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USMLE Step 1 Systems > Pulm > Flashcards

Pulm Flashcards

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1
Q

How do panic attacks cause sx of anxiety, dizziness, blurred vision, weakness?

A

Hyperventilation! Decreased PCO2 - dec. cerebral perfusion. (CO2 is a cerebral vasodilator).

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2
Q

How does asbestosis present on imaging?

A

Calcified pleural plaques! esp in posterolateral lung zones

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3
Q

What is cheyne-stokes breathing?

A

Cyclic breathing: Apnea -> gradually increasing TV -> gradually decreasing TV -> apnea

Due to slow resp feedback loop and enhanced response to PaCO2 levels.

Seen in Cardiac (CHF) and Neuro (Stroke, Tumor, TBI) Patients!

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4
Q

What causes COPD?

A
  1. Chronic Bronchitis - anatomic narrowing bronchi

2. Emphysema - interalveolar destruction of walls

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5
Q

What happens in respiration when vagal nerve stimulated?

A

Bronchoconstriction & Increased mucus production

-> increased work of breathing.

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6
Q

What cell type generates elastase?

A

PMN!

In smoking induced emphysema, smoking activates PMNS and macrophages to release proteases (elastase) who then generate ROS species that inhibit alpha1antitrypsin. Imbalance of protease-antiproteases = emphysema.

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7
Q

Aspiration pneumonia ends up where supine vs. upright?

A

R > L bronchus
Supine: Posterior upper lobe, Superior lower lobe
Upright: Basilar lower lobe

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8
Q

Aspiration Pneumonia goes where when supine vs. upright?

A

supine - posterior upper lobe, superior lower lobe

upright - basilar lower lobe.

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9
Q

How are dust particles cleared from the lung?

A

Based on size:
< 2 microm = macrophages in alveoli
2.5-10 microm = mucociliary transport
10-15 microm = trapped in upper resp tract

Pneumoconiosis (interstitial fibrosis 2/2 inhalation of inorganic dust) arises bc after macrophages phagocytose the particle, they release cytokines that can induce injury and inflammation -> release of growth factors -> PDGF -> more inflam and fibrosis.

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10
Q

Function of CTFR on apical surface? Nasal Transepithelial potential difference shows?

A

Normal Function:
1. Secretes Cl- into the lumen
2. Causing inhibition of Na channel - decreasing Na absorption
=> Increased Cl, Na, water in the mucus

Nasal Transepithelial Potential Difference: difference btwn resp epithelial surface vs. interstitial fluid = (-) bc of increased Na absorption!

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11
Q

Surfactant acts to ?

A

Decrease surface tension in smaller alveoli as they decrease in size such that they don’t collapse during expiration.

Q477: Ex: P = 2T/r If surface tension is the same, alveoli with smaller radii have greater pressure and will therefore collapse as flow goes high to low pressure.

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12
Q

How to treat severe RSV bronchiolitis in children with immunodef, cardiopulm condition?

A

Warm humidified O2, IVF

Ribavarin - nucleoside analog inhibits synthesis of guanine nucleotides, active against RSV and Hep C

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13
Q

Lung Boundaries (midclav, midax, paravertebral)

A

Midclav: 5-7
Midax: 7-9
Paravertebral: 9-11

First # = lung border
Second # = pleural border
Thoracentesis should be done right above the second numbered rib.

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14
Q

Hypotension, Tachycardia in pt stabbed just above the clavicle?

A

Tension Pneumo!

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15
Q

At what lung volume is pulmonary vascular resistance the lowest?

A

Functional Residual Capacity

U-shaped curve: Q1620

  • increased volume - stretch it so increased length and small diameter
  • decreased volume - narrowed due to traction and compression by intrathoracic pressure from expiration
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16
Q

SVC syndrome vs. braciocephalic vein obstruction?

A

SVC: BILATERAL swelling of face, arms, neck, engorgement of collateral veins

Brachiocephalic: ONE SIDE - R or L

17
Q

What is the difference btwn minute ventilation and alveolar ventilation?

A

Dead space.

Ve = Vt x RR 
Va = Vt-Vd x RR
18
Q

Equilibration of O2 btwn tracheal pO2 and alveolar pO2 (ie diffusion from alveolar pO2 and arterial pO2) is limited how normally vs. in diseased states?

A

Perfusion Limited = Normal O2, CO2 - Reaches diffusion equilibrium before the end of the capillary.
- so if you see that tracheal pO2 and alveolar pO2 are not much different = Perfusion limitation = PE

Diffusion LImited = Emphysema, Pulm Fibrosis

Normal Tracheal pO2 150
Normal Alveolar pO2 104
Normal Alveolar pCO2 40

Q1522

19
Q

How does V/Q change from apex to base?

A

High V/Q at apex – decreases – Low V/Q at base.

Although both V and Q are greater at the base, perfusion changes are relatively greater.

20
Q

What disease is associated with calcified hilar nodes + birefringent particles surrounded by fibrosis?

A

Silicosis

21
Q

Lab value changes at high altitude.

A

Hypoxemia = Low PO2 (~60)
Compensatory Hyperventilation -> Resp Alkalosis
Low PCO2, High pH

22
Q

What should you add on to treat severe allergic asthma?

A

Omalizumab (anti-IgE antibody)

23
Q

Where is airway resistance the lowest in the bronchial tree? highest?

A 
Lowest = terminal bronchioles
Highest = medium sized bronchioles
24
Q

When hemoglobin picks up O2, what dose it release?

A

H+

Haldane effect Q1386

25
Q

Dyplastic columnar cells that grow along alveolar septa without invading stroma or vessels

A

Bronchoalveolar subtype (Adenocarcinoma in situ) of Adenocarcinoma

(considered malignant neoplasm)

26
Q

Pathophysiology of ARDS

A

Diffuse Alveolar Damage - damage to endothelial cells or Type I pneumocytes

Note:
Alveolar wall damage = Emphysema

27
Q

Light Criteria For exudative vs. transudative

A

Exudative:
pleural fluid protein/serum protein > 0.5
pleural fluid LDH/serum LDH > 0.6
LDH > 2/3 upper limit of normal.

If not, transudative.

28
Q

Cromolyn Mechanism of Action

A

Inhibit mast cell degranulation, independent of any stimulus.

29
Q

Why is there absence of peripheral edema in cor pulmonale and increased central venous pressure due to COPD?

A

Increased tissue lymphatic drainage.

30
Q

How to treat pulmonary arterial HTN?

A

Bosentan - antagonize endothelin-1 receptors - vasodilate and dec. pulm vascular resistance.

31
Q

At FRC, what is alveolar/airway pressure and what is intrapleural pressure?

A

Alveolar/Airway pressure = 0
Intrapleural pressure = negative

Tendency for lungs to collapse inward, chest wall to spring outward.

32
Q

How does Reid’s index gauge severity of Chronic Bronchitis?

A

Ratio of thickness of mucous gland layer to the thickness of the bronchial wall btwn the resp epithelium and bronchial cartilage.

33
Q

Small cell carcinoma stains with what?

A

Neuroendocrine derivative - neurofilament, chromogranin, neurophysin.

34
Q

Pt on mechanical ventilation. What would cause resp acidosis with hypoxemia if ventilation parameters are unchanged?

A

Increased dead space ventilation.

Note: ventilation parameters unchanged means that minute ventilation (TV x RR) and FiO2 are unchanged.

35
Q

What is bosentan? Used for?

A

Antagonizes endothelin-1 receptors.

Tx pulmonary arterial hypertension

36
Q

How to differentiate H1 vs. H2 blockers by name?

A

H1: -en/ine or -en/ate
Diphenhydramine, Dimenhydrinate, Chlorpheniramine
Tox: sedation, anti-mus, anti-alpha

H2: - adine
Loratadine, Fenxofenadine, Desloratadine, CETIRIZINE
Less sedating bc less entry into CNS

37
Q

What is dextromethorphan?

A

Antitussive (antagonizes NMDA glutamate receptors) - synthetic codeine analog. Mild opioid effect when used in excess.

38
Q

Asthma Drugs used for bronchodilation

A

b2 agonists: albuterol, salmeterol, formoterol (b2 - cAMP)

methylxanthines: theophylline (inhibits PDE -> more cAMP)

muscarinic antagonists: ipratroprium, tiotroprium (prevent bronchoconstriction, inhibit Ach)

39
Q

Asthma drugs used for decreased inflammation

A

Corticosteroids: beclomethasone, fluticasone
inhibit NFkB

Antileukotrienes:
Montelukast, Zafirlukast –| leukotriene D4 receptors
Zileuton –| lipoxygenase

Omalizumab: monoclonal Ab against IgE

Cromolyn: –| release of mediators from mast cells.

USMLE Step 1 Systems (11 decks)

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