NBME 22 4 Months (NBME Answers)

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Retired NBME 22 Answers

nbme22/Block 2/Question#6 (reveal difficulty score)
A 52-year-old man is brought to the emergency ...
4 Months 🔍 / 📺 / 🌳 / 📖
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submitted by ∗welpdedelp(270)

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It was just asking the lifespan of RBCs (120 days)

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haliburton If I'm reading this right, this is just a tricky dicky question. I think CO binds 200x stronger than O2. But if an O2 cycles through binding / unbinding 200 times before a CO gets kicked off, this should still clear the CO from that cell sooner or later. strange to think it is 1. essentially permanently trapped in a cell, and 2. doesn't kill you and can be treated with O2 to resolution within a few hours or a day. They must just be thinking, until that last RBC dies, you've got original CO in a circulating cell. but just a fraction (because you didn't die). not sure how that CO isn't just passed on during recycling, based on this line of thinking. +8

link981 The question while stupidly written, asks how long the RBC's that carry the CO take to be removed from the circulation, not how long the CO takes to be removed from the RBC. Just asking the lifespan of RBCs in an stupidly complicated way. As we know, RBC's life span is about 120 days and then they are removed from our circulation. 120 days is about 4 months. Next time they will probably ask weeks or in hours, who knows? smh +12

baja_blast If that's what they're looking for why cant the NBME people just ask "How long does it take for RBCs to turn over?" Ridiculous. +2

xmen yOU HAVE TO VIGILANT !!!!!! BY THE WAY, I ANSWERED WRONG ALSO +

chaosawaits Perfect example of how I'm a smart dumbass here: I was smart enough to recognize that the question was asking about RBC lifespan. I was about to click 4 months, but then I saw that the carboxyhemoglobin concentration was 40%. I took 40% of 100 days to be 40 days, which is about a month. And that seemed totally logical to me at the time. FML +1

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submitted by iviax94(7)

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I figured they were trying to get at the life expectancy of an RBC, but wouldn’t supplemental O2 technically replace the CO bound to RBCs? FA even mentions that CO binds competitively to RBCs, and isn’t that the whole point of giving hyperbaric/100% O2?

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nc1992 First aid has a lot of errors +

yotsubato Thats not an error though. Thats the actual reason behind giving hyperbartic O2 for CO poisoning... +12

mumenrider4ever The question ask how long it takes to remove all the CO-carrying RBC so I think they're implying that theoretically not every single CO-carrying RBC would be replaced with oxygen from the supplemental O2 and some would die off naturally +2

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submitted by ∗link981(208)

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The question while stupidly written, asks how long the RBC's that carry the CO take to be removed from the circulation, not how long the CO takes to be removed from the RBC. Just asking the lifespan of RBCs in an stupidly complicated way. As we know, RBC's life span is about 120 days and then they are removed from our circulation. 120 days is about 4 months. Next time they will probably ask the RBC lifespan in weeks or in hours, who knows? smh

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submitted by ivypoison(6)

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Oxygen can compete CO to bind Hb but i think not all CO-Hb can be removed. Notice " ALL" the C0-binding RBC so go with CO-Hb RBC die. though i spent a lot of time for this question too

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