Flashcards in Exam 1 -- Pulmonary System Deck (156):
What are the roles of the pulmonary system?
Acquire O2, get rid of CO2, and provide fast adjustment to blood pH.
What factors are important to good lung function?
Good blood flow, good ventilation, high lung surface area, and a match between where the air is in the lungs and which capillaries are carrying the blood.
True or false: as soon as the bronchi enter the lungs, air exchange begins to take place.
False; there is no air exchange through the first 18 bifurcations.
What features contribute to the lung's immune response?
Lymph system is involved (enters at the hilum), cilia in the bronchi help get mucous and foreign substances out, cough reflex, mucous (to trap the foreign particles), and phagocytosis (if we can't get the foreign particle out).
Alveoli have thin walls and a single layer of epithelial cells, to aid in gas exchange. What role does surfactant play in the alveoli?
It keeps the alveoli from collapsing and allows them to open easier.
Pulmonary capillaries surround each alveoli and are lined with a single layer of endothelial cells, to allow for easy and fast gas exchange. What influences capillary size?
If the O2 levels in the alveoli are low, or if they are high enough in the capillary, the lumen will contract because there is no reason to shunt blood that direction. Conversely, if there is high O2 in the alveoli but low in the capillary, the lumen will relax to shunt blood to where the O2 is. This is how blood flow is "matched" to where oxygen happens to be in the lungs.
True or false: the diaphragm is dome shaped with contraction, and returns to a flat shape upon relaxation.
False; it is dome-shaped at rest. When it contracts, it flattens and moves downward, to put negative pressure on the lungs during inspiration.
True or false: the accessory muscles of inspiration usually contribute only little to inspiration.
True; though some disease processes cause these to be more important.
Though expiration is mainly achieved through relaxation of the diaphragm, what inherent tendency of the lung tissue helps?
Elastic recoil acts to help the lungs snap back to their original shape.
What is considered a normal respiratory rate for an adult?
12-19 cycles per minute
What is considered a normal respiratory rate for a child?
up to 20 cycles per minute
What is considered a normal respiratory rate for a newborn?
up to 44 cycles per minute
How many breaths per minute is considered bradypnea? Tachypnea?
10 or less is bradypnea, 20 or greater is tachypnea.
What effect does the sympathetic nervous system have on the lungs?
Very mild arteriolar constriction, bronchial smooth muscle dilation, and inhibition of mucous glands.
What effect does the parasympathetic nervous system have on the lungs?
Bronchial smooth muscle constriction and stimulation of mucous glands.
Peripheral and central chemoreceptors both affect the respiratory rate. Which has the greater effect, and which blood gas is the major modifier of its actions?
Central have the most effect (85%). Central receptors are mainly influenced by blood CO2 levels. Higher CO2 levels or increased acidity trigger a reflex to increasing the breathing rate and depth.
Peripheral chemoreceptors would trigger increased respiration in resonse to what change in the blood?
Low O2 levels, high CO2 levels, or increased acidity.
What mechanoreceptors can help modify respiration? Which of these is involved in the matching of blood and O2-rich lung areas?
Stretch receptors in chest wall and airways (cause expiration if overinflation), irritant receptors in airways (cough), and J receptors (in lung periphery; these make the match between blood and lung).
What are the two common symptoms of lung disease?
Dyspnea (SOB) and chronic cough (phlegm and blood)
Chest pain is not one of the common signs of most lung conditions. Which three of the conditions discussed do feature chest pain?
Sarcoidosis, tuberculosis, and histoplasmosis (chronic pulmonary).
What testing can be used in the diagnosis of lung diseases?
X-ray (for structural abnormalities or trapped air), pulmonary angiography (for emboli), pulse oximetry (for hemoglobin saturation), spirometry (for rates, volumes, and easy of respiration).
Which lung volumes/capacities can be measured directly?
Expiratory reserve volume, tidal volume, and inspiratory reserve volume
Define: tidal volume
The volume of air expired and inspired with normal breathing.
Define: inspiratory reserve volume
The extra volume of air that can be brought into the lungs with effort.
Define: expiratory reserve volume
The extra volume of air that can be forcefully expelled from the lungs
Define: vital capacity
The volume of air that includes everything from the expiratory reserve volume through the inspiratory reserve volume. (VC = IRV + TV + ERV)
Which lung volumes/capacities are measured indirectly (mathematically)?
Functional residual capacity, residual volume, and total lung capacity.
Define: functional residual capacity.
The volume of air remaining in the lungs at the end of normal expiration.
Define: residual volume
The volume of air remaining in the lungs even after forceful expiration.
Define: total lung capacity
Maximum volume of lungs
Which blood gas can be used to determine if a respiratory acidosis is acute or chronic?
Bicarbonate: in an acute problem, it will be high. In a chronic problem, it will be normal or near normal.
Which blood gas can be used to determine if acidosis is due to a respiratory problem or a metabolic problem?
CO2--in a respiratory problem, it will be high. In a metabolic problem, it will be normal.
Which is more affected by obstructive pulmonary disease, expiration or inspiration?
True or false: COPD consists of emphysema, chronic bronchitis, and asthma.
False; asthma is not considered part of COPD.
Asthma is associated with what type of hypersensitivity?
What gender, age, and race is more likely to develop asthma? Least likely?
Female, child, black are more likely to develop asthma. Male, adult, Hispanic are less likely to develop asthma.
True or false: having severe asthma as a child slightly increases your risk of developing COPD as an adult.
Falase; it greatly increases the risk (32X)
What are the signs and symptoms of asthma?
Chronic cough, wheezing and shortness of breath are the classic triad. Also possible are tightness in chest, sympathetic discharge, tachypnea, and, in severe cases, cyanosis of nail beds, confusion, agitation, and nasal flaring.
Briefly outline the pathophysiology of asthma.
Asthmatics have 10x more mast cells than normal, so initiating factors cause a huge response in inflammatory response. Histamines, prostaglandins, tryptase, and leukotrienes cause bronchospasm, mucosal edema, and hypersecretion of mucous. Eosinophils releases proteins toxic to epithelial cells, which undergo metaplasia and become goblet cells and secrete more mucous. Proteins and collagens deposit in basement membranes, which thickens walls and narrows airways. Smooth muscle undergoes hyperplasia and has less beta receptors, which leads to increased bronchoconstriction.
What tests are used to diagnose asthma?
Spirometry with postbronchodilator response, pulse oximetry if acute, chest radiograph, and exercise spirometry.
Asthma can be categorized based on frequency of symptoms, lung function tests (FEV1), and peak flow variability. What are the severity classes of asthma?
Intermittent, mild persistent, moderate persistent, and severe persistent.
What medications can be used for treatment of asthma?
Anti-inflammatory meds (steroids, LT inhibitors, mast cell stabilizers, monoclonal antibodies), adrenergic agonists (to reduce bronchospasm, mucous production, and mast cell degranulation), anticholinergics (prevent smooth muscle contraction), glucocorticoids (decrease inflammatory response), and monoclonal antibodies (decreases inflammatory response by binding with IgE).
Which medications are the agents of choice to relieve bronchospasm?
Adrenergic agonists (beta 2 specifically).
Which short acting bronchodilator is the most commonly used?
What is the advantage of inhalation powders over typical inhalers?
You don't have to have "hand-breath" coordination.
Which adverse effect of adrenergic bronchodilators is paradoxical?
Bronchospasm can occur with repeated use due to sensitization (your body needs more of the drug to get the same result).
True or false: anticholinergics for asthma treatment are off-label.
Anticholinergics prevent contraction of airway smooth muscle and are inhaled. Their onset is 3-4 weeks and they are typically less effective than beta 2 agonists.
What are possible side effects of anticholinergics?
Blurry vision, dry mouth, HA, dizziness, cough, mydriasis, conjunctival hyperemia, angle closure glaucoma.
Which class of medication is first option when treating moderate to severe asthma?
Inhaled glucocorticoids, due to their ability to decrease remodeling. They can be either aerosol or powdered.
What are the most common adverse effects of glucocorticoids? Which of these effects are less likely with inhaled glucocorticoids?
Osteoporosis, impaired wound healing, increased risk of infection, HTN, edema, ulcers, psychoses, Cushing-like syndrome, oral candidiasis. Decreased growth in children, glaucoma, cataracts, and increased risk of DM are less likely in inhaled vs. oral glucocorticoids.
Inhaled glucocorticoids should be used with caution in patients with what conditions?
Parasitic infection, active or inactive TB, ocular herpes simplex, or increased IOP.
Leukotriene inhibitors are not used for immediate bronchodilation and are taken orally. Their most concerning side effect is impact on liver function, though they can cause HA, fever, sore throat, sinus infection, and SJS.
Which medication for asthma is useful in children and pregnant women, and why?
Cromolyn is a mast cell stabilizer that is used for prophylaxis and is poorly absorbed, leading to few side effects.
Which medication for asthma is given as a subcutaneous injection? How does it work?
Omalizumab is a monoclonal antibody that binds to IgE and decreases its action. It decreases attacks experienced by patients, but has a risk of anaphylaxis.
What does alair bronchial thermoplasty involve?
A catheter is worked into the airways, which are heated to decrease their thickness and hyperresponsiveness.
What common medication should be avoided in asthmatics?
Aspirin; it blocks the prostaglandin side of the arachidonic acid metabolism pathway, shunting products toward the leukotriene side. Attacks can be triggered by aspirin (aspirin exacerbated respiratory disease (AERD).
What is the most common first symptom of COPD?
Dyspnea on exertion.
What is the #1 cause of COPD in the U.S.?
How is the severity of COPD evaluated?
Questionnaires and spirometry/FEV1 tests.
True or false: emphysema and chronic bronchitis both start with narrowing and loss of small airways.
True; they eventually have much different results.
Emphysema is characterized by the formation of bullae. What are bullae, and how do they form?
They are large spaces where there should be many small alveoli. Repeated and prolonged inflammation causes release of proteolytic enzymes (such as tryptase) that digests the alveolar septal walls.
What is the most common cause of the release of proteolytic enzymes in emphysema?
Why does less gas exchange occur in the lungs with emphysema?
There is less surface area for the exchange (alveoli are lost).
What is pneumothorax?
Air escaping into the thoracic cavity; this can occur in emphysema due to the bullae, which have weak walls.
If you could choose two words to describe the typical emphysema patient, what would they be? What do these two words imply about the condition?
Pink puffer; pink implies they have enough oxygen, and puffer refers to their tachypnea, which helps keep the airways from collapsing.
If a patient with severe emphysema were to sit in your waiting room, how might he position himself?
This would be a thin patient that might breathe with pursed lips (helps increase pressure to keep airways from collapsing), and they might put their hands on their legs and lean forward slightly ("tripod") to get help from the accessory muscles for respiration.
In order for chronic bronchitis to be diagnosed, what must a patient have experienced?
Persistent, productive cough on most days for at least 3 consecutive months in two consecutive years.
What clinical manifestations can occur in a patient with chronic bronchitis, apart from the cough?
Wheezing, crackles, tachycardia, and polycythemia.
Chronic bronchitis and emphysema both start the same way, with inflammation. What remodeling occurs in chronic bronchitis that makes it different from emphysema?
The mucous glands in the airways undergo hypertrophy and hypersecrete mucous.
If you could choose two words to describe the typical chronic bronchitis patient, what would they be? What do these two words imply about the condition?
Blue bloater--blue due to lack of oxygen, bloater because they don't have enough oxygen, so their physical activity is limited (also bloater due to edema from right sided heart failure).
If a patient with severe chronic bronchitis were to be in your waiting room, how might he look?
Obese, large chest, chronic coughing, and cyanotic/happy (due to CO2 narcosis).
What ocular effects might a patient with chronic bronchitis experience?
Decreased (night) VA, decreased color vision, decreased retinal function, swollen ONH, transient visual obscurations.
What are the five "A's" of smoking cessation?
As a doctor, you need to
-Ask patient about tobacco use
-Advise them to quit
-Assess their readiness to quit
-Assist them to set goals and get help
-Arrange a follow up
Medications for COPD are pretty similar to asthma. What are a few key differences?
Anticholinergics are FDA approved for COPD (they aren't for asthma), glucocorticoids are most useful during exacerbations and not as a maintenance med (as with asthma), and aspirin is okay to use because it decreases the platelet count (there is an increased risk of clotting in COPD).
What are a few classes of medications used for COPD that are not used for asthma?
Phosphodiesterase inhibitors, aspirin, and antibiotics (due to increased risk of infection).
True or false: patients with COPD should get their vaccinations
True; flu vaccine in particular has been shown to reduce morbidity and mortality.
What non-pharmaceutical options are available for a patient with emphysema?
Bullectomy (removal of bullae)/volume reduction surgery to reduce the pressure on healthy lung tissue; bronchoscopy (metal coils inserted which compress unhealthy tissue).
What non-pharmaceutical options are available for a patient with chronic bronchitis?
Respiratory dialysis with the Hemolung respiratory assist system.
Which obstructive pulmonary disease is the most lethal genetic disease affecting Caucasians? What is its inheritance trait?
Cystic fibrosis. It is autosomal recessive, so there are a lot of carriers (1/30 Caucasians).
The mutations that cause cystic fibrosis affect what type of ion channel? How does this affect the airways?
Chloride. If it can't leave cells, sodium can't leave cells, and water is pulled into the cells. This causes the viscosity of the mucous in the airways to increase. This causes obstruction of the airways and sets the stage for infection from even the normal lung flora. Persistent infection and inflammation causes damage to airway walls and destroys small airways.
Sweat chloride tests and genetic testing may need to be done if the cystic fibrosis newborn screening test comes up with uncertain results.
What is the most common cause of death for patients with cystic fibrosis?
Pulmonary failure secondary to infection.
Besides pulmonary and ocular, what other symptoms may a patient cystic fibrosis experience?
Poor digestion of fats (blocked pancreas ducts), poor absorption of proteins and carbs, infertility, cirrhosis, sleep apnea.
What ocular symptoms might a patient with cystic fibrosis have?
Aqueous deficient dry eye, reduced endothelial density, increased corneal thickness, PSC cataract, reduced contrast sensitivity, diabetic reinopathy, decreased macular pigmentation, xerophthalmia.
What techniques or treatments can be used to help clear the airways of a patient with cystic fibrosis?
Percussion/postural drainage, dornase alpha (makes sputum less viscous), hypertonic saline (to draw water out of cells, decrease viscosity of mucous).
What class of medications are the single most important factor for increased lifespan of a patient with cystic fibrosis?
Inhaled antibiotics such as tobramycin (TOBI).
Treatment for specific cystic fibrosis mutations exists. Which two treatments were discussed in class, and what is their mechanism of action? What percentage of the cystic fibrosis population does each treatment reach?
Ivacaftor helps keep chloride channels open, but by itself is good for only 5% of the cystic fibrosis population.
Adding lumacaftor (moves chloride channels) to ivacaftor (keeps channels open) increases the percentage to 25% of the cystic fibrosis population.
What is the definition of apnea?
Complete cessation of respiration for at least 10 seconds.
Central sleep apnea is not considered an obstructive respiratory condition. What is a common cause of central sleep apnea? Briefly describe the mechanism of the apnea.
Heart failure is a common cause of central sleep apnea. Cheyne-Stokes respiration occurs: the central receptors will sense a decrease in the levels of blood oxygen and trigger an increase in respiration rate. The newly oxygenated blood takes time to get to the receptors, by which point the patient is experiencing hyperpnea and the blood is over-oxygenated. The receptors then tell the respiration rate to slow, leading to eventual apnea through the same type of process.
True or false: sleep apnea is found in up to 1/4 of individuals over 20 years of age
False; it is found in up to 1/4 of males over 20 years of age.
Besides the symptoms of excessive daytime sleepiness and being tired upon awakening, what other symptoms might a patient with sleep apnea have?
Loud snoring, morning headaches, and cognitive impairment.
Sleep apnea is due to the collapse of the upper airway during sleep. The patient will thrash, snort, and gasp in their sleep and reopen the airway. What factors contribute to this condition?
Obesity, thick necks, small/receded jaw, increased soft palate and tongue, heavy drinking, history of asthma.
What tests are used to diagnose sleep apnea? Which is the gold standard?
Sleepiness questionnaires and nocturnal polysomnography (measure eye movements, chest wall, electromyogram, electroencephalogram, electrocardiogram, oximetry, and nasal/oral air flow during sleep. Nocturnal polysomnography is the gold standard.
Some medical conditions are associated with sleep apnea. Which are they?
HTN, obesity, MS, DM, CV disease.
Some medical conditions have an increased incidence in a patient with sleep apnea. Which are they?
Cognitive decline, emotional problems, impotence, oxteoporosis, glaucoma (especially normal tension), anterior ischemic optic neuropathy.
What non-surgical treatment options are there for a patient with sleep apnea?
Weight loss, tongue retaining devices, oral mandibular advancement devices, tennis balls on pajamas, anti-inflammatory meds for kids, constant positive airway pressure (CPAP), oropharyngeal exercises.
What surgical treatment options are there for a patient with sleep apnea?
Tonsillectomy (for kids), uvulopalatopharyngoplasty (UPPP; upper airway surgery), Inspire Device ("pacemaker" to move tongue forward), jaw surgery, trachestomy
What two main categories of restrictive lung diseases were discussed in class?
Infiltrative (pneumonconiosis, collagen vascular diseases, and sasrcoidosis) and chest wall abnormalities (kyphoscoliosis, obesity, and respiratory muscle fatigue).
Briefly outline the pathophysiology of infiltrative lung disease.
Something infiltrates the lungs, causing diffuse injury and inflammation. The alveoli become scarred and the septa thicken and stiffen. The reduced stretch of the lungs makes it harder to breathe, and gas exchange is decreased due to thicker walls.
Pneumoconiosis is an umbrella term for which conditions discussed in class?
Asbestosis, black lung, and silicosis.
What causes pneumoconiosis? How do you treat it?
Inhalation of inorganic dust. No treatment except remove from the offending environment.
True or false: the biggest concern of asbestosis is outside of the U.S.
False; biggest concern is in the U.S.
What two factors are important in the development of fibrosis due to asbestosis?
Dose of asbestos and fiber dimension (shape, length, diameter).
True or false: asbestosis increases the risk for bronchogenic carcinoma
True. Malignanat mesothelioma of the pleura and peritoneum is also associated with asbestos exposure.
Which condition is the most common occupational disease in the world?
Which age range is most common to develop sarcoidosis? Which gender? Which ethnic group?
20-40 years, women, African American
Sarcoidosis is characterized by the development of _____________ throughout the body.
Sarcoidosis is a multisystem disorder. Which three system are most affected?
Pulmonary (95%), dermatologic, and ocular (20%).
What respiratory symptoms may be found in a patient with sarcoidosis?
Dry cough and dyspnea most commonly. Paratracheal and hilar adenopathy are also possible, as are infiltrates and fibrosis.
What ocular symptoms may be found in a patient with sarcoidosis?
Anterior uveitis most commonly. Can also have granulomas, conjunctivitis, lacrimal gland inflammation, retinal vasculitis, ONH edema, and cranial neuropathies.
How would you evaluate a patient for sarcoidosis?
Chest x-ray, pulmonary function tests; lab tests for ACE (released by pulmonary granulomas), creatnine, calcium, and liver enzymes; TB test (to rule it out); and Kveim test.
How would sarcoidosis be diagnosed?
Three elements are required for diagnosis: consistent clinic history and x-ray; exclusion of other disease; and biopsy for granuloma.
What sort of prognosis might you expect for a patient with sarcoidosis?
Rule of 1/3's:
33% spontaneous remission
33% remain stable
33% have progression (with 10% developing severe pulmonary fibrosis)
How would you treat symptomatic sarcoidosis?
Anti inflammatory meds (oral corticosteroids, steroid inhalers); immune modulating meds for severe cases (methotrexate, cyclosporine, hydroxychloroquine, azathioprine)
What is an optometrist's rule in the care of a patient with sarcoidosis?
The patient needs to have a baseline eye exam within the 1st year (including SLEx, DFE, GAT, and 10-2 VF). They need to have an annual exam thereafter (sooner if visual disturbance). And after 5 years of hydroxychloroquine use, they need to have a DFE and 10-2 VF and if possible a SD-OCT (spectral domain OCT) or mfERG (multifocal electroretinography), or FAF (fluorescein autofluorescence).
How does kyphoscoliosis affect respiration?
The spine is curved, reducing lung volumes and increasing the stiffness of the chest wall. This allows the alveoli to collapse. All of these increase the work of breathing. Respiratory failure due to elevated CO2 eventually occurs.
How does obesity affect respiration?
The diaphragm and chest wall are mechanically compressed, leading to decreased ventilation of lung bases and hypoxemia, especially when lying down.
In the early 1900s, 1 in 5 people in the U.S. had active TB, and 1 in 7 people in the U.S. died from active TB. Has the incidence of TB increased or decreased since then?
Overall, decreased, but there was a resurgence in 1986.
What happened in 1986 in relation to TB? What caused this to happen?
There was a resurgence of TB incidence. It was due to the HIV epidemic, immigration of individuals from TB prevalent countries, rise of multidrug-resistant mycobacterial organisms, and decline of TB control programs.
True or false: TB kills more people worldwide than AIDS.
False; but TB does come in second after AIDS.
Which individuals are at higher risk for contracting TB?
-Close contact of patients suspected of having TB
-Health care workers serving high risk patients
-Residents/employees of long-term care facilities, jails, homeless shelters, mycobateriology labs
-Recent immigrants from high TB prevalence countries
-Injectable drug users
-Patients with chronic medical conditions
-Children under 4 years old
True or false: the tuberculin skin test is injected perpendicular to the long axis of the arm, and measured parallel to the long axis of the arm.
False; it is injected parallel to the long axis and measured perpendicular to the long axis.
TST results are made by measuring the induration of the resulting reaction, not the redness. In which individuals would an induration of 5 mm be considered posittive?
-Close contact with an active TB or recently exposed individual
-Chest x-rays showing fibrosis
TST results are made by measuring the induration of the resulting reaction, not the redness. In which individuals would an induration of 10 mm be considered posittive?
Any high risk individual who doesn't meet the 5mm criteria (health care worker)
TST results are made by measuring the induration of the resulting reaction, not the redness. In which individuals would an induration of 15 mm be considered posittive?
For whom does the CDC recommend 2 step testing for initial TB screening?
For anybody needing to have periodic testing.
What two conditions qualify as seroconversion, in terms of a TST?
A change from a negative to a positive reaction, or an increase of 10 mm or more in size.
QuantiFERON is an interferon gamma release assay (IGRA) that is an alternative to the TST. What are the benefits of IGRAs over TST?
Blood is drawn, so only one patient visit.
Results available in 24 hours.
Test does not cause booster phenomenon.
BCG vacinnation doesn't cause a false positive.
What percentage of non-HIV+ patients with TB have ocular signs? What about HIV+ patients?
1-2% of non-HIV+ patients, 18% of HIV+ patients. The ocular symptoms can be in the anterior segment or the posterior segment, and is basically a lot of inflammation (lots of "itis"es).
Which test is the gold standard to differentiate active vs latent TB?
Sputum evaluation; use an acid fast stain and perform nucleic acid amplification.
In drug sensitivity testing for TB, what is the advantage of gene based vs. culture based?
Gene based is rapid and accurate; culture based is slow and accurate. Gene based is expensive, though, whereas culture based is inexpensive.
What are the goals of TB treatment?
Eradication of the infection
Prevention of drug resistance
Prevention of transmission
Prevention of reactivation
What are the two latent TB treatment methods discussed in class? Which of these is the preferred treatment for HIV+ and young children?
Isoniazid (INH) 5 mg/kg po qd for 9 months.
ING 15 mg/kg rounded up to nearest 50 or 100 mg plus rifapentine (300-900 mg based on weight) 12 once weekly doses.
The INH only treatment is the preferred for HIV+ and young children.
What are the adverse effects of INH?
Chiefly hepatotoxicity; also anemia, GI symptoms, peripheral neuropathy, SEIs, optic neuritis, VF defects, EOM paresis.
What are the adverse effects of rifapentine?
Reddened secretions, N&V, fever.
Which vitamin supplement would you add to either of the treatment for latent TB?
There are a few different treatments for active TB. Which one was discussed in class?
INH + rifampin + pyrazinamide + ethambutol + pyridoxine qd for 8 weeks, followed by INH + rifampin + pyridoxine 2x per week for another 18 weeks with direct observation therapy.
What are the adverse effects of ethambutol?
Most importantly is optic neuritis; also macular edema and pigment changes.
How often should patients being treated for TB have eye exams? What should these eye exams include?
Monthly; should include VAs, EOMs, Amsler grid, VF, pupil exam, R/G color vision, SLEx, DFE.
If you believe you've been exposed to TB, what testing should you seek?
If you've had a previous negative TST within the last year, test in 8 weeks. If you haven't had a TST within the last year, get a TST immediately and then again in a few weeks.
Histoplasmosis is a fungal infection. For adults, the primary site of involvement is the lungs. For children, it's the liver.
True or false: histoplasmosis is extremely contagious from person to person.
False; it cannot be passed from one human to another.
About how many people in the U.S. are infected with histoplasmosis? How many new infections are there each year?
50 million currently infected; 200,000 new cases each year.
In which areas of the U.S. is histoplasmosis most commonly found?
Ohio and Mississippi river valleys (60-90% exposure)
Briefly outline the disease process of histoplasmosis.
Spores are inhaled and fungi proliferate in the lungs. PMNs and macrophages infiltrate the lungs and phagocytotize the fungi but don't kill it. They carry it throughout the body. An immune resopnse develops, leading to granuloma formation, necrosis, and fibrotic encapsulation, which can later calcify (histoplasmoma).
There are four categories of histoplasmosis. Which is uncommonly diagnosed and found usually in infants and children? How is the prognosis?
Primary acute. Resolves to the benign form in 1-3 months without treatment
There are four categories of histoplasmosis. Which is the most common form? Which syndrome might we as optometrists identify in these patients?
Benign is the most common. We could identify presumed ocular histoplasmosis syndrome (POHS). This syndrome involves circumpapillary choroiditis, atrophic chorioretinal scars (histo spots), and exudative maculopathy. Choroidal neovascularization can occur.
There are four categories of histoplasmosis. Which is usually found in the very young, very old, or immunosuppressed patients? What symptoms can occur in this category? What is the prognosis for a patient in this category?
Disseminated histoplasmosis. Poor T-cell immune response has allowed the fungi to disseminate (spread). Many symptoms are nonspecific (fever, chills, cough, etc.). Hypersplenism can occur and pulmonary infiltrates may be seen on x-rays. Adrenal glands will be involved and may yield Addison disease. If not treated, up to 80% mortality within 4-10 months. If treated, this drops to less than 25%.
There are four categories of histoplasmosis. Which occurs when already-diseased lung tissue (COPD, emphysema, etc.) is infected by the fungi? What symptoms can occur in this category?
Chronic pulmonary. Histoplasmomas can form, and bronchiectasia can occur (small airway collapse). Chest pain can also occur in this category. Could resolve in 1-3 months or be a chronic condition.
Although a good history and x-ray exams can help with identifying histoplasmosis, what test is definitive? What other tests are available?
Isolation by culturing (which takes several weeks) is the definitive test.
Can also use antigen detection (enzyme immunoassay through urine* or serum) and antibody tests (only proves exposure).
How would you treat primary acute and benign histoplasmosis?
How would you treat disseminated and chronic pulmonary histoplasmosis?
Anti-fungals for 3m-1 year
-IV amphotericin B
-To treat Addison and decrease damage from inflammation
Which patients with histoplasmosis may find themselves on anti-fungals for life?
What is the mechanism of action of the anti-fungal medications for histoplasmosis? What are the important side effects of these drugs?
Drugs bind to cell membrane and disrupts metabolic activity, but can be toxic to human cells. Important toxic effects are renal and liver toxicity.