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#1
10-22-2011
 USMLE Forums Scout Steps History: Not yet Posts: 55 Threads: 21 Thanked 10 Times in 10 Posts
Calculate Myocardial Oxygen Consumption!

A 65-year-old man is hospitalized with severe chest pain. Various studies are done, including measurements of coronary blood flow and coronary sinus O2 content.

The values obtained are:
Coronary blood flow 50 mL/min per 100 g of heart
Arterial O2 content 19 mL O2/dL blood
Coronary venous O2 content 2 mL O2/dL blood

What is the myocardial O2 consumption per 100 g of cardiac muscle is (in mL O2/min)

(A) .12
(B) 8.5
(C) 9.5
(D) 200
(E) not calculable from these data
 The above post was thanked by: hiratamkeen (10-24-2011)

#2
10-22-2011
 USMLE Forums Master Steps History: 1+CK+CS+3 Posts: 1,353 Threads: 94 Thanked 873 Times in 506 Posts Reputation: 886

E) ...
At least that's what my calculatings skills and lazyness tell me =))
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#3
10-23-2011
 USMLE Forums Guru Steps History: 1 + CS Posts: 300 Threads: 22 Thanked 97 Times in 62 Posts Reputation: 107

Bbbbbbbbbbbbbbb
#4
10-24-2011
 USMLE Forums Scout Steps History: Not yet Posts: 55 Threads: 21 Thanked 10 Times in 10 Posts

#5
10-24-2011
 USMLE Forums Addict Steps History: Not yet Posts: 177 Threads: 25 Thanked 75 Times in 55 Posts Reputation: 87

What is the source of this question?
#6
10-24-2011
 USMLE Forums Scout Steps History: Step 1 Only Posts: 10 Threads: 1 Thanked 2 Times in 2 Posts Reputation: 12

i think the ans is B

because if we use the formula of the ficks principle where
flow=O2 consumption/A-V
we have the flow.and we have arterial(A) and venous(v) oxygen concentration so we can calculate the Oxygen(O2) uptake.
Atleast thats what i can think how we need to calculate
 The above post was thanked by: drhnis (10-25-2011)
#7
10-24-2011
 USMLE Forums Scout Steps History: Not yet Posts: 39 Threads: 6 Thanked 35 Times in 11 Posts Reputation: 45

B - is just calculation
#8
10-24-2011
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#9
10-24-2011
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i still dont understand how did u calculate the answer
#10
10-24-2011
 USMLE Forums Newbie Steps History: Not yet Posts: 5 Threads: 0 Thanked 5 Times in 1 Post Reputation: 15

Quote:
 Originally Posted by docnok A 65-year-old man is hospitalized with severe chest pain. Various studies are done, including measurements of coronary blood flow and coronary sinus O2 content. The values obtained are: Coronary blood flow 50 mL/min per 100 g of heart Arterial O2 content 19 mL O2/dL blood Coronary venous O2 content 2 mL O2/dL blood What is the myocardial O2 consumption per 100 g of cardiac muscle is (in mL O2/min) (A) .12 (B) 8.5 (C) 9.5 (D) 200 (E) not calculable from these data

The calculation formula is MVO2=(CaO2 -CvO2)XCBF
but first you should convert 19 and 2 per DL to Grams they will be 19/100=0.19 and 2/100=0.02 so then you will calculate easily , as1dl is 100 gram
(0.19 -0.02)x50=8.5
 The above post was thanked by: docnok (10-25-2011), DocSikorski (10-24-2011), Dr.Lacune (08-21-2012), dr.muhamad (10-25-2011), Learner (10-25-2011)

 Tags Cardiovascular-, Physiology-, Step-1-Questions

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