Pulm- RX

Question 1

Explain how the oxygen becomes diffusion limited in streneous exercise. What another gas is diffusion limited? why?

Answer 1

high intensity exercise -> increased blood flow
-> because blood pass through pulmonary capillaries so quickly, there is not enough time to diffuse all oxygen in alveoli

Carbon monoxide: too high affinity to hemoglobin, not undergoing rapid gas exchange

Question 2

Cyanide toxicity

• characteristic breath?
• acid/base balance?

Answer 2

• almond breath odor
• metabolic acidosis: cyanide shuts down cytochrome C, making us relying on anaerobic metabolism (not oxidative phosphorylation) -> lactic acid accumulation

Question 3

DLCO in Goodpasture?

Answer 3

Goodpasture leads to interstitial fibrosis, so it is easy to think that DLCO will decreased.

However, due to intra-alveloi hemorrhage (how hemoptysis develops), DLCO increases

Question 4

How to treat

• methemoglobinemia
• cyanide intoxication
• CO intoxication

Answer 4

• methemoglobinemia: vitamin C or methelyene blue
• cyanide intoxication: nitrite followed by thiosulfate
• nitrite: inducing methemoglobin, which has high affinity to cyanide, sequestering cyanide from cells
• thiosulfate: cyanide -> thiocyanide (detoxified) by donating sulfur group
• CO intoxication: 100% hyperbaric O2
• High O2 can push out CO in Hb

Question 5

Effect of carboxyhemoglobin in Hb oxygenation curve

: left shift or right shit or no change? explain

Answer 5

carboxyhemoglobin

-> CO binds to Hb very tightly -> ALLOSTERIC CHANGE -> decrease O2 unloading -> left shit

Question 6

How does tension pneumothorax affect JVD?

Answer 6

distended JVD due to compression of SVC by air pressure

Question 7

Emergency. Signs of cerebral edema and elevated ICP. what is the first thing to do?

Answer 7

intubation and hyperventilation

• hyperventilation -> decreased pCO2 -> vasoconstriction
• > decreased cerebral blood flow -> reduce ICP

*also hyperventilation provides O2 and increased ICP may compress respiratory center in medulla

Question 8

Three drugs that cause methemoglobinemia?

Answer 8

• dapsone
• sulfanomide
• benzocaine

Question 9

What is the most common lung cancer that presents as pancoast tumor

Answer 9

squamous cell carcinoma

• this is surprising: squamous cell carcinoma usually presents in center…

Question 10

pancoast tumor presentation: ipsilateral or contralateral?

Answer 10

IPSILATERAL

left mass -> left ptosis
right mass -> right ptosis

*sympathetic chain does NOT decussates