Section 3: Flashcards
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
List the typical physical findings in COPD
Barrel-shaped chest
Clubbing of fingers Increased anterior-posterior diameter of the chest Loud P2 heart sound (sign of pulmonary hypertension)
Edema as a sign of decreased right ventricular output (the blood is backing up due to the pulmonary hypertension)
Laboratory findings in COPD
EKG: Right axis deviation, right ventricular hypertrophy, right atrial hypertrophy
Chest x-ray: Flattening of the diaphragm (due to hyperinflation of the lungs), elongated heart, and substernal air trapping
CBC: Increased hematocrit is a sign of chronic hypoxia. Reactive erythrocytosis from chronic hypoxia is often microcytic. An erythropoietin level is not necessary.
Chemistry: Increased serum bicarbonate is metabolic compensation for respiratory acidosis.
ABG: Should be done even in office-based cases to assess CO2 retention and the need for chronic home oxygen based on pO2 (you expect the pCO2 to rise and the pO2 to fall).
Pulmonary function testing (PFT): You should expect to find the following:
– Decrease in FEV1
– Decrease in FVC from loss of elastic recoil of the lung
– Decrease in the FEV1/ FVC ratio
– Increase in total lung capacity from air trapping
– Increase in residual volume
– Decrease in diffusion capacity lung carbon monoxide (DLCO) caused by destruction of lung interstitium
Chronic medical therapy for COPD
Tiotropium or ipratropium inhaler
Albuterol inhaler
Pneumococcal vaccine: Heptavalent vaccine,
Pneumovax Influenza vaccine: Yearly
Smoking cessation
Long-term home oxygen if the pO2 < 55 or the oxygen saturation is < 88 percent
Name two interventions that lower mortality in COPD
Smoking cessation
Home oxygen therapy (continuous)
Spot Diagnosis: A case of COPD at an early age (< 40) in a nonsmoker who has bullae at the bases of the lungs.
Alpha-1 antitrypsin deficiency
Rx for alpha-1 antotrypsin deficiency
Alpha-1 antitrypsin infusion
What is the most accurate diagnostic test for bronchiectasis?
High-resolution CT scan of the chest.
Medication associated with lung fibrosis
Nitrofurantoin
What is the most common type of cancer in asbestosis?
Lung Cancer
(NOT MESOTHELIOMA)
Causes of silicosis
Glass workers
Mining
Sandblasting
Brickyards
Causes of berylliosis
Electronics
Ceramics
Fluorescent light bulbs
Name the interstitial lung disease caused by mercury
Pulmonary fibrosis
Name the interstitial lung disease caused by cotton
Byssinosis
Enumerate the PFT in ILD
Decreased FEV1
Decreased FVC
FEV1/FVC ratio is normal or increased
Decreased total lung capacity
Decreased DLCO
All the measures are decreased, but they are decreased proportionately.
List and explain the rare physical findings in Sarcoidosis
Eye: Uveitis that can be sight threatening
Neural: Seventh cranial nerve involvement is the most common.
Skin: Lupus pernio (purplish lesion of the skin of the face), erythema nodosum
Cardiac: Restrictive cardiomyopathy, cardiac conduction defects
Renal and hepatic involvement: Occurs without symptoms
Hypercalcemia: This occurs in a small number of patients secondary to vitamin D production by the granulomas of sarcoidosis.
Best initial test for Sarcoidosis
Chest x-ray, which always shows enlarged lymph nodes.
Most accurate diagnostic test for Sarcoidosis
Lung or lymph node biopsy showing noncaseating granulomas.
Other important but non-specific tests for Sarcoidosis
Calcium and ACE levels may be elevated, but these are not specific enough to lead to a specific diagnosis.
Bronchoalveolar lavage shows increased numbers of helper cells.
Therapy for Sarcoidosis
Steroids
Secondary causes of pulmonary hypertension
Mitral stenosis
COPD
Polycythemia vera
Chronic pulmonary emboli
Interstitial lung disease
Physical findings in pulmonary hypertension
Loud P2
Tricuspid regurgitation
Right ventricular heave
Raynaud’s phenomenon
List and explain diagnostic tests in pulmonary hypertension
Transthoracic echocardiogram (TTE): Shows right ventricular hypertrophy and enlarged right atrium
EKG: Shows the same findings as well as right axis deviation
Most accurate test: Right heart catheterization (Swan-Ganz catheterization) with increased pulmonary artery pressure
Enumerate Rx for pulmonary hypertension
Bosentan is an endothelin inhibitor that prevents growth of the vasculature of the pulmonary system.
Epoprostenol and treprostinil are prostacyclin analogs that act as pulmonary vasodilators.
Calcium channel blockers (weak efficacy)
Sildenafil
Describe pulmonary embolism (PE)
PE presents with the sudden onset of shortness of breath and clear lungs in patients with risk factors for deep venous thrombosis (DVT).
List the risk factors for DVT
Immobility
Malignancy
Trauma
Surgery, especially joint replacement
Thrombophilia, such a factor V mutation, lupus anticoagulant, or protein C and S deficiency
What are the specific physical findings in PE?
None
Diagnostic tests for PE
Chest x-ray: The most common result is normal. The most common abnormality found is atelectasis. Wedge-shaped infarction and pleural-based humps are rare.
EKG: The most common showing is sinus tachycardia. The most common abnormality is nonspecific ST-T wave changes. Right axis deviation and right bundle branch block are uncommon.
ABG: This shows hypoxia with an increased A-a gradient and mild respiratory alkalosis.
List and explain the confirmatory test for PE
Spiral CT
A spiral CT is standard to confirm the presence of a pulmonary embolus. The spiral CT is excellent if it is positive because of its specificity. The sensitivity of spiral CT may not be ideal, and the test can miss some emboli if they are small and in the periphery. The spiral CT is clearly the test of choice if the x-ray is abnormal.
V/ Q Scan
For a V/ Q scan to be accurate, the chest x-ray must be normal. The less normal the x-ray, the less accurate the V/ Q scan. This is still a good test for PE. The problem is that only a truly normal scan excludes a PE. Of patients with low-probability scans, 15 percent still have a PE, and 15 percent of those with of high-probability scans don’t have a PE.
Lower Extremity Doppler
These are excellent tests if they are positive; if positive, no further diagnostic testing is necessary. The problem is that 30 percent of PEs originate in pelvic veins, and the Doppler scan is normal even in the presence of a PE. Hence, the sensitivity of lower extremity Doppler is about 70 percent.
D-Dimer Testing
This is a very sensitive test with poor specificity. If the D-dimer is negative, PE is extremely unlikely. The best use of D-dimer testing is in a patient with a low probability of PE in whom you want a single test to exclude PE.
Angiography
Angiography is the single most accurate test for PE. Unfortunately, angiography is invasive with a significant risk of death of about 0.5 percent.
When a patient has a pulmonary embolism and there is a contraindication to anticoagulation, what should be the next line of action?
Place an inferior vena cava filter
Outline the Rx for PE
Heparin and oxygen: This is the standard of care in pulmonary embolism.
Warfarin: Should be used for at least 6 months after the use of heparin.
Venous interruption filter: This should be placed in all patients who have a contraindication to anticoagulation.
Thrombolytics: These are used in patients who are hemodynamically unstable. Hemodynamic instability can be defined as hypotension. Thrombolytics essentially replace embolectomy, which is rarely performed because of the high operative mortality.
