Patho chapter 10 and 13 Cardiovascular and Respiratory Pathology

Erythrocytes and the RBC Life Cycle

• Red Blood Cells (RBCs) / Erythrocytes Production and Lifecycle:

  • Site of Production: RBCs are manufactured within the red bone marrow.

  • Hormonal Stimulation: The production of RBCs is stimulated by the hormone erythropoietin, which is released from the kidneys.

  • Lifespan: The average lifespan for a functional RBC is approximately $120\,days$.

  • Destruction Sites: Once their lifespan ends, RBCs are destroyed in the spleen, liver, and bone marrow.

  • Post-Destruction Recovery: After destruction, iron is recycled for further use by the body, while bilirubin is transported to the liver for processing.

Clinical Ranges for RBCs and Hemoglobin

• Normal Lab Reference Ranges:

  • Female RBC Count: $4.2\text{--}5.4\,million/mm^3$

  • Male RBC Count: $4.7\text{--}6.1\,million/mm^3$

  • Female Hemoglobin (Hgb): $12\text{--}16\,g/dL$

  • Male Hemoglobin (Hgb): $13.5\text{--}18\,g/dL$

Overview of Anemia

• Definition: Anemia is characterized by low RBC counts or low hemoglobin levels, resulting in decreased oxygen transport to body tissues.

• General Signs and Symptoms:

  • Fatigue and persistent tiredness.

  • Pallor (pale skin).

  • General weakness.

  • Dyspnea / Shortness of Breath (SOB).

  • Tachycardia (increased heart rate).

  • Dizziness.

  • Cold intolerance.

Specific Types of Anemia

• Iron-Deficiency Anemia:

  • Cause: Insufficient iron intake, chronic blood loss, poor dietary habits, or malabsorption.

  • Key Signs: Pallor, fatigue, tachycardia, SOB, brittle nails, and pica (unusual cravings for non-food items like ice or dirt).

  • Treatment: Administration of iron supplements and addressing the underlying cause of the iron loss.

• Pernicious / B12 Anemia:

  • Cause: A lack of intrinsic factor (required for B12 absorption), often due to autoimmune stomach issues or malabsorption.

  • Key Signs: Presence of abnormally large RBCs, fatigue, glossitis (inflamed tongue), numbness/tingling in extremities, and poor coordination.

  • Treatment: Vitamin B12 injections or high-dose oral B12.

• Aplastic Anemia:

  • Cause: Bone marrow failure triggered by radiation, chemotherapy, environmental toxins, specific viruses, or medications.

  • Key Signs: Pancytopenia (low RBCs, WBCs, and platelets), leading to fatigue, frequent infections, and bleeding tendencies.

  • Treatment: Removal of the triggering cause, blood transfusions, immunosuppressants, or bone marrow transplantation.

• Thalassemia:

  • Cause: An inherited disorder characterized by abnormal hemoglobin production.

  • Key Signs: General anemia signs, pallor, weakness, jaundice, and an enlarged spleen (splenomegaly).

  • Treatment: Frequent blood transfusions and iron chelation therapy to manage iron overload.

Sickle Cell Anemia: Inheritance and Pathophysiology

• Classification: Sickle Cell Anemia is an inherited chronic anemia caused by abnormal Hemoglobin S.

• Inheritance Pattern: Autosomal recessive.

  • Disease Genotype (SS): The individual has two sickle genes and manifests the disease.

  • Trait Genotype (AS): The individual is a carrier (Sickle Cell Trait).

  • Normal Genotype (AA): Two normal hemoglobin genes.

• Sickle Cell Trait Details: Carriers usually experience no symptoms unless subjected to severe physiological stress, such as extreme hypoxia, severe dehydration, or high-altitude environments.

• Pathophysiology of Sickling:

  • Hemoglobin becomes abnormal, causing RBCs to lose their flexibility and turn into stiff, sickle-shaped cells.

  • These cells block small blood vessels (vaso-occlusion), leading to poor oxygen delivery, significant pain, tissue damage, and gradual organ failure.

• Mnemonic for Triggers: "No $O_2$ + No $H_2O$ = SICKLE"

  • Trigger Factors: Low oxygen (hypoxia), dehydration, infection, fever, physiological stress, cold exposure, high altitude, strenuous exercise, and acidosis.

Complications and Symptoms of Sickle Cell Crisis

• Sickle Cell Crisis: Occurs when sickled RBCs obstruct blood flow, resulting in severe pain and potential systemic complications:

  • Tissue ischemia (lack of blood flow).

  • Infarction (tissue death).

  • CVA / Stroke (vessels in the brain are blocked).

  • Acute Chest Syndrome.

  • General organ damage, specifically renal damage and splenic issues.

• Understanding Specific Symptoms:

  • Jaundice: Caused by the rapid breakdown of RBCs (hemolysis), which elevates bilirubin levels.

  • Frequent Infections: Caused by damage to the spleen (autosplenectomy), rendering it unable to filter blood or fight infection effectively.

  • Splenomegaly: Sickled cells become trapped within the spleen's narrow vessels.

  • Congestive Heart Failure (CHF): Chronic anemia forces the heart to work significantly harder to pump limited oxygen.

• Prevention Strategies:

  • While the disease cannot be prevented after conception due to its genetic nature, crises can be minimized.

  • Utilize genetic counseling and parental screening.

  • Prevent crises through consistent hydration, oxygenation, infection prevention, and avoiding known triggers.

Polycythemia: Primary and Secondary

• General Definition: Polycythemia is a condition marked by too many RBCs, which increases blood viscosity (thickness) and elevates the risk for blood clots.

• Primary Polycythemia (Polycythemia Vera): A condition where the bone marrow produces excessive RBCs, and often excessive WBCs and platelets as well.

• Secondary Polycythemia: A compensatory mechanism where the body makes extra RBCs due to chronic low oxygen levels (e.g., COPD, high altitude, heart disease).

Hemophilia A

• Pathophysiology: A deficiency in clotting Factor VIII.

• Genetics: An X-linked recessive disorder that primarily affects males, while females typically act as carriers.

• Clinical Presentation: Prolonged bleeding after injury, spontaneous joint bleeding (hemarthrosis), and easy bruising.

• Treatment Protocol:

  • Factor VIII replacement therapy.

  • Desmopressin (DDAVP) for mild cases.

  • Avoidance: Patients must avoid aspirin and NSAIDs. Intramuscular (IM) injections should be avoided to prevent deep tissue bleeds.

• Inheritance Probabilities:

  • Carrier Mother ($X^HX^h$) and Normal Father ($X^HY$):

    • Son with hemophilia: $25\%$ of all children ($50\%$ of sons).

    • Carrier daughter: $25\%$ of all children ($50\%$ of daughters).

    • Neither affected nor carrier: $50\%$.

  • Man with Hemophilia ($X^hY$) and Carrier Woman ($X^HX^h$):

    • Child with hemophilia: $50\%$.

    • Carrier child: $25\%$.

    • Note: Carriers are exclusively female.

Disseminated Intravascular Coagulation (DIC)

• Definition: A complex disorder involving simultaneous pathological clotting and bleeding.

• Pathophysiology Process:

  1. The body forms numerous tiny clots within small vessels throughout the body.

  2. Platelets and clotting factors are rapidly consumed by this process.

  3. The patient begins to bleed uncontrollably because clotting factors are depleted.

  4. Microclots cause organ ischemia and potential multi-organ failure.

• Underlying Causes: Sepsis, trauma, cancer, obstetric complications, and severe shock.

• Signs and Symptoms: Oozing from IV sites, petechiae/ecchymosis, hematuria (blood in urine), hypotension, SOB, and organ failure.

• Diagnostic Labs:

  • $\downarrow\,Platelets$

  • $\uparrow\,PT/PTT$ (clotting times)

  • $\uparrow\,D\text{-}dimer$

  • $\downarrow\,Fibrinogen$

• Treatment: Treating the primary underlying cause, administration of blood products (platelets, fresh frozen plasma), and supportive care (oxygen).

Leukemia: Classifications and Manifestations

• Definition: Cancer of the white blood cell (WBC)-forming cells within the bone marrow.

• Pathophysiology: Bone marrow produces an overabundance of abnormal, immature WBCs (blast cells) that crowd out healthy RBCs and platelets.

• Blast Cells: Immature WBCs that are large, abnormal, and nonfunctional, meaning they cannot fight infection.

• Major Classifications:

  • Acute Leukemia: Characterized by a fast onset and a high number of immature blast cells.

  • Chronic Leukemia: Characterized by a slower onset and more mature (though still abnormal) cells.

  • Lymphocytic: Involves the lymphocyte cell line.

  • Myelogenous: Involves myeloid cells.

  • Specific Examples: ALL (Acute Lymphocytic), AML (Acute Myelogenous), CLL (Chronic Lymphocytic), CML (Chronic Myelogenous).

• Manifestations: Frequent infection, fatigue/anemia, bleeding/bruising, bone pain, fever, and enlargement of lymph nodes, spleen, or liver.

Opportunistic and Viral Respiratory Infections (PCP, SARS, COVID-19)

• Pneumocystis jirovecii Pneumonia (PCP):

  • Nature: An opportunistic pneumonia common in immunocompromised individuals.

  • High-Risk Groups: Individuals with HIV/AIDS (low $CD4$ counts), organ transplant recipients, chemotherapy patients, and those on long-term steroids.

  • Signs: Fever, dry cough, dyspnea, hypoxia, and fatigue.

  • Treatment: Antibiotics (specifically $TMP-SMX$), oxygen, and corticosteroids for severe cases.

• Severe Acute Respiratory Syndrome (SARS):

  • Cause: Coronavirus spread by respiratory droplets or contact.

  • Pathophysiology: Virus infects the respiratory tract → inflammation and lung damage → Alveoli fill with fluid/inflammatory cells → decreased gas exchange.

  • Blood Gas Changes: Early stages show hyperventilation resulting in respiratory alkalosis. Late/severe stages show respiratory failure resulting in respiratory acidosis.

  • Treatment: Isolation, oxygen, fluids, ventilation if required, and supportive care.

• COVID-19 Unique Characteristics:

  • Caused by the $SARS-CoV-2$ virus.

  • Utilizes a spike protein to enter host cells.

  • Capable of spreading before the onset of symptoms (asymptomatic transmission).

  • Complications include systemic inflammation, clotting issues, pneumonia, and severe hypoxia.

• Challenges with Unknown Infections: Healthcare control is difficult because workers may not know the spread mechanism, incubation period, duration of contagion, ideal isolation methods, or the most effective tests and treatments.

Tuberculosis (TB): Characteristics and Pathophysiology

• Agent: $Mycobacterium\,tuberculosis$

• Characteristics of the Bacteria:

  • Acid-fast bacteria with a waxy cell wall.

  • Slow-growing and airborne.

  • Capable of surviving inside macrophages and remaining dormant for long periods.

• Difficulty in Eradication: TB hides inside macrophages and forms granulomas. The waxy wall provides protection against the immune system and many treatments.

• High-Risk Populations: Close contacts of active cases, homeless individuals, those in shelters or prisons, immigrants from high TB areas, immunocompromised/HIV patients, older adults, healthcare workers, and malnourished individuals.

• Disease Progression:

  1. TB is inhaled into the lungs.

  2. Macrophages engulf the bacteria but cannot destroy them.

  3. The body walls off the bacteria into granulomas (also called tubercles).

  4. Bacteria may remain dormant or reactivate if immunity weakens.

Tuberculosis (TB): Clinical Manifestations and Treatment

• Classification of Infection:

  • Primary TB: The initial infection; often asymptomatic and may become latent.

  • Secondary TB: Reactivation of the bacteria; usually symptomatic and highly contagious.

• Classic Lesion: Granuloma/tubercle containing caseous necrosis.

• Signs/Symptoms:

  • Primary: Often none, or mild fever/fatigue with a positive skin test.

  • Secondary/Active: Cough lasting longer than $3\,weeks$, hemoptysis (coughing up blood), night sweats, weight loss, fever, fatigue, and chest pain.

  • Miliary TB: TB spreading via the bloodstream to multiple organs; life-threatening.

• Diagnosis of Active TB: Sputum culture (gold standard), acid-fast bacilli smear, NAAT testing, and chest x-rays.

• The Mantoux Test: A skin test (PPD). A positive result indicate exposure or infection but does not confirm active disease.

• Medication Management (RIPE Acronym):

  • Rifampin

  • Isoniazid

  • Pyrazinamide

  • Ethambutol

  • Rationale for Multi-drug Therapy: Kills bacteria in different phases and prevents antibiotic resistance.

  • Duration: Typically $6\,months$ or longer.

  • Contagion Status: Viewed as noncontagious after about $2\,weeks$ of effective therapy, with improving symptoms and/or negative sputum tests.

• Protection for Healthcare Workers: Use of N95 masks, negative-pressure rooms, airborne precautions, and hand hygiene.

Cystic Fibrosis (CF)

• Nature: An autosomal recessive genetic disorder involving defective chloride movement.

• Genetic Outcomes (Carrier Parents $Ff \times Ff$):

  • Child with CF ($ff$): $25\%$

  • Carrier child ($Ff$): $50\%$

  • Unaffected non-carrier ($FF$): $25\%$

  • If one parent has CF ($ff$) and one is a carrier ($Ff$), the chance for a child to have CF is $50\%$.

• Pathophysiology: Defective chloride transport prevents water from moving normally, leading to thick, sticky mucus secretions.

  • Respiratory Effects: Mucus blocks airways, traps bacteria, causing recurrent infections and bronchiectasis.

  • Digestive Effects: Pancreatic ducts are clogged, leading to poor digestion and malabsorption.

• Clinical Manifestations: Chronic cough, thick sputum, recurrent lung infections, wheezing, SOB, salty skin, poor weight gain, greasy bulky stools, barrel chest, and male infertility.

• Diagnosis: Newborn screening, sweat chloride test (primary), genetic testing, and pulmonary function tests.

• Treatment: Airway clearance, chest physiotherapy, bronchodilators, mucolytics, hypertonic saline, antibiotics, pancreatic enzymes, high-calorie/high-protein diet, and fat-soluble vitamins ($A, D, E, K$).

• Primary Cause of Death: Respiratory failure from chronic lung disease or infections.

Chronic Obstructive Lung Disorders

• Asthma: Reversible bronchospasm, inflammation, and mucus in the bronchi/bronchioles. Key signs: wheezing, cough, SOB, chest tightness. Treatment: Trigger avoidance, albuterol, and inhaled steroids.

• Emphysema: Destruction of the alveoli leading to air trapping and poor gas exchange. Key signs: Dyspnea, barrel chest, and pursed-lip breathing. Treatment: Smoking cessation, bronchodilators, and breathing exercises.

• Chronic Bronchitis: Chronic inflammation and excessive mucus in the bronchi. Key signs: Productive cough, cyanosis, wheezing, and frequent infections. Treatment: Smoking cessation, bronchodilators, antibiotics, and fluids.

• Memory Aid:

  • Asthma = Tight tubes

  • Emphysema = Damaged air sacs

  • Chronic Bronchitis = Mucus cough

Other Bronchial and Lung Disorders (Bronchiectasis, Pneumoconiosis)

• Bronchiectasis: Permanent dilation/widening of bronchi from chronic infection. Often seen in Cystic Fibrosis. Characterized by large amounts of purulent sputum and hemoptysis.

• Pneumoconiosis: Lung disease caused by inhaling dust particles (Coal dust, Silica, Asbestos). Leads to chronic inflammation and fibrosis. No cure exists for the fibrosis; treatment is supportive.

Pulmonary Edema

• Causes: Left-sided heart failure, MI, fluid overload, kidney failure, ARDS, high altitude, or inhalation injury.

• Pathophysiology: Fluid backs up into lung tissue and alveoli, preventing oxygen from crossing into the blood, leading to hypoxia and dyspnea.

• Signs: SOB, crackles (breath sounds), orthopnea, and pink frothy sputum.

• Pink Frothy Sputum Explanation: Fluid in the alveoli mixes with air, and small amounts of blood leak from the capillaries.

• Orthopnea: Difficulty breathing when lying flat. Patients must sit upright, which helps the fluid drain downward, easing the effort of breathing.

• Treatment: High Fowler’s position, oxygen/CPAP, Furosemide, and Nitroglycerin.

Pulmonary Embolus (PE)

• Definition: A blockage in a pulmonary artery, usually by a blood clot.

• Sources: Most originate from Deep Vein Thrombosis (DVT) in the legs or pelvis. Others include fat emboli, air emboli, amniotic fluid, tumor fragments, or septic clots.

• High-Risk Factors: Immobility, recent surgery, pregnancy, oral contraceptives/estrogen, cancer, obesity, and smoking.

• Pathophysiology: The clot blocks blood flow; ventilation occurs, but perfusion does not. This results in hypoxemia and increased right-sided heart pressure.

• Signs: Sudden dyspnea, pleuritic chest pain, tachycardia, tachypnea, anxiety, and hemoptysis.

• Drug Therapy: Heparin, Warfarin, DOACs, or Alteplase/tPA for massive PE.

Pleural and Alveolar Disorders (Atelectasis, Effusion, Pneumothorax)

• Atelectasis: Collapsed or airless alveoli. Leads to decreased breath sounds, dyspnea, and fever.

• Pleural Effusion: Build-up of fluid in the pleural space. Signs include dyspnea, dull percussion sounds, and decreased breath sounds.

• Pneumothorax: Build-up of air in the pleural space. Signs include sudden sharp chest pain, absent breath sounds, and hyperresonance on percussion.

• Memory Aid:

  • Effusion = Fluid (Dull sounds)

  • Pneumothorax = Air (Hyperresonant sounds)

Flail Chest and Acute Respiratory Failure

• Flail Chest: Several ribs broken in multiple places, creating a loose chest segment.

  • Primary Sign: Paradoxical movement (injured section moves inward during inspiration and outward during expiration).

  • Complications: Pulmonary contusion and respiratory failure.

• Acute Respiratory Failure:

  • Causes: COPD exacerbation, pneumonia, ARDS, PE, trauma, or drug overdose.

  • Clinical Signs: Severe dyspnea, confusion/restlessness, cyanosis, Low $O_2$, High $CO_2$, and abnormal Arterial Blood Gases (ABGs).

Summary Cram Sheet

• Anemia: Low oxygen-carrying capacity.

• Sickle Cell: Blocked vessels + pain crisis.

• Polycythemia: Thick blood.

• Hemophilia A: Factor VIII deficiency.

• DIC: Clotting uses factors up → subsequent bleeding.

• Leukemia: Abnormal WBCs crowd bone marrow.

• TB: Airborne, slow-growing, hides in granulomas.

• CF: Thick sticky mucus impacting lungs/pancreas.

• Asthma: Reversible bronchospasm.

• Emphysema: Destroyed alveoli.

• Chronic Bronchitis: Constant mucus cough.

• Pulmonary Edema: Fluid in alveoli.

• PE: Clot blocking lung blood flow.

• Pleural Effusion: Excess fluid in pleural space.

• Pneumothorax: Air in pleural space.

• Flail Chest: Paradoxical chest movement.