fongch
Forum Elite
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This is a Q from Kaplan Qbook. I know the answer - so please provide your reasoning in your answer. I do NOT want spend 5 minute typing just to get a single letter reply.
A 71-year-old man with a long hisory of poorly controlled HT presents to ER w/ headache and visual changes. BP 220/130mmHg and an iv nitroprusside drip is started. Later in ICU his BP is 135/75mmHg but he became hypoxemic with room air saturation falling to 80%. The most likely reason for hypoxemia?
A Elevation of carboxyhemoglobin levels
B Elevation of methemoglobin levels
C Hypoventilatino
D Loss of hypoxic pulmonary vasoconstriction
E PE
Again, keep in mind that provide your reasoning in your answer.
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| dr.wad
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A_ nitroprusside cause thiocyanate poisoning >>>>> carboxyhemoglbin
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| Justice
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(A)
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Don't live in a town where there are no doctors
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| fongch
Forum Elite
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I was thinking B, since nitroprusside can increase the nitrate level in blood.
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| vradojc1
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I'd go with methemoglobinemia, but he has lowered P02 which is not seen there.
+ in cyanide poisoning you'd see the same - normal P02 since it is cellular toxin inhibiting cytochrome and it wouldn't affect hemoglobin.
+ he probably didn't receive dose high enough for both of the toxicities.
I don't know.
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| vradojc1
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What's wrong with me - methemoglobinemia is result of nitroprusside poisoning treatment. We don't have a clue about it.
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| snake0613
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i think d
because nitro- can magnify some arteies in lung,so cause the low oxgeny?
maybe
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| r_albayunen
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the answer for this ? is B - nitrates -> methahemoglobin, thats why for cyanide poisoning one of the tx is amyl nitrite to form cyanomethaHb ...
this is the cause of his hypoxemia.
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| vradojc1
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I checked qBook, answer is D and explanation is that since it causes pulmonary vasodilation, it causes V/Q mismatch because of disregulation of pulmonary blood flow autocontrol (more blood now goes to the less ventilated alveoli)
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