Tuesday, October 10 (ellen)

Respiratory Pathologies Continued – Tuesday, October 10, 2006 Pulmonary Embolism ~ basically a stroke to the lungs ~ sudden lodgment of a blood clot in a pulmonary artery with subsequent obstruction of blood supply to lung parenchyma ~ M/C (most common): thrombus migrates elsewhere from leg/pelvic veins ~ lower lobes of lung, 4 times more likely to get pulmonary embolism than upper lobes ~ usually embolism are lodged in large or intermediate, elastic or muscular, arteries ~ only <35% of them lodge in smaller arteries ~ fractures – broken bone, fat leaks out from bone marrow and it will travel in the bloodstream ~ amniotic fluid emboli – between mother and child ~ air embolus – why we flick air out of needles before the needles are injected ~ decrease or lack of blood flow – ischemia  hypoxia ~ can also have hypoxia without ischemia (ex: when there is carbon dioxide poisoning, high altitude, strangulation, nutritional depletion, and hemorrhage) Pulmonary Embolism Pathophysiology ~ massive emboli may cause death within minutes to hours, even before infarction happens ~ there is increased risk with hematologic disorders, immobilization, or post hip/knee replacement ~ usually there are no predisposing factors found ~ things that have effect on risk: pulmonary hemodynamics, gas exchange, and mechanics Cor Pulmonale ~ right ventricular enlargement secondary to a lung disorder that produces pulmonary artery hypertension ~ remember: the right ventricle carries deoxygenated blood ~ the enlargement occurs because of a lung disorder ~ the hypertension occurs because there is fluid squeezed from tissues into lung ~ basically cor pulmonale is a heart problem that is secondary to a lung problem ~ directly caused by alterations in pulmonary circulation  leads to pulmonary arterial hypertension ~ ends up increasing mechanical load on right ventricle emptying ~ afterload: tension produced by a chamber of the heart in order to contract. Can also be described as the pressure that the chamber of the heart has to generate in order to eject blood out of the chamber. ~ all else held equal, then as after load increases, cardiac output decrease ~ if no specific chamber is mentioned, afterload generally refers to left ventricle ~ Hypertension will increase the left ventricular afterload because the left ventricle has to work harder to eject blood into aorta. Likely due to the fact that the aortic valve won’t open until the pressure generated in the left ventricle is higher then the elevated blood pressure

~ compared to preload, which is volume of blood present in ventricle of heart after passive filling and atrial contraction. ~ Starling’s Law of Heart: the more the ventricle is filled with blood during diastole, the greater the volume of ejected blood during resulting systolic contraction. This basically means that the force of contraction will increase as the heart is filled with more blood. It is also a direct consequence of the effect of an increasing load in a single heart muscle fiber. ~ Acute cor pulmonale – usually from massive pulmonary embolization ~ chronic cor pulmonale – usually caused by COPD (chronic bronchitis, emphysema, etc) ~ keep in mind: upstream to an embolism, there’s increase BP = HTN ~ downstream to an embolism, there’s decrease BP – ischemia Primary Pulmonary Hypertension ~ a very uncommon disease of unknown cause ~ involves medium and small pulmonary arteries, resulting in right ventricular failure or fatal syncope 2-5 years after detection ~ see constriction and narrowing leading to reduced compliance and elasticity ~ women 2 times more than men ~ progressive excertional dyspnea occurs in more than 95% of the cases Respiratory Tract Infection ~ Gram +ve bacteria: generally Staph aureus or Strep pyogenes ~ Staph aureus infections: STOIC (scalded skin syndrome, toxic shock syndrome, osteomyolitis, impetigo, carbuncle) ~ Strep pyogenes infections: SEARS (strep throat, erysipelas, acute glomerulonephritis, rheumatic fever, scarlet fever) Acute URTI – Pharyngitis ~ acute inflammation of the pharynx ~ usually viral, but can be group A β-hemolytic strep or Mycoplasma pneumoniae, Chlamydia pneumoniae, or other bacteria ~characterized by sore throat and pain when swallowing Acute URTI – Laryngitis ~ inflammation of the larynx ~ m/c cause is viral ~ excessive use of voice, allergic reactions, and cigarette smoke  acute or chronic laryngitis ~ main symptom – unnatural voice change URTI – Acute Bronchitis ~ acute inflammation of tracheobronchial tree ~ generally self-limited w/ eventual complete healing and return of function ~ serious in patient’s with chronic lung or heart disease, or if debilitated ~ airflow obstruction is a common consequence

~ critical complication: pneumonia URTI – Acute Bronchitis ~ acute infectious bronchitis: increase in prevalence in winter ~ may develop after a common cold, often with secondary bacterial infection ~ malnutrition + air pollution are predisposing factors ~ acute irritative bronchitis – mineral and vegetable dusts, chemical fumes, ozone and nitrogen dioxide, tobacco LRTI – Pneumonia ~ aka pneumonitis ~ acute infection of lung parenchyma including alveolar spaces and interstitial tissues ~ may affect an entire lob (lobar pneumonia), segment of lobe (segmental or lobular pneumonia), alveoli contiguous to bronchi (bronchopneumonia), or interstitial tissue (interstitial pneumonia) ~ use x-ray to distinguish Pneumonia – Etiology ~ bacteria is the most common cause in adults over 30 yoa ~ s. pneumonia is the most common cause ~ others: s. aureus, h. influenze, legionella pneumophila, pseudomonas aeruginosa, moraxella catarrhalis, and klebsiella pneumoniae ~ mycoplasma pneumoniae: young adults, increases in spring ~ infants and children – RSV (respiratory syncitial virus), parainfluenza, and influenza A and B viruses ~ some bacteria secrete IgA protease – can kill your IgA defenses ~ transmission by inhaling droplets small enough to reach alveoli and aspirating secretions from upper airways ~ also by hematogenous or lymphatic dissemination and direct spread from contiguous infections ~ predisposing factors: URTI, alcoholism, institutionalization, smoking, heart failure, COPD, age extremes, debility, immunocompromised ~ alcoholism decrease B vitamin absorption, especially thiamin ~ old people have much more shallow breaths, therefore more CO2 stuck inside Pneumococcal Pneumonia ~ caused by Streptococcus pneumoniae ~ accounts for 2/3 of bacteremic community – acquired pneumonias ~ generally occurs sporadically, but usually during winter in persons at age extremes ~ 5-25% of healthy persons are carriers, highest in children and parents of young children, in the winter ~ > 80 stereotypes ~ pneumococci usually reach lungs by inhalation or aspiration ~ the droplets lodge in bronchioles, proliferate, and initiate an inflammatory process ~ process starts in alveolar spaces with an outpouring of protein-rich fluid

~ fluid is now a culture medium for bacteria and helps them spread to neighbouring alveoli  get lobar pneumonia ~ congestion – earliest stage of lobar pneumonia ~ extensive serous exudation, vascular engorgement, rapid bacterial proliferation ~ red hepatization – liver-like appearance of consolidated lung ~ airspaces filled with PMN’s, see vascular congestion, extravasation of RBCs causes a reddish discolouration ~ gray hepatization – fibrin accumulation associated with inflammatory WBCs and RBCs in various stages of disintegration ~ alveolar spaces packed with an inflammatory exudates ~ resolution – resorption of the exudates Viral Pneumonia ~ virus – strand of DNA or RNA in a protein coat ~ binds and internalizes into the host cell and integrates with host DNA to start replicating itself ~ also uses host protein machinery to make the viral protein capsule so it can bud out of the host cell ~ M/C infants and children: RXV, parainfluenza and influenza A and B ~ among otherwise healthy adults, usually only influenza A and B viruses ~ although uncommon, pneumonia in adults is caused by adenovirus, varicella-zoster virus, Epstein-Barr virus, coxsackievirus (hand-foot-mouth disease), and Hantavirus ~ adenovirus: adenoviridae family, pathogenic to humans cause conjunctivitis, URTI, cystitis, GI infection ~ appears as acute and symptomatic period, then latent stages in tonsils, adenoids, and other lymphoid tissues ~ viruses invade bronchiolar epithelium  causes bronchiolitis ~ infection may extend to pulmonary interstitium and alveoli, causing pneumonia ~ affected areas congested possibly hemorrhagic ~ inflammatory reaction composed of mononuclear cells, fibrin, and some neutrophils ~ in severe cases, may see hyaline membranes Pneumonia caused by Pneumocystis carinii ~ p. carinii – fungus (used to be classified as protozoan) ~ disease only in immunocompromised ~ m/c with decrease cell mediated immunity as in hematologic malignancies, lymphoproliferative diseases, cancer chemotherapy, and AIDS Pneumonia due to Pneumocystis carinii HIV infection ~ approx. 30% of patients with HIV infection have P. carinii pneumonia as initial AIDSdefining diagnosis ~ > 80% of AIDS patients have this infection at some time if prophylaxis is not given ~ patients with HIV infection become vulnerable to P. carinii when CD4 helper T cell count is < 200microL Mycoplasma Pneumonia

~ mycoplasma – bacteria, without cell wall ~ m/c pathogen of lung infections aged 5-35 yo ~ maybe responsible for epidemics that spread slowly because it has a 10-14 day incubation period ~ spread may involve close contacts in closed populations ~ mycoplasmia pneumonia is also called – primary atypical pneumonia or Eaton agent pneumonia ~ it attaches to and destroys ciliated epithelial cells of respiratory tract ~ microscopically – produces interstitial pneumonitis, bronchitis, and bronchiolitis ~ peribronchial areas infiltrated with plasma cells and small lymphocytes ~ within bronchial lumina – neutrophils, macrophages, firbrin strands, and epithelial cell debris Fungal Pneumonia ~ primarily caused by Blastomyces dermatitidis, Histoplasma capsulatum, or Coccidioides immitis ~ less commonly by Sporothrix schenckii or Cryptococcus, Aspergillus, or Mucor sp ~ may be a complication of antibacterial therapy, especially in patients with altered host defense mechanisms Histoplasmosis ~ aka Mississippi or Ohio Valley Fever ~ due to infection with dimorphic endemic fungi – Histoplamsa capsulatum ~ dimorphic yeast – mycelial form (in soil) or yeast form (infects humans) ~ majority of acute cases follow subclinical and benign course in normal host cells ~ if immunosuppressed, children less then 2yo, elderly, and ppl exposed to large inoculum – can be potentially fatal Coccidiomycosis ~ C. immitis – dimorphic soil fungi limited geographically to San Joaquin valley region ~ acquire by inhalation ~ initially in pulmonary areas but can move to other systems and organs ~ thru blood or lymph or direct contact ~ can infect skin, bones, joints, lymph nodes, adrenal glands, and CNS ~ vulnerable: immunocomprised and farmers Pulmonary Hypertension ~ pulmonary pressure reaches one fourth of systemic levels ~ usually it’s about 1/8 of systemic levels ~ most frequently secondary to structural cardiopulmonary conditions that increase: ~ 1) pulmonary blood flow or pressure (or both) or ~ 2) pulmonary vascular resistance or ~ 3) or left heart resistance to blood flow ~ pathologies that would cause the above conditions: ~ 1) COPD ~ 2) Heart disease – congenital or acquired

~ 3) Recurrent thromboemboli ~ 4) autoimmune disorders Pulmonary Sclerosis ~ pulmonary insufficiency due to systemic sclerosis ~ chronic disease of unknown etiology characterized by abnormal accumulation of fibrous tissue in the skin and multiple organs Pulmonary Infarction ~ necrosis in a part of lung caused by an obstruction in a branch of a pulmonary artery ~ occurs within 24 hours after formation of pulmonary embolus ~ symptoms include: pleural infusion, hemoptysis, leukocytosis, fever, tachycardia, atrial arrhythmias, striking distension of neck veins Tuberculosis 13-33 (can’t find much info on this one…if anyone knows, let me know and I’ll reupload it) Candidiasis ~ infection that can cause endocarditis as well as infection in KI, SP, LV, and LU ~ especially in debilitated patients