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USMLE Step 1 > Respiratory Random > Flashcards

Flashcards in Respiratory Random Deck (48):
1

Collapsing pressure =

(2T)/r

2

Surfactant synthesis starts at ___ and reaches mature levels at ____

26 weeks; 35 weeks

3

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

greater than 2

4

Inhalation obstruction (standing/supine)

Standing - lower part of right inferior lobe
Supine - upper part of right inferior lobe

5

Pulmonary artery relation to bronchi at hilum

RALS
right - anterior
left - superior

6

Diaphragm perforations

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

7

Common bifurcations

Internal carotid - C4
Trachea - T4
Aorta - L4

8

Physiologic dead space (Vd) =

Vt x ((PaCO2 - PeCO2)/PaCO2

9

Minute ventilation (Ve) =

Vt x respiratory rate (RR)

10

Alveolar ventilation (Va) =

(Vt - Vd) x RR

11

When is PVR at a minimum?

Functional residual capacity

12

Taut vs Relaxed

deoxygenated vs oxygenated

13

Cyanosis and Chocolate coloured blood

Methemoglobinemia

14

Carboxyhemoglobin

CO + Hb

15

Oxygen content of blood =

(O2 binding capacity x % sat) + dissolved O2

16

Normal O2 binding capacity

20.1 mL O2/dL

17

O2 delivery to tissues =

CO x O2 content of blood

18

Diffusion (Vgas) =

A/T x Dk(P1-P2)

19

Blood gas changes CBF

CO2 under 100
O2 under 50

20

PVR =

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

21

Resistance =

8nl / 3.14 r^4

22

Alveolar gas equation (PAo2) =

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

23

Normal A-a gradient

10-15 mmHg

24

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

0 - no
infinity - yes

25

Carbaminohemoglobin

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

26

Haldane effect

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

27

Bohr effect

Metabolism shifts curve to right, unloading oxygen

28

EPO compensation

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

29

Charcot-Leyden crystals

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

30

Unique asthma findings

Pulsus paradoxus and decreased inspiratory/expiratory ratio

31

Lymphocytes mediating asthma?

Th2

32

Hypersensitivity pneumonitis

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

33

Caplan syndrome

RA + pneumoconioses with intrapulmonary nodules

34

Furruginous bodies

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

35

Anthracosis

Asymptomatic; sooty air; urban dwellers

36

Silicosis unique

- Increases susceptibility to TB
- Eggshell calcification of hilar lymph nodes

37

Maternal diabetes on surfactant

Increased fetal insulin inhibits surfactant production

38

Therapeutic supplemental O2 in NRSD

RIB
- Retinopathy of prematurity
- Intraventricular hemorrhage
- Bronchopulmonary dysplasia

39

Normal pulmonary artery pressure and PH

10-14 mmHg
greater than 25

40

Plexiform lesions

Tufts of capillaries with long-standing PH

41

Idiopathic PAH inheritance

Inactivating mutation of BMPR2 gene (inhibits vasc SM prolif)

42

Metastases FROM lung

Adrenals, brain, bone, liver

43

Matastases TO lung

breast, colon, prostate, bladder

44

Small cell (oat cell) carcinoma

- 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

Adenocarcinoma

- Activating mutations KRAS, EGFR, ALK
- Bronchoalveolar subtype = in situ
- Mucin (+)

46

Squamous Cell carcinoma

- Cavitation
- Cigarettes
- hyperCalcemia (PTHrP)

47

Large Cell carcinoma

- Possibly beta-hCG

48

Bronchial carcinoid tumor

Nest of neuroendocrine cells (chromogranin A (+))