Section 5: Flashcards
Most likely organism for community-acquired pneumonia (CAP)
Pneumococcus
Most likely organism for hospital-acquired pneumonia (HAP)
Gram negative bacilli
Diagnostic tests for pneumonia
Best initial diagnostic test: Chest x-ray
Most accurate test: Sputum Gram stain and culture
Order tests as follows: All cases of respiratory disease (fever, cough, sputum) should have a chest x-ray and oximeter ordered with the first screen.
If there is shortness of breath, also order oxygen with the first screen.
If there is shortness of breath and/ or hypoxia, order an ABG.
Rx for outpatient pneumonia
Macrolide (azithromycin, doxycycline, or clarithromycin)
Respiratory fluoroquinolone (levofloxacin, moxifloxacin)
Rx for inpatient pneumonia
Ceftriaxone and azithromycin
Fluoroquinolone as a single agent
What is ventilator-assisted pneumonia (VAP)?
- Fever
- Hypoxia
- New infiltrate
- Increasing secretions
Rx for VAP
- Imipenem or meropenem, piperacillin/ tazobactam or cefepime;
- Gentamicin; and
- Vancomycin or linezolid
When is steroid indicated in PCP?
Steroids are indicated if the pO2 < 70 or the A-a gradient > 35.
Patient with pneumonia who had a recent viral infection, what is the likely causative agent?
Staphylococcus
Patient with pneumonia who is an alcoholic, what is the likely causative agent?
Klebsiella
Patient with pneumonia who has gastrointestinal symptoms and confusion, what is the likely causative agent?
Legionella
Young healthy patient with pneumonia, what is the most likely causative organism?
Mycoplasma
Patient with pneumonia who was present at the birth of an animal, what is the likely causative agent?
Coxiella burneti
Pneumonia in an Arizona construction worker, what is the likely causative agent?
Coccidioidomycosis
HIV Patient with pneumonia with a CD4+ count less than 200, what is the likely causative agent?
PCP
Risk groups for tuberculosis (TB)
Immigrants
HIV-positive patients
Homeless patients
Prisoners
Alcoholics
Diagnostic tests for TB
Best initial test: Chest x-ray
Sputum acid-fast stain and culture should be done to confirm the presence of TB
Rx for TB
Once the acid-fast stain is positive, treatment with 4 antituberculosis medications should be started. Six months of therapy is the standard of care.
- Isoniazid (INH): 6 months
- Rifampin: 6 months
- Pyrazinamide: Stop after 2 months
- Ethambutol: Stop after 2 months
List the complications of TB medications
Isoniazid: Peripheral neuropathy
Rifampin: Red/ orange-colored bodily secretions
Pyrazinamide: Hyperuricemia
Ethambutol: Optic neuritis
All of these medications can lead to liver toxicity. TB medications should be stopped if the transaminases reach 5 times the upper limit of normal
Under what conditions should TB Rx be extended beyond 6 months
Osteomyelitis
Meningitis
Miliary tuberculosis
Cavitary tuberculosis
Pregnancy
Diagnostic tests for latent TB
The PPD is a screening test for those in risk groups, such as the homeless, immigrants, alcoholics, health care workers, and prisoners. A positive test is as follows:
5 mm: Close contacts, steroid users, HIV-positive
10 mm: Those in the risk groups described above
15 mm: Those without an increased risk
If a patient has never been tested or it has been several years since the last test, 2-stage testing is recommended. This means that if the first test is negative, a second test should be performed in 1– 2 weeks to make sure the first test was truly negative.
What are te steps to follow for a positive PPD?
If the PPD is positive, proceed as follows:
- A chest x-ray should be performed to make sure occult active disease has not been detected.
- If the chest x-ray is abnormal, sputum staining for tuberculosis is performed.
- If this is positive, then full-dose, 4-drug therapy is used.
Isoniazid alone is used for 9 months to treat a positive PPD. This reduces the 10 percent lifetime risk of developing tuberculosis to 1 percent. Once a PPD is positive, the test should never be repeated.
What other screening tests can be performed in place of PPD?
Interferon gamma release assay (IGRA) (Quantiferon) is an in-vitro blood test that is used for the detection of latent tuberculosis. The indication for an IGRA is the same as for a PPD. The main difference is that the IGRA is more specific than a PPD. There are no false positives on an IGRA with previous BCG infection.
Bacille-Calmette Guerin (BCG) administration in the past has no effect or influence on these recommendations for treatment of latent TB. It does not matter if a patient has had BCG in the past; the patient must still take isoniazid if the PPD is positive. If BCG is an answer choice, it is always wrong according to current guidelines.
IGRAs have a 90 percent sensitivity for previous TB exposure. A positive test is treated with INH alone. A positive IGRA does not mean active infection. As with a PPD, a positive IGRA confers only a 10 percent lifetime risk of TB.
Diagnosis: Decreased TLC, Decreased RV, Decreased VC, Normal FEV1, Normal FEV1/FVC ratio, Normal DLCO
Extra-parenchymal (extra-thoracic) restriction
- Kyphosis
- Obesity
Diagnosis: Increased TLC, Increased RV, Decreased FEV1, Decreased FVC, Decreased FEV1/FVC ratio, Decreased DLCO
COPD
Diagnosis: Normal or Increased TLC, Normal or Increased RV, Decreased FEV1, Decreased FVC, Normal or Decreased FEV1/FVC ratio, Normal or Increased DLCO
Asthma
Diagnosis: Decreased TLC, Decreased RV, Decreased FEV1, Decreased FVC, Normal or Increased FEV1/FVC ratio, Decreased DLCO
Fibrotic (or Interstitial Lung) Disease
List the minimum that should be done for all patients with shortness of breath (SOB)
Oxygen
Continuous oximeter
Chest X-ray
Arterial blood gas (ABG)
Causes of low DLCO
Emphesema
Pneumonectomy
Interstitial lung disease
pulmonary embolism
Pulmonary HTN
Arterial blood gases measurements
pH: 7.35 to 7.45
PCO2: 33-45mmHg
PO2: 75-105mmHg
Which is the only form of interstitial lung disease that responds to steroid and why?
Berryliosis, because it is a granulomatous disease
List the diagnostic tests in ILD and explain the findings in each test
CXR: interstitial fibrosis
High-resolution CT scan: more detail of interstitial fibrosis
Lung biopsy
PFT
What is BOOP?
Bronchiolitis obliterans organizing pneumonia
What is another name for bronciolitis obliterans organizing pneumonia (BOOP)?
Cryptogenic organizing pneumonia (COP)
Compare BOOP/COP and ILD
- Fever, myalgias, malaise (clubbing uncommon) present in BOOP; No fever, no myalgias in ILD
- Symptoms presents over days to weeks in BOOP; Symptoms present over six months or more in ILD
- Patchy infiltrates in BOOP; Interstitial infiltrates in ILD
- Steroids effective in BOOP; ILD rarely responds to steroids
The two most common lung cancers
Adenocarcinoma
Squamous cell carcinoma
Centrally located lung carcinomas
Squamous cell ca
Small cell ca
What lung ca is associated with Eaton-Lambert syndrome, syndrome of inappropriate antidiurectic hormone and other paraneoplastic syndromes
Small cell ca
Type of lung ca most commonly associated with venocaval obstruction syndrome
Small cell ca
Peripherally located lung cancers
Large cell carcinoma
Adenocarcinoma
Lung ca associated with cavitation
Large cell ca
Lung ca associated with pleural effusion with high hyaluronidase levels
Adenocarcinoma
Most common initial presentation of cystic fibrosis
Meconium ileus
Other clinical features of cystic fibrosis
Failure to thrive
Rectal prolapse
Persistent cough
May also present with
- Infertility
- Allergic bronchopulmonary aspergillosis
Best initial and most specific test
2 elevated sweat chloride concentrations (> 60 mEq/ L) obtained on separate days.
Fischer, Conrad (2012-09-22). Master the Boards: USMLE Step 3 (Kindle Locations 11299-11300). . Kindle Edition.
List the supportive care in the Rx of cystic fibrosis
Aerosol treatment
Albuterol/ saline
Chest physical therapy with postural drainage
Pancrelipase: Aids digestion in patients with pancreatic dysfunction.
Fischer, Conrad (2012-09-22). Master the Boards: USMLE Step 3 (Kindle Locations 11308-11309). . Kindle Edition.
List and explain Rx that improve survival in patients with cystic fibrosis
Ibuprofen is used to reduce inflammatory lung response and slows the patient’s decline.
Azithromycin has also been shown to slow rate of decline in FEV1 in patients < 13 years.
Antibiotics during exacerbations delay progression of lung disease.
Fischer, Conrad (2012-09-22). Master the Boards: USMLE Step 3 (Kindle Locations 11311-11314). . Kindle Edition.
What are the other management considerations in cystic fibrosis
Give all routine vaccinations plus pneumococcal and yearly flu vaccines.
Never delay antibiotic therapy (even if fever and tachypnea are absent).
Steroids improve PFTs in the short term, but there’s no persistent benefit when steroids are stopped.
Expectorants (guaifenesin or iodides) are not effective in the removal of respiratory secretions.
Fischer, Conrad (2012-09-22). Master the Boards: USMLE Step 3 (Kindle Locations 11316-11318). Kindle Edition.
Antibiotics to Rx cystic fibrosis
Mild disease: Give macrolide, trimethoprim-sulfamethoxazole (TMP-SMX), or ciprofloxacin
Documented infection with Pseudomonas or S. aureus: Treat aggressively with piperacillin plus tobramycin or ceftazidime
Resistant pathogens: Use inhaled tobramycin.
Fischer, Conrad (2012-09-22). Master the Boards: USMLE Step 3 (Kindle Locations 11319-11326). . Kindle Edition.
Features that indicate benign solitary lung nodule (on chest X-ray): “low risk”
Non-smokers
Lesions
Smooth distinct margins
Calcification typical of benign lesions
- Popcorn: Harmatomas
- Bull’s eye: Granulomas
No change in size of nodule compared to an older X-ray
Features that indicate benign solitary lung nodule (on chest X-ray): “high risk”
>50 years
Lesions >2cm
Smoker
Irregular contours
No calcification
Management of solitary pulmonary nodule
- Find old X-ray for comparison
- If available compare dates and determine doubling time (480 days means beningn lesion)
- Chest X-ray not available: determine low or high risk
- If low risk do spiral CT scan every 3 months for 2 years; nochange - stop CT scans with no further intervention BUT if lesion double manage with open lung biopsy and resection
- If high risk do open lung biopsy and resection
N/B: Doublimg time measures volume and not diameter - doubling time between 1 month and 480 days is suspicious for malignancy
What is A-a gradient?
A-a gradient is alveolar-arterial gradient (PAO2-PaO2 gradient). It is a useful calculation for the assessment of oxygenation. A-a gradient increases with age and is only valid in room air. It is calculated as follows:
PA02-Pa02 gradient = 150 - 1.25 X PaCO2 - PaO2
i.e.,
A-a gradient = [150 - (1.25 X PaCO2) - PaO2]
This gradient is between 5 and 15 mmHg in normal young adults. It increases with all causes of hypoxemia except hypoventilation and high altitude
The diagnosis of allergic bronchopulmonary aspergillosis (ABPA) is based on clinical, radiographic, and immunologic criteria. List them
- A history of asthma
- immediate skin test reactivity to Aspergillus antigen
- Precipitating serum antibodies to Aspergillus fumigatus
- Serum total IgE concentration of greater than 1000 ng/mL
- Peripheral blood eosinophilia greater than 500 per cubic millimeter
- Lung infiltrates, usually involving the upper lobes
- Central bronchiectasis
N/B: If the skin prick test is negative, the diagnosis of ABPA is extremely unlikely
(UW)
