kiranmayi
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Features of mild carbon monoxide poisoning include:
A: decreased arterial PO2.
B: decreased hemoglobin-oxygen affinity.
C: increased alveolar ventilation.
D: decreased arterial O2 concentration.
E: all of the above.
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| krsma
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since u said mild, i'm guessing C? :?:
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| asmi
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B..since decreased oxygen saturation of Hb.
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| IT153
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would also say B since Hb is partially saturated with CO
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but doesnt CO shift the oxy-Hb curve to left,meaning that dec loading or affinity of O2.
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| kiranmayi
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D)…alveolar ventilation is not increased in mild co poisoning .HB-O2 WILL INCREASE BCOZ THE HB-O2 CURVE SHIFT TO LEFT
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It should be "B" . That's the good choice
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| krsma
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Choice B is not correct because there is an increase in the affinity of the hemoglobin for oxygen as evidenced by the leftward shift of the oxygen dissociation curve.
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is it A?...becos dissolved form will decrease as increase in hb bound form
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| dr_sarim
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hey!!
the shifting of the curve to right means decrease in affinity of hemoglobin..so that the oxygen is unloaded in the metabolically active tissues..in co poisoning, po2 will be normal (exclude A), only saturation of oxygen is decreased (sao2) as co has greater affinity(*200 times) for hemoglobin ,thus it displaces o2 from hemoglobin regardless of the fact that its in high or low concentration...the symptoms of co poisoning are not specific ,so i would exlude C also even though hyperventilation does occur with increasing toxicity...it leaves me with B or D.....frankly speaking i didnt understand what arterial o2 conc. means...(ABG's??..but that is a measure of partial pressures)...i would go for D
To,kiranmayi
can u explain D??please
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| dr_sarim
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its b
can anybody explain d?
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| doc179
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what is the difference between A and D? If two given choices on an exam mean the same thing, it can be neither choice.
I feel it is B. Without worrying about oxygen dissociation curves and just thinking casually, when CO binds Hb, the Hb is no longer interested in binding with O2. Does that not constitute "decreased affinity"?
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| cool_guyp4u
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dr_sarim wrote:
its b
can anybody explain d?
When the Hb - O2 association decreases, how is O2 transported? In Plasma. But, in plasma, O2 has less concentration.
Hence, Hb- O2 is reduced.
Plasma O2 is increased but not to the extent that it can make up for the Hb-O2 reduction.
So, eventually, O2 concentration is reduced.
B & D are correct.
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| general malaise
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answer is C. not A or D cause oxygen content doesn't decrease. not B cause CO causes Hemoglobin to increase affinity for oxygen. there is increased alveolar ventilation to attempt to compensate for tissue hypoxia
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| cool_guyp4u
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general malaise wrote:
answer is C. not A or D cause oxygen content doesn't decrease. not B cause CO causes Hemoglobin to increase affinity for oxygen. there is increased alveolar ventilation to attempt to compensate for tissue hypoxia
Ok. I did not refer to a textbook till now because I just posted what was in my mind. Now - that you have contradicted my statement, I am posting what Kaplan lectures notes and Kaplan video lecture says:
"In CO poisoning, Total O2 content is decreased, but the PaO2 is normal. Therefore, there is no ventilatory response to this hypoxia."
" In CO poisoning, arterial PO2 is normal, but oxygen saturation of Hb is depressed."
"CO Poisoning: PO2 - N, Hb conc - N, O2 per g Hb - reduced, O2 content - reduced."
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| aim
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B for sure but D may be
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| NE
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In CO posoning O2 affinity for Hb it's NOT decreased; CO has a greater affinity for Hb than O2 and this is why SaO2 is decreased. Therefore:
Total O2 content= PaO2+SaO2. Pa is NORMAL and SaO2 is decreased so arterial O2 will be decreased.
Anyway - symptoms tend to correlate well with the patient's peak blood carboxyhemoglobin levels. can begin
*Levels 10 to 20%- Headache and nausea
*> 20% - vague dizziness, generalized weakness, difficulty concentrating, and impaired judgment
* > 30% commonly cause dyspnea during exertion, chest pain (in patients with coronary artery disease), and confusion
*30-60%- cause syncope, seizures.
*> 60%-Hypotension, coma, respiratory failure, death
Attached Files:
RNA.jpg (38 KB, 4 downloads)
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| NE
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Sorry for the picture!
So I guess the answer is D.
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| ssrpk
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agrree with D
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| girl^interrupted
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It was a fairly easy question, very well explained by Prof.Dunn in his kaplan lectures.
a. decreased arterial PO2. CO NEVER decreses pO2, it remains 100mmHg or close (95)
b.decreased hemoglobin-oxygen affinity. CO shifts curve to the left so it INCREASES affinity
c. increased alveolar ventilation. CO has NO effect on alveolar ventilation because it has no effect on CO2 (major controller of ventilation at rest) or on PO2 (Hypoxia causes hyperventilation)
d. decreased arterial O2 concentration. CO DECREASES the O2 saturation i.e.SaO2 not PO2. So this is the answer..
I'll recommend doing kaplan physiology Q-bank saved questions. Some kind soul posted them up on another forum long time ago . 100 Qs on Resp...
AND not to b missed, prof.Dunn's lectures (kaplan)
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