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NBME 23 Answers

nbme23/Block 1/Question#50

A 45-year-old woman with coronary artery disease ...

4.5

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 +4  upvote downvote
submitted by welpdedelp(103),

30* 0.15. Think about it, there is x flow with an oxygen concentration of y--so to find out the delivery you just multiply them together.

yotsubato  One of those questions too simple to believe its actually the right answer +13  
mimi21  Right, I was like this is too simple lol ! im not sure if this is also a good tip but I tend to look at the units they are asking for and double check my math to make sure I end up with them. +3  
osgood-schlatter  what equation is it exactly? +  
arcanumm  Literally did not even conceptualize this question, just looked at the units. +  




 +2  upvote downvote
submitted by nor16(18),

all those non maths guys here, dont skip these questions, try to arrange the units, here you´d easily find out that you just have to multiply! Give it a try :-)

charcot_bouchard  This was like Filtered Load ques of Renal. Where u multiply icoming fluid (GFR) with the desired substances conc (Px) so FIltered load of A is GFR x Pa Same here. Myocardial O2 supply is Blood flow x Conc of O2 in that blood flow +2  




 +2  upvote downvote
submitted by sam1(7),

What about the additional flow through the circumflex?

maddy1994  exactly man i got 4.5 and i thought he asked ventricle and left circumflex should be there so i put 5 ...glad someone thought like me.i was just cursing myself for over thinking. +3  
djtallahassee  Yea put 5 here too. they are essentially saying the myocardial oxygen supply to the left ventricle comes from the LAD. Not sure if true or not but figured that the LCX would at least contribute 20% of the blood +  




 +1  upvote downvote
submitted by guillo12(28),

Fick principle: CO= Rate of O2 consumption/arterivenous O2 concentration

CO means cardiac output or Flow of blood

charcot_bouchard  This wasnt Fick +1