Respiratory Flashcards
What is the most common cause of lobar pneumonia in adults?
Streptococcus pneumoniae
Unvaccinated child with paroxysmal cough and inspiratory whoop - diagnosis?
Whooping cough caused by bordetella pertussis
Why does bordetella cause hypoglycemia?
Toxin activates islets of Langerhans
What is the most common cancer arising from scarred lung?
Adenocarcinoma
What are tumors that arise peripherally and cause coin lesions?
Adenocarcinoma, bronchioloalveolar carcinoma, large cell carcinoma
What acid-base disturbance does acute salicylate poisoning lead to?
Respiratory alkalosis
How does hyperventilation affect cerebral blood flow and cerebral vascular resistance?
Decreased cerebral blood flow
Increased cerebral vascular resistance
Because decreased levels of CO2 cause cerebral vasoconstriction
What would a biopsy of tissue infected with Histoplasma show?
2-5 micrometer yeast with a thin cell wall but no real capsule
What should you think of if you see an immunosuppressed patient with owl’s eye inclusion bodies in cells?
CMV
What lab values will change when giving supplemental oxygen to a patient with pulmonary diseaese?
Increase PAO2, PaO2, A-a gradient
Will NOT change lung diffusion capacity
Why does the abdominal wall move inward on inspiration with a diaphragmatic injury?
Contraction of the intercostal muscles during inspiration results in the diaphragm being sucked upward (negative pressure in the pleural space) and the abdominal wall being sucked inward
What happens to pulmonary vessels at high altitude?
Vasoconstriction (decreased diameter) due to hypoxia
What PO2 level decreases in anemic patients?
Mixed venous PO2
What should be at the top of your differential for a unilateral pleural effusion?
Bacterial infection
What respiratory infection should you suspect among infants in the winter months?
RSV
How do you treat an RSV infection?
Palivizumab - antibody directed against the fusion protein of RSV
What antibiotic inhibits translocation of the growing peptide chain along the mRNA?
Macrolide
Why are asthmatic patients at increased risk of oral candidiasis?
Use of inhaled corticosteroids
Presentation: bilateral hilar adenopathy, history of nonspecific joint inflammation, cutaneous symptoms
Diagnosis?
Sarcoidosis
How is CFTR regulated?
Gated by ATP hydrolysis and involves regulation by protein kinase A phosphorylation
Presentation: history of asthma, sudden onset shortness of breath, altered breath sounds
What should you suspect?
Pneumothorax
How does pneumothorax look on X ray?
Radiolucency
What is a chylous effusion?
Exudative effusions (pleural fluid protein to serum protein > 0.5, pleural to serum LDH > 0.6) with high lipid content, most commonly related to trauma and malignancy
How does the vagus nerve affect the lungs?
Bronchoconstriction leading to increased airway resistance and work of breathing
What fungus, at body temperature, is a spherule filled with endospores?
Coccidioides
What is the mechanism of action of aminoglycosides?
Inhibit the initiation of protein synthesis by binding to and distorting the structure of the prokaryotic 30s ribosomal subunit
What medications target synthesis of the fungal cell wall?
Echinocandins (e.g. caspofungin and micafungin) inhibit synthesis of the polysaccharide glucan, an essential component of the fungal cell wall
What happens to diffusing capacity (DLCO) in emphysema patients?
Decreases
What is Cheyne Stokes respiration?
Cyclic breathing in which apnea is followed by gradually increasing tidal volumes and then decreasing tidal volumes until the next apneic period
When is rifampin used as monotherapy?
For prophylaxis against Neisseria meningitidis
Presentation: Recurrent sinopulmonary and GI tract infections, anaphylactic response to transfused blood products
Diagnosis?
IgA deficiency (most common primary immune deficiency)
Which TB drug can adversely affect the eye?
Ethambutol can cause optic neuritis (presents in conjunction with decreased visual acuity, central scotoma, color blindness)
How does N-acetylcysteine help CF patients?
Mucolytic agent - it cleaves the disulfide bonds within mucus glycoproteins (loosens thick sputum)
What are the most common bacterial infections (secondary pneumonia) that superimpose over influenza infection?
Strep pneumo > Staph > H. flu
What does it mean if mycobacterium can grow in parallel chains?
These are serpentine cords meaning the mycobacterium has cord factor meaning it is a virulent strain
Why is expiratory flow rate increased in restrictive lung disease?
Expiratory flow rate is increased due to decreased lung compliance (increased elastic recoil) and increased radial traction exerted on the conducting airways by the fibrotic lung
Which TB drug requires an acidic environment?
Pyrazinamide (works best within phagolysosomes)
If a patient has tracheal PO2 that does not match alveolar PO2, what is that indicative of?
Should equilibrate in normal conditions because O2 is a perfusion limited gas so in this case it means there’s poor perfusion
Where does the recurrent laryngeal nerve travel relative to the aorta?
Goes beneath the arch of the aorta (but above the pulmonary artery) through the aorticopulmonary window
How does sarcoidosis affect the elasticity of the lung?
Increases it (as do other restrictive lung diseases)
What acid-base disturbance does acute salicylate poisoning lead to?
Respiratory alkalosis
What is on your differential for an interstitial pneumonia that responds to macrolides?
Mycoplasma pneumoniae or legionella
If it didn’t respond to macrolides, you would think of viral etiologies
What responds more quickly to changes in PCO2 - peripheral or central chemoreceptors?
Peripheral
Assuming normal PO2 of 100 mm Hg, what would you expect in terms of oxygen bound to hemoglobin in a patient with 75% of normal hemoglobin (anemic)?
Arterial blood has 75% as much oxygen bound to hemoglobin because Hb is 100% saturated with oxygen at 100 mm Hg
How would you differentiate between histoplasmosis and blastomycosis on histology?
Histoplasmosis - tiny oval forms within macrophages
Blastomycosis - larger, round budding yeast forms in tissues
Is strep pneumo alpha, beta, or gamma hemolytic?
Alpha
What is the most common form of lung cancer?
Bronchogenic adenocarcinoma
Post influenza bacterial pneumonia with cavitary lesions - likely cause?
Staph
What antibiotic would be contraindicated in treating a patient for H. influenza if that patient was also on anticoagulants?
Macrolides because they inhibit CYP 450 and would potentiate the effects of warfarin
What is the mechanism of action of macrolides?
Bind to the P site of the 50s ribosomal subunit and interfere with bacterial protein synthesis
What acid base disturbance does heroin overdose lead to?
Acute respiratory acidosis from hypoventilation
How can you differentiate between SCID and DiGeorge?
DiGeorge is a type of SCID but in terms of picking an answer:
DiGeorge - look for classic findings like facial abnormalities, hypoparathyroidism, cardiac defects
SCID - more severe immune dysfunction
Why is someone with a seizure disorder at increased risk of lung abscess?
Aspiration of oropharyngeal contents (e.g. mouth flora like peptostreptococcus, fusobacterium)
What is the effect of ether (and other organic solvents) on viruses?
Can dissolve the lipid bilayer that makes up the outer viral envelope - leads to loss of infectivity
If a foreign body becomes lodged in the piriform recess, what nerve can it damage?
Internal laryngeal (branch of vagus that is involved in the cough reflex)
What bacteria is the most likely cause of pneumonia in a patient with GI symptoms, neurological symptoms, and recent exposure to contaminated water (e.g. cruise ships or hotels)?
Legionella pneumophila
What is the most common laboratory abnormality seen with Legionella?
Hyponatremia
Neutrophils fail to turn blue upon nitroblue tetrazolium exposure - what does this mean?
Chronic granulomatous disease - patients cannot reduce nitroblue tetrazolium because they have a genetic defect resulting in NADPH oxidase deficiency
What kind of organisms are neutrophils in chronic granulomatous disease bad at killing?
Not effective at killing catalase positive organisms
What vitamin deficiencies are associated with cystic fibrosis?
A, D, E, K
Because these are fat soluble vitamins and pancreatic insufficiency inhibits fat absorption
Lung abscess is a common complication of what disease?
Aspiration pneumonia
Histology: round yeast with doubly refractive walls and broad based budding?
Blastomyces
What do you worry about injuring above the clavicle and just lateral to the sternal manubrium?
Apex of the lung or the pleura (think pneumothorax)
What three cytokines help raise the ESR through a systemic inflammatory response?
IL-1, IL-6, TNF-alpha
Stimulate hepatic production of acute phase reactants like fibrinogen
What is another name for phosphatidylcholine?
Lecithin
Describe how lecithin vs. sphingomyelin levels in the amniotic fluid change during pregnancy.
Sphingomyelin - fairly constant
Lecithin - approximately equal to sphingomyelin until 3rd trimester and then shoots up
An L:S of 2:1 is a marker for healthy lung maturation
For an autosomal recessive disease, what is the chance that an unaffected individual with unaffected parents (but who are both carriers) with be a carrier for the disease?
2/3
What test is carbolfuchsin dye used for?
Acid fast
What does acid fast stain stain for?
Mycolic acid
What do we use to treat IL-12 deficient patients?
IFN-gamma (helps promote Th1 response which they have trouble doing without IL-12
What fungal infection can complicate asthma?
Aspergillus fumigatus
How can bronchioalveolar lavage fluid be used to diagnose sarcoidosis?
High CD4/CD8 ratio is diagnostic of sarcoidosis
What is pyridoxine?
Vitamin B6
What drug is pyridoxine related to?
Isoniazid
When is pulmonary vascular resistance lowest?
At functional residual capacity (after normal tidal volume)
Describe how airway frictional resistance changes as you move from the larger bronchi to the smaller ones. Where does it reach its maximum?
Most of the airway resistance comes from the first ten generations of bronchi (maximum at generations 2-5) vs. very little from the smallest ones
What is the typical mechanism of resistance against streptomycin?
Altered structure of bacterial ribosomal proteins because streptomycin (like other aminoglycosides) work by inactivating the 30s subunit
What do you need to know in order to PCR sequence a segment of DNA?
The sequence of the flanking regions
Why does chloride shift into erythrocytes in venous vs. arterial blood?
In venous blood, erythrocytes are carrying carbon dioxide which gets converted to H+ and bicarbonate from carbonic anhydrase. The bicarbonate diffuses out into the plasma and so chloride shifts into the RBC to maintain electroneutrality.
What is the primary virulence factor of strep pneumo?
Polysaccharide capsule that inhibits phagocytosis
What part of the respiratory system is particularly affected by chronic rejection in lung transplantation?
Small airways - bronchiolitis obliterans syndrome
Does small cell or squamous cell lung cancer stain positive for chromogranin?
Small cell
What would you expect as an acid-base disturbance from chronic exposure to high altitude?
Respiratory alkalosis (due to hyperventilation) with decreased bicarbonate as renal compensation
What cytokine is important for the formation of a granuloma?
IFN-gamma
What receptors can be pharmacologically targeted for asthma?
- Leukotrienes - LTC4, LTD4, LTE4
2. Acetylcholine
What does the pneumococcal vaccine contain?
Capsular polysaccharides
What causes the tissue damage that allows a lung abscess to form?
Lysosomal enzymes released from neutrophils and macrophages
Pain upon inspiration in the neck and shoulder region is coming from what nerve?
Referred pain from phrenic nerve (C3 - C5)
Likely due to irritation of the pleura
Which RNA polymerase synthesizes the vast majority of rRNA from within the nucleolus?
RNA polymerase I
Where is the most highly oxygenated blood in fetal circulation?
Umbilical vein which empties directly into the IVC via the ductus venosus
Why is the mucus dehydrated in CF?
CFTR isn’t working –> inhibits Cl secretion –> drives Na reabsorption –> dehydrates the mucus
Which antifungals bind ergosterol in the fungal cell membrane?
Polyenes (amphotericin B and nystatin)
What are the major toxicities of theophylline overdose?
Abdominal pain, vomiting, seizures
For a naked RNA virus to induce the host cell’s own machinery to synthesize proteins, does it have to be positive or negative?
Positive - meaning it is acting directly as mRNA
What is the difference between t-test and ANOVA?
T-test: compare the difference between the means of 2 groups
ANOVA (analysis of variance): compare the difference between the means of 2 or more groups
Aside from histamine, what other mast-cell specific enzyme is released in excess during anaphylaxis?
Tryptase
What is the intrapleural pressure at FRC?
-5 cm H2O
What is arterial PaCO2 a direct indicator of?
Alveolar ventilation
Is blastomyces or aspergillus more likely to cause chronic pneumonia in an immunocompetent host?
Blastomyces
What is cromolyn?
Mast cell stabilizing agent - inhibits mast cell degranulation
Nedocromil is another mast cell stabilizing agent
In a patient with lobar pneumonia, if the lung is pale but has fragments of RBCs, is it in red hepatization or gray hepatization?
Gray
Histology: well differentiated lung tumor with composed of tall, columnar cells that line the alveolar septa without evidence of vascular or stromal invasion
Diagnosis?
Bronchioloalveolar carcinoma
Why is capillary wedge pressure normal in acute respiratory distress syndrome?
One of the minor diagnostic criteria = absence of cardiogenic pulmonary edema
How does the body get rid of strep pneumo?
Bacterial clearance via spleen (encapsulated organism)
How does the influenza vaccine work?
Composed of inactivated viral components that increases host circulating antibodies against hemagglutinin so that the virus has trouble entering cells
What kind of epithelium is found in the oropharynx, laryngopharynx, anterior epiglottis, upper half of the posterior epiglottis, and vocal folds?
Stratified squamous epithelium
What TB drug must be processed by mycobacterial catalase-peroxidase for the drug to be activated within the bacteria?
Isoniazid
What is the difference between central vs. peripheral chemoreceptors and what they respond to?
Central - senses CO2 levels to regulate respiratory drive
Peripheral - senses O2 levels in severe cases of hypoxia
What is the most common cause of acute epiglottitis and why do we not see it much anymore?
H influenza type B
Decreased because of vaccine
Normal PaO2 and % sat, but low O2 content.
What is this suggestive of?
Anemia (e.g. chronic blood loss)
Is strep pneumo bile sensitive or bile resistant?
Bile sensitive
What is another way to describe aspergilloma?
Colonizing aspergillosis
What is a common cause of bilateral absence of vas deferens?
Cystic fibrosis
What category of drugs will only reverse vagally-mediated bronchoconstriction?
Antimuscarinics (e.g. ipratropium)
What happens during the first week of exposure with TB?
Intracellular bacterial proliferation
What are hamartomas composed of?
Disorganized cartilage, fibrous and adipose tissue
What is the Reid index?
Ratio of the thickness of the mucous gland layer to thickness of the bronchial wall between respiratory epithelium and cartilage
What can be used as prophylaxis in patients at risk for MAC?
Weekly azithromycin
What is mucicarmine stain used for?
Stains the polysaccharide capsule of cryptococcus neoformans
Which viruses exhibit a form of replication in which they produce a polyprotein product that is later cleaved by a viral protease to produce functional, individual proteins?
Single-stranded, positive sense, linear, non-segmented RNA viruses (e.g. Picornaviruses like echovirus)
How far down (rib number) do the lungs go on the mid axillary line?
Rib 9
What is the best lab value for helping to determine the cause of metabolic alkalosis?
Urinary Cl - it will be decreased if the cause is loss of hydrogen ions from the body (e.g. vomiting) and increased if the cause is diuretics/primary hyperaldosteronism
Describe what happens to pH, PaO2, PaCO2, plasma HCO3 in the setting of pulmonary embolism.
Hypoxemia leading to hyperventilation which leads to increased pH (respiratory alkalosis), decreased PaCO2, decreased PaO2 (hypoxemia), and decreased HCO3 (to account for the loss of H+ to increase the pH)
Oral thrush, interstitial pneumonia, and severe lymphopenia during the first year of life suggest vertical transmission of what?
HIV
How can vertical transmission of HIV be reduced?
Maternal prophylaxis during pregnancy with the nucleoside analog zidovudine (ZDV, AZT) - a retroviral reverse transcriptase inhibitor
Why are patients with silicosis at increased risk of TB infection?
Disruption of macrophage phagolysosomes by internalized silica particles
What happens if a patient has a defect in antibody class switching?
Hyper-IgM
What would you give in terms of medication to an alcoholic with a lung abscess?
Clindamycin - covers both the gram positive strep pneumo pneumonia as well as anaerobes that likely cause the abscess from aspiration
What medication would you consider giving to a child/infant with severe RSV infection?
Ribavirin
What does amphotericin B bind to?
Ergosterol in fungal cell membranes but can also bind to cholesterol in human cell membranes (causing most of its toxicities)
What drug can assist patients with cessation of tobacco use by reducing withdrawal cravings and attenuating the rewarding effects of nicotine?
Varenicline - partial agonist of nicotinic acetylcholine receptors
Why is the pO2 in the left atrium lower than that in the pulmonary capillaries?
Deoxygenated blood from the bronchial arteries mixes with oxygenated blood in the pulmonary veins
What vaccines use diphtheria toxoid as their protein carrier?
- Strep pneumo
- Neisseria meningitidis
- H flu
What is a common cause for legionella outbreak in a hospital setting?
Colonization of the hospital water system (e.g. humidification system, air conditioning, water-based cooling system)
What protects bacteria from osmotic stress?
Peptidoglycan wall
What 3 class of antibiotics disrupts the bacterial peptidoglycan wall?
- Penicillins
- Cephalosporins
- Vancomycin
Histology: Large spherule filled with endospores?
Coccidioides
Deletions or additions of a number of base pairs not in a multiple of 3 indicates what kind of mutation?
Frameshift
Antibodies to polyribitol ribose phosphate (PRP) carry protection against?
H flu type B (PRP is in its capsule)
What is the difference between TB and sarcoid on biopsy?
TB - caseating granulomas, acid-fast bacilli
Sarcoidosis - noncaseating granulomas
What are the 2 most common causes of SVC syndrome?
- Lung cancer
2. non-Hodgkin lymphoma
The green discoloration of pus or sputum during bacterial infections is associated with the release of what?
Myeloperoxidase from neutrophil azurophilic granules - myeloperoxidase is a heme containing pigmented molecule
Pneumoconiosis with egg-shell calcifications of hilar nodes and birefringent particles surrounded by dense collagen fibers?
Silicosis
Why does mycoplasma pneumoniae infection cause anemia?
Cold agglutinins - the body lyses some of its own RBC’s as the antibodies against mycoplasma share some of the antigens
What component of inflammatory exudate is most important for inducing rapid neutrophil locomotion?
LTB4
What are the 4 major causes of hypoxemia (low PaO2)?
- Alveolar hypoventilation
- V/Q mismatch
- Diffusion impairment
- Right to left shunting
How can you distinguish alveolar hypoventilation from the other causes of hypoxemia?
Hypoventilation shows normal A-a gradient
