DrPak
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Toxic doses of apirin causes depression of the respiratory center leading to respiratory acidosis. In addition, interference with the Kreb's cycle and uncoupling of oxidative phosphorylation causes metabolic acidosis and hyperthermia (which I get due to Goljan). However it also leads to hypokalemia - why does that happen? I don't get it.
Also, chronic use of aspirin can cause hypoglycemia. Why is that?
I'm not testing anyone here... I don't know myself.
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| DrPak
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Also, how does toxic doses of aspirin cause vasomotor collapse?
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| mjl1717
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Ill attempt to answer the hypokalemia part:....As far as I know ASA causes 1st- metabolic alkalosis then 2nd respiratory acidosis. With the 1st metabolic component you automatically think "hypokalemic metabolic alkalosis". Hope this gives a little insight
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| anjushree
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i think salicylate first cause resp alkalosis so hypokalemia
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| mjl1717
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I must also admitt, I get the ph part of ASA confused at times.
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| oct
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Aspirin ( Salicylic acid) intoxication:
-Earliest manifestion: Respiratory Alkalosis ( affect Resp. center)
-Later: Metabolic Acidosis b/c it interfere w. certain metabolic process---> Accumulation of organic acids such as Lactic acid & ketoacid.The Salicylate itself makes up just a small part of acidosis.
(Fr. ridiculously simple books-chapter 7)
-----> Toxicity: u have normal PH (Goljan)
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| anjushree
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hypoglycemia---i think glucose may be used up due to inc metabolism ,,,salicylate being uncoupler inc metabolism
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| dr_rl
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if aspirin affects the respiratory center, then the first manifestation should be depression of the respiratory center ---- leading to decreased respiration - --- leading to retention of CO2------ leading to respiratory acidosis-----leading to METABOLIC ACIDOSIS and HYPERKALEMIA.
i am really confused here.
i dont get the logic behind either metabolic alkalosis or hypokalemia (both of which are present in toxic doses of aspirin!)
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| maoudoody
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at moderate doses aspirin causes mild incoupling of oxidative phophorylation..........>increase o2 demand...........> hyperventilation..........>resp alkalosis
resp alkalosis is corrected by the kidney by throwing bicarb and retaining H+
at toxic doses aspirin causes inhibition of the resp center so we know have - i mean the patient not we as doctors!!!! - resp and metabolic acidosis which is fatal and incompatible with life
now wat about hypokalemia
it is obviously that early alkalosis will cause hypokalemia due to redistribution of h+/k+ across the cell membrane to correct for alkalosis
late hypokalemia occurs due to the presence of high levels of unabsorbable anions " in this case salicylates" in the kidney tubules leading to high k loss in urine
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| dr_rl
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thanks maoudoody.
i looked into a few books and found out a few more things that would be relevant.
Aspirin (non toxic doses): Uncoupling of oxidative phosphorylation -------> increased oxygen demand ------> hyperventilation ------> resp alkalosis ---------> hyperkalemia with ongoing renal compensation (this part is pretty easy to see)
Aspirin (toxic doses): suppression of the resp center ---> decreased ventilation ------> CO2 retention --------> respiratory acidosis -------------> kidney tries to excrete H+ (but because we are talking of toxic doses here, acid excretion is NOT optimum) ---------> blood pH falls.
Now, toxic doses of aspirin also does 3 more things: (along with a host of others)
1. water retention
2. diarrhea
3. severe nauseaa ----> vomiting (which is more common than points 1 and 2)
all these tend to lower potassium. So we have respiratory acidosis and hypokalemia.
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| dkmj13
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Hi Dr Pak
As far as I know Aspirin causes respiratory alkalosis and metabolic acidosis.
The Hypokalemia is due to respiratory alkalosis, which causes left shift of the Hendersen Hasselbach equation and essentially causes decrease in H+ ions K+ is used instead of H+ in the collecting tubules.
Please let me know if this is satisfactory
dkmj13@yahoo.com
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| DR_K
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as aal of u have already explained everything i just want to add one thing that in case of toxic doses of aspirin ATP level decreases to an extended that neurons stop firing which cozes the depp of resp centre.
i know that alkalosis can coz hypokalemia which occurs in high therapeutic doses but not in toxic doses, the thing which is very confusing is that kaplan has mentioned hypokalemia under the heading of toxic doses of aspirin which is causing acidosis not alkalosis:S.
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