robin082006
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C is better choice
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| nadiabarati
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A
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| sridevibandaru24
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A
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| robin082006
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This Patient has signs of decreased CO2 due to altitude (decreased atmospheric pressure). (Central Apnea). The patient also has decreased O2 but this cannot lead to central apnea.
Extreme decrease in CO2 leads to the inactivation of the pulmonary stimulation system in brain. In treatment, we need increase CO2.
Kaplan says that in the serious case of decreased CO2, let the patient breath with high CO2 mix (breath in and out in a balloon). So C is better choice.
A seems to be the best at the first sign but it cannot reactivate the pulmonary system.
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| robin082006
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Remember that O2, Co2, N2 concentration are normal in high areas. Only atmosperic pressure is decreased. So the patient breath in hyperbaric N2 in order to increase inspiratory air pressure--> blood O2 content will be improved.
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| rman
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Robin, great reasoning. but i'm confused by the question stem. wouldn't increase in altitude cause HYPERventilation??
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| robin082006
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Yes, increase in altitude causes hyperventication.
But Acute extreme decrease in CO2, as in this case, inhibits respiratory center.
We need to reactivate respiratory center first by increasing CO2.
This is Central Apnea due to decreased CO2.
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| mitty
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I found the q in another forum.And the poster doesn't know the right answer.
My answer is A
The patient was living below see level for long time.i.e he was in hyperbaric enviroment where the partial pressure of O2 and N2 increase in the alveloli and body compartement.By suddenly going to high altitude he will develop sudden decompression which lead to bubbles of nitrogen emboli in the blood stream and tissue.(bends /caisson disease)
The trement is recomperession,i.e giving hyperbaric O2 mixed with nitrogen,followed by a slow and gradual decompression.(kaplan physiology pp 272)
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| docswapna
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i think C is right bcos we require to increase PC02 to stimulate the chemoreceptors (make the pt breathe into a paper bag)
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| cathy1
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It should be answer A. Normally you hyperventilate at high altitude this man HYPOventilate that means there is no chance of getting the O2 needed, he is severely hypoxic. Kaplan book says going to high altitude main drive ventilation change from co2 drive to 02 drive on perpheral chomoreceptors. Getting O2 in this man must be the most important thing without O2 brain damage. Bends or no bends. Its sort of a no win no win situation I think one must try to do the best possible wich not always is the optimal answer A.
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| aim
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A looks more reasonable, not sure
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| ssrpk
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i agree with Robin, think of it this way! PCO2 is very low in this patient, low enuff to cause HYPOVENTILATION....but still there must be high level of activating signals from peripheral chemoreceptors due to low PO2, right![however largely superseded by dangerously low level of PCO2] so wht ever ventilation is left, its due to low PO2, if we increase the PO2, then the only source of ventilation will be abolished, and the patient may go into total apnea! [ the same reason why we don't give high O2, to patients with COPD with resp.acidosis] this is just another extreme!
answer is definitely C.
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| fox
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The very reason for the hypoventilation of the patient must have been initial hyperventilation (as occurs in everybody in high altitude) & when u hyperventilate, u blow off ur Co2 & thus abolish ur respiratory drive. Hence C seems to be more logical...ie bring back the co2 to get back the resp drive.
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