduction: Diuretics, venous vasodilators, nutrition therapy.

  • Afterload Reduction: ACE inhibitors, ARBs, Human BNP.

  • Contractility Enhancement: Digoxin (Cardioglycoside), Beta-blockers, Aldosterone antagonists.

  • Pulmonary Edema Warning Signs: Crackles at bases, dyspnea at rest, disorientation. Treatment includes rapid-acting diuretics, IV morphine, and Nitroglycerin.

Cardiac Conduction and ECG Interpretation

• Conduction Path: SA node $\rightarrow$ AV node (delay) $\rightarrow$ Bundle of His $\rightarrow$ Right and Left Bundle Branches $\rightarrow$ Purkinje fibers.

• ECG Waveforms:

  • P wave: Atrial depolarization; firing of the SA node. Should not exceed $3$ small boxes ($0.12\,mV/3\,mm$) in height; must be rounded and symmetrical.

  • PR Interval: Atrial depolarization and the delay in the AV node ($Beginning of P to beginning of QRS$). Normal range: $0.12\,s$ to $0.20\,s$.

  • QRS Complex: Ventricular depolarization. Normal duration: $0.06\,s$ to $0.10\,s$. A width $> 0.12\,s$ indicates a bundle branch block (BBB) or ventricular rhythm.

  • ST Segment: Early ventricular repolarization. Elevation indicates myocardial injury; depression indicates ischemia, digoxin use, or reciprocal changes.

  • T wave: Ventricular repolarization. Peaked T-waves indicate hyperkalemia; inversion indicates ischemia.

  • QT Interval: Total time for ventricular depolarization and repolarization ($Beginning of QRS to end of T$). Normal: $0.32\,s$ to $0.50\,s$. Prolonged QT increases risk for lethal dysrhythmias ($Torsades de Pointes$).

• Analysis Steps: Determine rate, determine rhythm regularity, analyze P waves, measure PR interval, measure QRS duration.

Specific Dysrhythmias

• Sinus Tachycardia: Rate $100 - 150\,beats/min$. Treat the cause (fever, pain, anxiety, hyperthyroidism).

• Sinus Bradycardia: Rate $< 60\,beats/min$. Treat with Atropine or pacing if symptomatic.

• Atrial Fibrillation (AFib):

  • Characteristics: Erratic impulse formation; no discernible P waves; "irregularly irregular" ventricular rate; loss of the "atrial kick."

  • Risks: High risk for systemic emboli and stroke.

  • Treatment: Anticoagulants (Warfarin, Pradaxa, Xarelto, Eliquis), rate control (Cardizem, Beta-blockers, Digoxin), and rhythm control (Amiodarone, Flecainide).

  • Non-surgical: Cardioversion, radiofrequency catheter ablation.

Myocardial Infarction (MI) and ACS

• Acute Coronary Syndrome (ACS): Spectrum including unstable angina and acute MI.

• Chronic Stable Angina: Ischemia limited in duration; does not cause permanent damage; relieved by rest/Nitroglycerin.

• Unstable Angina: New onset or worsening angina; ST changes on ECG but normal Troponin/CK levels.

• Myocardial Infarction Types:

  • NSTEMI: Non-ST elevation MI; subendocardial ischemia.

  • STEMI: ST-segment elevation MI; transmural ischemia; represents a surgical emergency.

• Diagnostic Markers: Troponin T and Troponin I are the primary laboratory indicators of myocardial damage.

• Acute Management: Pain management (Nitroglycerin, Morphine, Oxygen), Semi-Fowler's position, Percutaneous Coronary Intervention (PCI/Stents).

• Complications: Cardiogenic shock (symptoms: cold/clammy skin, poor pulses, tachycardia, hypotension, decreased urine output).

Peripheral Arterial Disease (PAD) Specifics

• The Six P's of Arterial Insufficiency: Pain, Pallor, Pulselessness, Paresthesia, Paralysis, Poikilothermia (coolness).

• Assessment Cues: Intermittent claudication, hair loss, dry/scaly skin, thickened toenails, and "dependent rubor" (redness when legs hang down).

• Testing: Ankle-brachial index (ABI) compares blood pressure in the ankle to blood pressure in the arm.

Questions & Discussion

• Q: What instruction is included for a simvastatin prescription?

• A: Liver enzyme levels should be monitored every few months. Common side effects include fatigue and myalgias.

• Q: Which OTC medications should a patient on Furosemide and Clonidine avoid?

• A: Decongestant cough preparations, as they can cause increased dizziness, confusion, and motor coordination impairment.

• Q: What is the desired response for Propranolol in HTN treatment?

• A: Decreased cardiac rate with a resulting decrease in cardiac output.

• Q: A patient has a BP of $150/96\,mm\,Hg$, is $20\,lb$ overweight, and cholesterol is $240\,mg/dL$. What is the priority?

• A: Refer to a doctor for follow-up and medications alongside lifestyle changes.

• Definition of Perfusion: Refers to the flow of blood through arteries and capillaries, which is critical as it delivers essential nutrients and oxygen to cells, tissues, and organs, while also removing carbon dioxide and other metabolic waste products. Adequate perfusion is essential for maintaining cellular function and homeostasis throughout the body.

• Central Perfusion:

  • Represents the force of blood movement generated by cardiac output, which is the amount of blood the heart pumps in one minute. Central perfusion is necessary for delivering blood to the body's vital organs, including the heart and brain.

  • It requires adequate cardiac function (the heart must be effective as a pump), sufficient blood pressure to propel blood through the vessels, and adequate blood volume to fill the circulatory system.

  • Cardiac Output (CO): Defined as the volume of blood ejected by the heart (specifically the left ventricle) each minute, usually expressed in liters per minute (L/min). It is calculated by multiplying heart rate (HR) by stroke volume (SV), which is the amount of blood pumped with each heartbeat.

• Tissue or Local Perfusion:

  • Represents the volume of blood that flows to a specific target tissue, ensuring that cellular metabolism occurs effectively by transporting oxygen and nutrients directly to those cells.

  • It relies on patent (open) vessels, adequate hydrostatic pressure to facilitate blood flow, and capillary permeability for the exchange of nutrients and waste products between blood and tissues.

  • Poor local perfusion can lead to ischemia, which if severe and prolonged, can result in tissue necrosis or death.