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Old 08-25-2012
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Default What changes in ABG in first minutes after PE?

A mildly obese 36-year-old woman travels from London to Tokyo on a long overnight flight. Seven hours into the flight, a blood clot from a deep vein thrombosis occludes her left pulmonary artery. Assuming that no change in ventilation occurs, what blood gas abnormality would develop in the first few minutes?

a) Decreased Paco2
b) Decreased Pao2
c) Increased Paco2
d) Increased Pao2
e) No change in Pao2 or Paco2

Along with your answer please give brief explanation. Thanks
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Old 08-25-2012
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i think it's b) pao2 decreased
paco2 remains constant i guess
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Old 08-25-2012
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I'm not sure but I think is C

theres a V/Q mismatch due to blood flow obstruction, no perfusion but same (normal) ventilation, increase physiologic dead space and retention of CO2

what's the correct answer??
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Quote:
Originally Posted by venky2600 View Post
i think it's b) pao2 decreased
paco2 remains constant i guess
i hope embolization causes increase in perfusion heterogeneity...fall in correlation between ventilation and perfusion(v/q mismatch)..the majority of changes in mismatch is due to perfusion changes..perfusion redistribution without compensatory changes in ventilation is responsible for hypoxemia..

in normal spontaneously breathing human,the normal response to pulmonary embolism is hyperventilation(decreased arterial co2 tension)..this lead to increase in already decreased v/q ratio and minimizing hypoxemia........
so, i'm stuck with b.....
need answer with explanation....!

Last edited by venky2600; 08-25-2012 at 01:29 PM.
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Old 08-25-2012
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Quote:
Originally Posted by debs View Post
I'm not sure but I think is C

theres a V/Q mismatch due to blood flow obstruction, no perfusion but same (normal) ventilation, increase physiologic dead space and retention of CO2

what's the correct answer??
Agree
If ventilation rate remains same co2 should increase
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Quote:
Originally Posted by MedicalExaminer View Post
Agree
If ventilation rate remains same co2 should increase
i'm not sure but i'm thinking that in embolization and in normal ventilation condition......ventilation is ggod but can't perfuse due to embolization....so, V/Q ratios will be high or infinite( as perfusion< ventilation) inembolized areas
and also severely decreased V/Q ratios in non occluded areas...so, redistribution takes place to non occluded vessels and resulting in impaired gas exchange.....hypoxemai will result...
for this response body compensates by hyperventilation and hypocapnia is also seen eventually......
actually i never learnt about hypercapnia in embolism ever before..so i'm asking like this...
correct me if i'm wrong...
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Old 08-26-2012
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I would go with b. dec pao2

reason for chosing b is , in any v/q issues , p02 gets messed up more compared to pco2 due to its poor poor diffusing capacity compared to co2..
If embolus was so massive to cause increased pco2 then it must be associated with decreased po2 also .. in this case as only left pulm artery is blocked, po2 will decrese first , then slowly pco2 tends to increase , stimulating the respiratory centers causing hyperventilation as a compensatory change.......
correct me if am wrong ...
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Old 08-27-2012
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Casandra what's the correct answer ?????
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Old 08-27-2012
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Default correct answer

The answer is c) Increased Paco2

I asked you guys for an explanation/discussion bc the official explanation didn't say anything.
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Old 08-27-2012
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Quote:
Originally Posted by Casandra View Post
The answer is c) Increased Paco2

I asked you guys for an explanation/discussion bc the official explanation didn't say anything.
oh ok well know with those explanation I'm confused :s
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