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USMLE Step 1 > Respiratory Random > Flashcards

Respiratory Random Flashcards

1
Q

Collapsing pressure =

A

(2T)/r

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2
Q

Surfactant synthesis starts at ___ and reaches mature levels at ____

A

26 weeks; 35 weeks

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3
Q

Lecithin-to-sphingomylein ratio in amniotic fluid that indicates fetal lung maturity

A

greater than 2

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4
Q

Inhalation obstruction (standing/supine)

A

Standing - lower part of right inferior lobe

Supine - upper part of right inferior lobe

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5
Q

Pulmonary artery relation to bronchi at hilum

A

RALS
right - anterior
left - superior

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6
Q

Diaphragm perforations

A

T8 - IVC
T10 - Eosophagus, CNX
T12 - Aorta, azygos vein, thoracic duct

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7
Q

Common bifurcations

A

Internal carotid - C4
Trachea - T4
Aorta - L4

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8
Q

Physiologic dead space (Vd) =

A

Vt x ((PaCO2 - PeCO2)/PaCO2

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9
Q

Minute ventilation (Ve) =

A

Vt x respiratory rate (RR)

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10
Q

Alveolar ventilation (Va) =

A

(Vt - Vd) x RR

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11
Q

When is PVR at a minimum?

A

Functional residual capacity

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12
Q

Taut vs Relaxed

A

deoxygenated vs oxygenated

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13
Q

Cyanosis and Chocolate coloured blood

A

Methemoglobinemia

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14
Q

Carboxyhemoglobin

A

CO + Hb

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15
Q

Oxygen content of blood =

A

(O2 binding capacity x % sat) + dissolved O2

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16
Q

Normal O2 binding capacity

A

20.1 mL O2/dL

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17
Q

O2 delivery to tissues =

A

CO x O2 content of blood

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18
Q

Diffusion (Vgas) =

A

A/T x Dk(P1-P2)

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19
Q

Blood gas changes CBF

A

CO2 under 100

O2 under 50

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20
Q

PVR =

A

P(pulm art) - P (L atrium) / CO

21
Q

Resistance =

A

8nl / 3.14 r^4

22
Q

Alveolar gas equation (PAo2) =

A

PIo2 - (PaCO2/R)
[at sea level breathing room air] = 150 - (PaCO2/0.8)
R = respiratory quotient = CO2 produced/O2 consumed

23
Q

Normal A-a gradient

A

10-15 mmHg

24
Q

V/Q mismatch (0 or infinity) does 100% O2 improve?

A

0 - no

infinity - yes

25
Q

Carbaminohemoglobin

A

HbCO2 (bound to Hb at N-terminus of globin chain not heme)

26
Q

Haldane effect

A

Oxygenation of Hb promotes H+ dissociation and CO2 formation, releasing it from RBCs

27
Q

Bohr effect

A

Metabolism shifts curve to right, unloading oxygen

28
Q

EPO compensation

A

by 10-14 days arterial O2 content can be restored to normal @ elevations up to 4000m

29
Q

Charcot-Leyden crystals

A

eosinophilic, hexagonal, double pointed needle-like crystals formed by breakdown of eosinophils in sputum

30
Q

Unique asthma findings

A

Pulsus paradoxus and decreased inspiratory/expiratory ratio

31
Q

Lymphocytes mediating asthma?

32
Q

Hypersensitivity pneumonitis

A

Mixed type III/IV HS rxn to environmental Ag causes restrictive lung disease within hours (chronic can cause interstitial fibrosis)

33
Q

Caplan syndrome

A

RA + pneumoconioses with intrapulmonary nodules

34
Q

Furruginous bodies

A

Asbestos bodies; golden brown fusiform rods (dumbells) in alveolar septum

35
Q

Anthracosis

A

Asymptomatic; sooty air; urban dwellers

36
Q

Silicosis unique

A
  • Increases susceptibility to TB

- Eggshell calcification of hilar lymph nodes

37
Q

Maternal diabetes on surfactant

A

Increased fetal insulin inhibits surfactant production

38
Q

Therapeutic supplemental O2 in NRSD

A

RIB

  • Retinopathy of prematurity
  • Intraventricular hemorrhage
  • Bronchopulmonary dysplasia
39
Q

Normal pulmonary artery pressure and PH

A

10-14 mmHg

greater than 25

40
Q

Plexiform lesions

A

Tufts of capillaries with long-standing PH

41
Q

Idiopathic PAH inheritance

A

Inactivating mutation of BMPR2 gene (inhibits vasc SM prolif)

42
Q

Metastases FROM lung

A

Adrenals, brain, bone, liver

43
Q

Matastases TO lung

A

breast, colon, prostate, bladder

44
Q

Small cell (oat cell) carcinoma

A
  • ACTH, SIADH, Ab’s against pre-synaptic Ca channels or neurons (paraneoplastic myelitis/encephalitis)
  • Amplification of myc oncogenes
  • Neoplasm of neuroendocrine Kulchitsky cells
  • Chromogranin A (+), Synaptophysin (+)
45
Q

Adenocarcinoma

A
  • Activating mutations KRAS, EGFR, ALK
  • Bronchoalveolar subtype = in situ
  • Mucin (+)
46
Q

Squamous Cell carcinoma

A
  • Cavitation
  • Cigarettes
  • hyperCalcemia (PTHrP)
47
Q

Large Cell carcinoma

A
  • Possibly beta-hCG
48
Q

Bronchial carcinoid tumor

A

Nest of neuroendocrine cells (chromogranin A (+))

USMLE Step 1 (26 decks)

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