UWorld 2017

Question 1

Cyanide poisoning

Answer 1

Ttt: Nitrites (oxidizing agents) induce methemoglobenemia (Fe3+)
Cyanide binds to Fe3+ in MetHb more than to mito cytochrome enzymes which diminishes cyanide’s toxic effect

Question 2

Oxygen loading + unloading

Answer 2

Lungs: binding of O2 to Hb releases H+ and CO2 (Haldane eff)

Periph tissue: high CO2 and H+ facilitate O2 unloading from Hb (Bohr)

Question 3

Pulmonary anthrax

Answer 3

Inhalation of spores (from goat hair)
Hemorrhagic mediastinitis
Micro: long chains (serpentine, medusa head)
Bact: antiphagocytic capsule (D-glutamate) for pathogenicity. Not polysaccharide

Question 4

Level of thoracocentesis

Answer 4

Above 8th rib in midclav, 10th in midaxill, 12thnin post scapular
Needle lower: high risk of penetrating abdo
Needle on inf margin of rib: striking subcostal neurovascular bundle

Question 5

Corticosteroids in asthma

Answer 5

Strongest effect on inflammatory component

Inhaled CS: as chronic ttt for persistant asthma, reduce nb+severity of acute exacerbations

Question 6

pO2 in LA < pulm cap

Answer 6

Mixing oxyg blood from pulm veins w/ deO2 blood from bronchial circulation and thebesian veins

Question 7

From apex to base

Answer 7

Perfusion greatly increases
Ventilation increases slightly
V/Q decreases

Question 8

Omalizumab

Answer 8

Effective add-on ttt in severe allergic asthma

Reduce dep on oral + inhaled CS

Question 9

Perfusion-limited and diffusion-limited

Answer 9

pO2 trachea 150, pO2 alveole 104: equilib in normal is perf-lim
Diff-lim: emphysema, pulm fibrosis, very high pulm blood flow (exercise)