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  #1  
Old 09-06-2014
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Default Pathology question for the day!

A 30-year-old man presents to the emergency department complaining of shortness of breath, dizziness, nausea, and vomiting. He also says that his heart feels "like it is jumping out of my chest." Two days ago, he passed a burning house and stopped to help the residents evacuate. He reports inhaling a significant amount of smoke, but declined medical assistance at the scene because he had no symptoms. The patient reports feeling very fatigued the day prior to presentation and stayed in bed for most of the day. On physical examination, his pulse is 90/min, blood pressure is 100/60 mm Hg, and respiratory rate is 30/min with deep, gasping respirations. The rest of the examination is unremarkable with the exception of bright red vessels in both of his eyes and a smell of bitter almonds on his breath.
What is the mechanism of action of the toxic agent that resulted in this patient's symptoms?


A. Decreased blood oxygen-carrying capacity
B. Direct tissue injury
C. Inhibition of acetylcholinesterase
D. Inhibition of cellular respiration
E. Ribosome inhibition
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Old 09-06-2014
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Idea!

Option D.
(Cyanide poisoning)
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Hx of passing by burning house and bitter almonds breath.
Its Cyanide poisoning.
I would go with option A decrease blood oxygen carrying capacity. Oxygen in arterial blood decreases and oxygen delivery to the peripheral tissues also decreases as more cyanide binds with Hb
which also causes leftward oxygen binding curve!!
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Old 09-06-2014
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A?
Carbon monoxide poisoning.
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Old 09-06-2014
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More answers guys!
It becoming interesting. I got it wrong anyway!
It looks easy but tricky.
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Old 09-06-2014
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My mind confuse me with option D too It could be D too
Tell us answer

Last edited by Dr.ann; 09-06-2014 at 11:29 AM.
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Old 09-06-2014
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It's D ...

Bitter Almond smell of the breath - is the Key!
CN poisoning- Blocking Complex IV in Oxidative Phosphorylation Pathway
After inhibition of Complex IV O2 consumption is prevented which is the cause of the symptoms above...

Decreased blood oxygen-carrying capacity (choice A) is suitable for CO poisoning, as it has high affinity for heme groups, along with Complex IV inhibiton... cherry-red discoloration of the skin is key feature in this case, which is not mentioned..
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Last edited by MananaMD; 09-06-2014 at 12:29 PM.
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Old 09-06-2014
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Ok guys!

The correct answer is D.
Cyanide is a very toxic compound that can be formed in the high-temperature combustion of many materials, such as polyurethane, acrylonitrile, nylon, wool, and cotton, thus making cyanide poisoning common in the setting of smoke inhalation. The most common cause of cyanide poisoning in industrialized countries is household fires. Cyanide modifies the iron within cytochrome oxidase (cytochrome aa3) in the mitochondria, thereby abnormally interrupting the electron transport chain and halting cellular respiration. Tissues with the highest oxygen demands, such as the heart, brain, and liver, are most significantly affected because cyanide prevents oxygen from binding to cytochrome oxidase and serving as the final electron acceptor in the chain. On physical examination the retinal arteries and veins are bright red due to absent tissue oxygen extraction. Additionally, in some patients there is a smell of bitter almonds on the breath. These findings are not present with carbon monoxide inhalation, the other common toxin associated with smoke inhalation. Treatment includes induction of methemoglobinemia with a nitrite, then administration of a sulfate.
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Quote:
Originally Posted by Dr.ann View Post
My mind confuse me with option D too It could be D too
Tell us answer
The job of multi step reasoning always kills us wen we get the final step wrong like in ur case!
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Hooo i was soo stupid i knew the explanation. Well my bad!
These Qs gona kill us guys
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Quote:
Originally Posted by Dr.ann View Post
Hooo i was soo stupid i knew the explanation. Well my bad!
These Qs gona kill us guys
No, u are not!!!
I'd say we have to search for the clue word/key word in a question that might seem so long, detailed and tricky..choose and go, First choice is correct for the most of the questions.
If you think that they are trying to trick you, you end up over thinking the question and getting it wrong
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Quote:
Originally Posted by MananaMD View Post
No, u are not!!!
I'd say we have to search for the clue word/key word in a question that might seem so long, detailed and tricky..choose and go, First choice is correct for the most of the questions.
If you think that they are trying to trick you, you end up over thinking the question and getting it wrong
Yeah thats true whatever we pick up on first try its usually right..happens to me a lot lol
Well I just pray we all make through it smoothly! Good luck to all
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