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-   -   The Hemoglobin Disocciation Curve After return of circulation (https://www.usmle-forums.com/usmle-step-1-forum/4690-hemoglobin-disocciation-curve-after-return-circulation.html)

 fin-84 11-03-2010 11:13 PM

The Hemoglobin Disocciation Curve After return of circulation

You are second year medical student and you have chance to volunteer as life guard in Hawaii. As you enjoy your time in there, you'll happen to see elderly, little obese gentleman to collapse in beach. Immediately you run to this gentleman and test for breathing and pulse. You manage to feel breathing and you get pulse from the carotid arteries. HR is about 60. When ambulance come to the scene you connect gentleman to the monitor. Almost immediately you see that patient went from sinusrhythm to asystole. You start cardiopulmonary resuscitation (CPR) and after 25 minutes you get return of spontaneous circulation (ROSC). If you could draw blood from the patient and analyse the dissociation curve of patients hemoglobin, you would propably see (compared to patients normal condition):

a) dissociation curve to move left
b) no changes
c) dissociation curve to move right
d) you wouldn't have any hemoglobin from patients RBCs

 step1an 11-04-2010 12:05 AM

c) dissociation curve to move right

This elderly gentleman was out for 25 minutes.... this would lead to acidosis which would cause right ward shifting of the oxygen dissociation curve.

 Pixie 11-04-2010 03:39 AM

B-no changes in curve

 varun.nat25 11-04-2010 05:12 AM

answer is c since due to no circulation of blood, there would be hypoxia and acidosis. thus more O2 ll be released from the Hb

 fin-84 11-04-2010 05:55 AM

The Bohr Effect

I think one major thing to learn in biochemistry is Hb dissociation curve and effect of pH, O2, CO2, BPG etc to it. In Lippincott's illustrated reviews: Biochemistry this thing is very profoundly taught.

In this question idea is the decreased pH (acidosis) which were caused by co2 accumulation and right shift of dissociation curve...

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