Resp. path Flashcards
What is the main enzyme implicated in emphysema?
Neutrophilic Elastase
Define emphysema
COPD w/ permanently enlarged air sacs distal to terminal bronchioles w/ destruction of their walls and w/o obvious fibrosis
5 morphological subtypes of emphysema
- centrilobular - esp. w/ cigarettes
- panlobular / panacinar - a1-antitrypsin and end-stage centrilobular
- paraseptal - assoc. w/ pulmonary fibrosis. may -> spontaneous pneumothorax
- irregular - associated w/ pulmonary scars
- interstitial - subcutaneous. due to trauma or elevated intraalveolar pressure
What type of emphysema is cigarette smoking usually associated with?
Centrilobular
Anthracosis often present
What part of respiratory tree is involved in centrilobular emphysema?
Primarily respiratory bronchioles due to high conc. of inhaled irritants
More prominant in upper lung fields
Chronic Bronchitis Definition
Productive cough w/o discernible cause for at least 3 months in 2 consecutive years
Reid index
Ratio of thickness of mucous glands to total thickness of airway wall.
Elevated in chronic bronchitis
status asthmaticus
most severe subtype of asthma - prolonged interval of continual symptoms, unresponsive to treatment
May be life-threatening
Common effector pathway of asthma
Stimulus in susceptible host -> release of inflammatory mediators -> increased vascular permeability, edema, neural and cytokine mediated bronchoconstriction, mucus hypersecretion, chemotaxis of additional inflamm. cells -> amplification
Major chemical mediators of acute phase of asthma
Histamine LTC4, D4, E4 PGD2 - mucus prod PAF Parasympathetic neural reflexes
What happens in late phase of asthma?
Infiltration of white cells (esp. eosinophils) in response to locally released chemotactic factors
LTB4, eotactin
Prolongation and augmentation of disease process
2 common drugs that can contribute to asthma
aspirin: decreased prostaglandin production and relative increase in leukotriene
B-antagonists: may precipitate bronchospasm
What respiratory disease is assoc. w/ mucus plugs?
asthma
Curschmann Spirals and Charcot-Leyden Crystals - what are they and what are they associated with?
Curschmann Spirals: mucoid swirls of epithelial cells
Charcot-Leyden Crystals: extruded eosinophil granules - needle-like crystals
What is bronchiectasis
Permanent airway dilation due to recurrent infections w/ necrosis
Atelactasis neonatorum
Incomplete expansion of lungs at birth
What happens to the mediastinum in obstructive atelactasis?
Mediastinal shift toward atelactic lung
What happens to the mediastinum in compression atelactasis?
Mediastinal shift away from atelactic lung
Effects of alpha, B1, and B2 agonists
alpha: vasoconstriction and vasopressor -> decongestion
B1: increased myocardial conductivity, increased HR and contractile force
B2: relax bronchial sm. muscle, inhibit inflamm. mediator release, stimulate mucocilliary clearance
What receptors do epinepherine, ephederine, and isoproterenol work at?
epinepherine: B1, B2, alpha
ephedrine: B1, B2, alpha
isoproterenol: B1, B2
How do selective B2 agonists work?
increase AC -> increased cAMP -> sm. muscle relaxation
3 short acting B2 agonists
Albuterol
Levalbuterol
Pirbuterol
What is the difference between albuterol and levalbuterol?
Albuterol is a racemix mix of R and S enantiomers
Levalbuterol is only R (active)
considered equal, but levalbuterol is expensive.
What is the difference between salmeterol and formoterol?
Both last 12+ hrs
Formoterol is a full B2 agonist and has faster onset
Salmeterol is a partial B2 agonist
2 long acting B2 agonists available in 1x daily dosing?
Indacaterol
Vilanterol
Both available as DPI
What genetic factor has been associated with increased susceptibility to B2 agonist tolerance?
Gly16 polymorphism of B2 receptor.
-> reduced responsiveness to agonists
What is the recommendation regarding use of long acting B2 agonists in treating asthma?
Black box warning: should not be used as monotherapy. increased risk of death
What is the primary mechanism of action of anticholinergics in treatment of obstructive respiratory disease?
Reduction of intrinsic vagal tone
In what patient population is ipratropium contraindicated?
Those w/ soy lecithin or peanut allergy.
Propellant contains lecithin
2 long acting anticholinergic drugs for control of COPD and sites of action.
Tiotropium blocks M1-M3 receptors, but dissociates from M2 quickly. M1 and 3: long duration of action
Aclidinium blocks M1-M5. pharmacological action at M3
Zileuton
Blocks 5-LOX preventing leukotriene production.
Used in chronic maintenance of asthma
Montelukast and Zafirlukast
Long acting controlers of COPD
Selective and competitive inhibition of Cys LT1 receptor -> prevention of production of LTD4 and E4
What would be a good medication for chronic management of asthma for a child under 5?
Montelukast
No drug interactions
Chewable tablet / granule form
Indicated for children >1
What is lipocortin?
Induced by corticosteroids
Inhibits PLP A2 -> decreased production of prostaglandins and leukotrienes
What is the time of onset for inhaled corticosteroids?
From days up to 2 weeks
Adverse reactions to inhaled corticosteroids?
Cough, dysphonia Oral Thrush (rinse mouth after using inhaler) Adrenal suppression, osteoporosis, skin thinning (high doses) Decreased growth velocity in children at low doses - may be transient.
What is the mechanism of methylxanthines?
Nonselective inhibition of phosphodiesterase
Increased cAMP -> smooth muscle relaxation
Effects intercellular Calcium
Mild anti-inflammatory
2 methylxanthine drugs
Theophilline
Aminophilline
Narrow therapeutic window!
What is the main concern w/ theophilline use and what factors must be considered?
Narrow therapeutic window (3rd line agent)
Must consider: caffeine use - additive effect
cigarettes - inhibition of cyp -> increased toxicity
Target concentration of theophylline and toxic concentration
5-15 mcg/ml
>20 mcg/ml -> toxicity: tachycardia, restlessness, agitation, emesis, seizure
Roflumilast
PDE-4 inhibitor
-> accumulation of cAMP -> smooth muscle relaxation
P450 metabolism
Bronchodilation and anti-inflammatory effect - treatment for COPD
Cromolyn - mechanism and time to onset of activity.
Mast cell stabilizer - takes 1week for full effect
Does not have bronchodilatory, anti-histaminic, or corticosteroid effects.
Omalizumab - what it is and how administered
humanized monoclonal antibody to IgE
Good for pts. w/ comorbid allergies
Subcutaneous injection - expensive
Combivent
Combination MDI
Ipratropium / Albuterol combo - COPD quick relief
Advair
Salmeterol / Fluticasone - DPI, MDI
COPD and Asthma controller
Symbicort
Formoterol + Budesonide
DPI for asthma and COPD
Controller
Dulera
Mometasone + Formoterol
MDI asthma controller
Breo Ellipta
Fluticasone + Vilanterol
DPI
COPD controller
What racial / ethnic groups have the highest incidence of TB infection?
- Asian
- Hispanic
- African American
What toxins are produced by TB?
None
But it does produce niacin - old ID Method
What is the most common mycobacterial infection in AIDS?
MAC: mycobacterium avium complex
consists of M. intracellulare and M. avium
risk of infection when CD4 is <50
Disseminated infection
What are some Non-Tuburculous Mycobacteria species and associated diseases?
M. scrofulaceum - Lymphadenitis
M. marinum and M. ulcerans - cutaneous disease
MAC - disseminated disease in HIV pts.
What NTM pathogen causes pulmonary disease in CF?
M. abscessus
person to person spread in CF centers
What NTM is most similar to TB?
M. kansasii
not treated with PZA
What is the source of NTM spread?
Water and soil source - no person to person
TB infection depends on what 3 factors?
Number of droplet nuclei exposed to
Number of TB organisms in droplet nuclei
Duration of exposure
5 measures for preventing TB infection
Ventilation (neg. pressure isolation) >20 air volume changes per hour
UV light
Chemotherapy: 1-2 weeks of therapy prevents infectivity
Covering infected person’s mouth
Masks
What % of people w/ TB exposure become infected? What % of those develop TB?
1/3 become infected (pos skin test or IGRA)
Of those: 10-15% develop TB
Of those: 50% develop early (w/in 2 years), 50% late
How long does it take to develop a positive skin test after TB exposure?
3-8 weeks
Describe the course of infection of TB from exposure to disease manifestation
Inhalation -> lung -> lymph -> blood and spread
Macrophage endocytosis -> multiplication, inhibition of phagolysosome formation -> macrophage death and realease
3 weeks: Th1 response: IFN-gamma-> macrophage activation and phagolysosome formation - mycobacteria destruction
Macs release TFN-a: increases monocyte response
relative immunity
Describe TB skin testing
Mantoux Method:
Intracutaneous injection of 5 Tuberculin Units (TU) of PPD (Purified Protein Derivative)
Induration measured after 48-72 hours
What is a positive TB skin test?
5,10, and 15 mm induration depending on risk
High risk: 5mm (close contact of infected, HIV, immune suppressed, etc)
Low-moderate risk: 10mm (health care workers, skin test conversion, recent immigrants from endemic areas, children <4yrs)
Low risk: 15mm: no risk factors - targeted skin testing not recommended.
What should be done if TB is suspected?
3 sputum sample collections at least 8 hrs apart w/ one first morning sample
Order: AFB test and culture for mycobacteria
What are the fastest turn-around tests for TB?
AFB: Acid fast bacillus stain can be completed in 24-48 hrs
Direct Nucleic Amplification Test on sputum sample: 24-48 hrs
What are the shortcomings of AFB staining?
Low sensitivity and Low specificity: produces both false + and -
What is the definitive diagnostic test for TB and how long does it take to complete?
Culture and sensitivity
Very slow: 1-2 weeks. maybe up to 6-8 weeks
4 major TB drugs
Isoniazid (INH)
Rifampin (RIF)
Pyrazinamide (PZA)
Ethambutol (EMB)
What is multi-drug resistant TB?
Resistant to AT LEAST Rifampin and Isoniazid
What is XDR-TB?
Extremely Drug Resistant TB
MDR-TB (resistant to RIF and INH) resistant to any fluoroquinalone
Plus any one of the following injectibles:
Amikacin, Capreomycin, Kanamycin
What is the duration of treatment for TB?
Depends on drugs used, presence of resistance, presence of + cultures after initiation phase, and cavitary or HIV add 3 mos.
If RIF and PZA - treat 6 mos
What is initial phase and continuation phase treatment of TB?
Initial: standard 4 drug regimen: INH, RIF PZA, EMB for 2 mos
Continuation: additional 4 months (of RIF / INH) or more if pos culture after initial phase (drugs may differ based on susceptibility)
What is the definition of latent TB?
TB infection w/ no indication of disease
Pos skin test or IGRA
Lifelong risk of TB - assumed persistence of organisms somewhere in body
What is treatment for latent TB?
- 9 mos of Isoniazid @ 300mg / day or 900mg 2/wk
or - 4 mos of Rifampin @ 600 mg / day
watch for Hepatitis
What are risks for disease development in cases of TB infection?
Immune suppression: HIV, transplants, Prednisone (15mg/day for 1month or more, TNF-a agonists (infliximab, etanercept, adalimumab)
Stable x-ray consistent with old healed TB
Children < 4yrs
Silicosis, Diabetes, ESRD, underweight, low dose corticosteroids, cancer of head and neck
What is BCG?
Bacillus Calmette and Guerin - TB vaccine of M.bovis
varies in efficacy
does not prevent infection, but prevents dissemination
What is IGRA and what tests are used?
IFN-gamma release assay
1. QuantiFERON Gold: ELISA to determine IFN-g production in blood sample when Ag added (Ag: ESAT-6, CFP-10, TB7.7)
+: >/= 0.35 IU/mL
-: < 0.35 IU/mL
- T-Spot TB: incubation of peripheral blood monocytes with 2 separate mixtures of peptides (ESAT-6 and CFP-10).
ELISpot detects # of IFN-g secreting cells
+: +/= 8 spots
-: <7 spots
define pneumonia
Inflammation of gas exchanging areas of lung / lower respiratory tract
What is the #1 cause of death from infectious disease?
pneumonia
What is rust colored sputum suggestive of?
Pneumococcal pneumonia
What is “currant jelly” sputum suggestive of?
Klebsiella pneumoniae pneumonia
What is creamy yellow sputum suggestive of?
Staphylococcus pneumonia
What is very foul smelling sputum suggestive of?
Aspiration pneumonia - oral anaerobes
What pneumonia causing organsisms are not seen in sputum?
Mycoplasma, Legionella, TB, viruses
What is treatment for Pneumococcal pneumonia?
Macrolide (azithromycin) or doxycycline
Plus 3rd gen cephalosporin (Cefotaxime, cephtriaxone, cephixime, cefpodoxime
What is type 3 serotype S.pneumo?
Highly virulent strain. Poorer prognosis.
4 groups of community acquired pneumonia
- Outpatient w/o comorbidity 60 yoa. (s.pneumo, mycoplasma)
- Outpatient w/ comorbidity or >60yoa (s.pneumo, virus, h.influ)
- Hospitalized w/ CAP 5-25% mortality
(S.pneumo, H. influenzae, poly (inc. anaerobe), gram -, legionella) - Severe hospitalized - ICU. Up to 50% mortality
(S. pneump, legionella, gram -, resp. viruses)
What does Mycoplasma pneumonia cause?
Atypical or “walking” pneumonia in young otherwise healthy people.
What are clinical symptoms of Mycoplasma pneumonia?
insidious onset
non-productive cough
fever, headache, chills
No leukocytosis
Blistering of eardrum (Bullous Myringitis)
Rare signs of consolidation - usually patchy rales and crackles
How is mycoplasma treated?
Macrolide (azithro, clarithro, erythromycin)
or Tetracycline
What are indicators of Legionella infection?
Fever over 102 w/ relative bradycardia, GI involvement w/ diarrhea, hyponatremia, hypophosphatemia
How is legionella pneumonia treated?
Macrolides- rifampin
What populations are associated with H.influenzae pneumonia?
alcoholics, COPD, healthy adults, sickle cell pts.
Lots of sputum
treat w/ cephalosporin, sulfa
What populations are associated with Klebsiella pneumonia?
Diabetics, alcoholics, debilitated
bulging fissure on cxr
treat w/ cephalosporin or aminoglycoside
In aspiration pneumonia how long does it take following aspiration for tissue necrosis / liquefaction?
~12 days
3 tests for Cocciodiomycosis
Skin test: Positive bet. 3 days and 3 weeks after onset.
- *- change to +: new infection
- *+ change to -: severe infection or dissemination
IgM titer: latex agglutination: + w/in 2-4 weeks of infection
IgG titer: complement fixation: + w/in 8 weeks after infection
diagnostic and prognostic. high titer - high prob. of disseminated disease
2 forms of cocciodiomycosis
arthrospore- in soil, infectious
spherule - tissue form - contains endospores
2 forms of histoplasmosis
microconidia: infective form in soil. assoc. w/ bird and bat droppings
narrow-necked budding yeast: tissue form
What are 2 forms of blastomycosis?
dumbell shaped yeast
broad based budding yeast (tissue)
How is blastomycosis diagnosed?
Serologic testing: not useful - high titer may inappropriately indicate disease
Skin testing: not useful - frequently indicates histoplasmosis
Culture: definitive. fast growing and easy to culture
How is blastomycosis treated?
Usually no antifungal needed.
Only in disseminated disease - IV anti-fungal
How is aspergillus diagnosed?
Skin testing for acute infection
Serology: IgE in acute and fungus balls. IgG also possible
4 types of aspergillus infection and treatments
- Hypersensitive pneumonitis / Extrinsic Allergic Alveolitis - cough, fever, dyspnea, chills w/in 4-6 hrs of exposure
- treat w/ steroids - Allergic Bronchopulmonary Aspergillosis (ABPA) - pts. w/ long standing asthma. + skin, + serology, migratory CXR infiltrates. Cough up brown plugs. Treat w/ steroids
- Aspergilloma - fungus ball. bleeding due to erosion. Surgical removal
- Invasive aspergillosis - only in immunocompromised. Culture for Dx. multiple IV antifungals. High mortality.
What organisms are associated w/ nosocomial pneumonia?
60% enteric gram (E. coli, Klebsiella, enterobacter, pseudomonas, Serratia, Proteus)
10% S. aureus
Legionalla and other
What is the most common viral infection seen in AIDS pts?
CMV
In what patients is P.carinii seen?
HIV: slowly progressive, fever, cough, dyspnea, CXR infiltrate
Children w/ leukemia: fulminant downhill course
What is treatment for P.carinii?
TMP/SMX
Pentamidine IV or aerosol for those who can’t tolerate.
How is INH activated, how does it work, how metabolized?
Activated by mycobacterium
mycobacterial catalase-peroxidase (KatG)
Action: interferes w/ mycolic acid synthesis (bactericidal against actively growing organisms, bacteriostatic against non-replicating)
Metabolism: N-acetyltransferase
What is Rifampin’s MOA?
binds B-subunit of bacterial DNA dependent RNA-pol
What lab values are elevated in Rifampin toxicity? What about Isozianid?
Rifampin: elevated bilirubin and alkaline phosphatase
Isoniazid: aminotransferase elevated
What options are available if there are concerns about Rifampin and DDI?
Rifapentene and Rifabutin - less likely to cause interactions
Rifabutin is usually used.
Rifampin > Rifapentene > Rifabutin
What are some examples of drugs that Rifampin interferes with?
Rifampin induces many CYP450 enzymes
Decreases concentrations of: warfarin, cyclosporine, HIV meds (esp. protease inhibitors), anticonvulsants, oral contraceptives.
What is Pyrazinamide’s MOA?
Unknown. Prodrug activated by mycobacterial pyrizinamidase -> active pyrazinoic acid.
High activity at acidic pH in lysosomes
What is the MOA of Ethambutol?
Inhibits arabinosyl transferases - needed for cell wall components.
What was the first drug useful against TB, what class, what MOA?
Streptomycin (Aminoglycoside) binds 30s subunit of bacterial ribosome - oxygen dependent
ototoxicity
What limits streptomycin use in TB infections?
Rapid development of resistance - 80% of RIF / INH resistant strains are streptomycin resistant.
Does not work intracellularly
Vestibular toxicity - watch for gait abnormalities
What are the differences between Rifampin, Rifabutin and Rifapentene?
Rifabutin: more potent than Rifampin, 50% less CYP450 induction
Rifapentene: long half-life: 1x /week option for HIV - patients. Between Rifabutin and Rifampin in CYP450 induction
4 major cell types associated w/ asthma
Mast cells - histamine, LT, PG, PAF
Eosinophils - MBP, eosinophil cationic protein
Macrophage - cytokines, ROS, PAF, act as APC
TH2: IL 4, 5, GM-CSF
What systems innervate airway sm. muscle?
Parasympathetic: maintains tone. PS constricts airways.
Sympathetic: relaxes airways. Small role in humans.
Nonadrenergic Noncholinergic Neural pathways: mediate tone
-NO and VIP are inhibitory
- Substance P and neurokinins A and B are excitatory
–nerve injury secondary to inflamm -> increased excitatory input, bronchoconstriction and vascular permeability
How long does the early asthmatic response last?
resolves by 2 hours
How often does the late phase asthmatic response occur and how long does it last?
Occurs in 50% of asthmatics
Occurs w/in 6-8 hrs and may last up to 24 hours
3 causes of airway obstruction in asthma
- bronchospasm
- vascular congestion and bronchial edema
- accumulation of airway secretions, mucus casts, and cellular debris
What happens to PFTs during an asthma attack?
Reduced FEV1 and FVC
Reduced FEV1/FVC
Lung volume increase, esp RV and FRC
How does the work of breathing change in asthma?
Increases
- Flattened diaphragm w/ hyperinflation - no longer optimal length/tension relationship
- Hyperinflated lungs shift on compliance curve -> require more pressure for change in volume
- V/Q mismatch -> hypoxemia and dead space
What is criteria for intermittent asthma?
Rule of 2:
symptoms < / = 2x /week
night time awakenings </= 2 days per week
What are the 3 levels of persistent asthma?
Mild: symptoms >2x week, not daily, awakening 3-4/mo, B2 ag >2x/ week, not more than 1x/ day
Moderate: symptoms daily, awakening >1x/week, b2 daily
Severe: symptoms throughout day, awakening daily, b2 multiple/ day
What is the goal of asthma therapy and what are its components?
Goal: control
- Impairment: prevent symptoms, minimize use (<2/week) of SA B2 agonists
- Risk: minimize hospital visits and pulmonary function decline, minimize adverse medical effects
What is the only major disease in US w/ an increasing death rate?
COPD
4th most common cause of death
What % of chronic heavy smokers develop COPD?
10-15%
Genetic component
What chromosome is implied in families w/ COPD?
What other polymorphisms have been identified?
2q
IL1, TGF-B (both increasing and decreasing risk), GSTM-1
Where is a1-antitrypsin gene found? Is deficiency AD or AR?
on chromosome 14
AR
What other organ system is affected in persons w/ a1-antitrypsin deficiency emphysema?
Hepatic cirrhosis is seen in 1-3% of emphysema pts.
What is the role of oxidative stress in COPD?
- activates NFk-B -> transcription of inflammatory proteins (TNF-a)
- inactivation of anti-proteases
What is the role of amplification in COPD?
COPD patients have amplified inflammatory response compared to normal.
3 key symptoms for COPD diagnosis
- chronic cough
- chronic sputum production
- dyspnea: starts insidiously and escalates - persistent
What is the most common cause of COPD exacerbation?
bacterial or viral infection of airways
What is the most common genotype of a1-antitrypsin deficiency? What is normal?
PiZZ (homozygous, disease is AR): in 90-95% of cases
PiMM is normal
What chromosome houses the genes associated with a1-antitrypsin deficiency?
14
What inflammatory cells are associated with COPD?
Macrophage (critical)
CD8 Lymphocyte
Neutrophil
What changes in V/Q are seen in COPD?
Both high and low
High: increased dead space (V/Q -> infinity)
Low: hypoxemia, shunt (V/Q -> 0)
What are major considerations for COPD diagnosis?
Chronic cough Sputum Recurrent bronchitis Dyspnea - persistent, progressive, worse w/ exertion Exposures - smoking
When should ABG be checked in COPD evaluation?
FEV1 <40%
signs of Cor Pulmonale / Right sided HF
During exacerbations
What is a chronic CO2 retainer?
COPD patient with elevated PCO2 between exacerbations
Blood gas reflects compensated respiratory acidosis (normal pH, high HCO3-
Why do people lose weight in COPD?
Loss of skeletal muscle, particularly in limbs
- increased TNF-a, increased metabolism
- seen in 50% w/ severe disease, 10-15% in mild-moderate
- inverse relationship w/ survival
5 etiologies of bronchiectasis
- infection: Pertussis, necrotizing pneumonia, viral pneumonia (measles, influenza), TB
- Immotile cilia syndrome / Kartagener’s
- Hypogammaglobulinemia
- Cystic Fibrosis (frequent infections w/ S.aureus and PSA)
- Allergic bronchopulmonary aspergillosis
How is bronchiectesis detected?
CT scan reveals dilated bronchi that do not taper toward periphery.
CXR is not reliable, though increased bronchovascular markings and cystic air spaces are suggestive.
Treatment for bronchiectasis?
- Treat underlying problem
- Improve clearance of secretions: chest physiotherapy
- Control infections: vaccinations, daily abx (CF - macrolide 3x/wk)
- Bronchodilators
From what tissue do lungs develop?
Foregut endoderm
buds at ~4weeks
3 stages of lung development
Pseudoglandular 5-16 wks
Canalicular 16-26 wks
Alveolar / Viable 26- birth
What test is used to asses lung maturity prenataly?
Lecithin: sphingomyelin
Lecithin increases w/ maturation, sphingomyelin stays stable
What substances accelerate fetal lung maturation?
cortisone, stress, thyroxine, prolactin, theophylline, sympathomimetics
3 factors that decrease rate of fetal lung maturation
Insulin
Metapyrone
Barbiturates
At what age are all alveoli formed?
~10
few alveoli at birth
8-10 yrs - intense alveolar prolif
10-20 increase in size
What is a tracheal-esophageal fistula and when is it formed?
Failure of separation of esophageal and lung buds from foregut. Abnormal connection between trachea and esophagus.
Insult at ~4th week
When would failure of a lung or lobe to develop occur and what are the ramifications?
Insult ~4-8 weeks gestation
Generally asymptomatic (60% reserve at max exercise in normal) but reduced reserve - sx, trauma, infection