Why is the answer to this question Metabolic Alkalosis?

  1. 0
    Normal values:
    pH (7.35-7.45)
    pO2(90-100)
    pCO2 (35-45)
    HCO3(24-32)

    Question:
    What is this clients disorder?

    --> Client with an NG Tube has a pH of 7.50 (Alkalosis), pO2 90 (normal), PCO2 of 42 (normal) and HCO3 25 (normal)

    Answer: Metabolic Alkalosis.

    .
    ... I understand why it is alkalosis, but why is it metabolic if the HCO3 is in the normal range???

    Thanks.
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  3. 24 Comments so far...

  4. 2
    So, take a look at the labs. A long look. What do we know about metabolic syndromes -- be it alkalosis or acidosis? Is that it first goes through respiratory alkalosis/acidosis and is then advanced to metabolic syndrome. COMPENSATORY. The renal system is trying to fix the system by doing what it does best.

    You have a pH that is 7.50 -- this is high, KIND of near normal. You then have a PaCO2 that is nearing ABOVE normal levels. Then, you have the bicarbonate that is high but seems to be lowering. Your kidneys are excreting bicarbonate and your system is retaining the carbonic acid to try and normalize it.

    Look at the PO2...what does this look like? Hypoventilation. This patient is not breathing enough and is retaining CO2 -- ACID! However, hypoventilation is COMPENSATORY and will actually stimulate the action to breathe.

    Think to yourself when you look at the labs, "Ok. I know several of these labs are normal; however, many of the labs are nearing the high range or low range." What does this mean? Again! COMPENSATORY. The kidneys are long term compensatory systems.
    Last edit by Kuriin on Oct 3, '13
    arrie and RaiDade like this.
  5. 1
    I thought bicarb range was 22-26???

    So, your pH is alkalotic, your carbon dioxide is acidotic and your bicarb is alkalotic because it is closer to 26 than 22, hence why it is metabolic alkalosis. You werd using the incorrect range for your bicarb.
    KelRN215 likes this.
  6. 0
    Think about the scenario rather than the numbers. The only one you need to care about is 7.5, definitely alkalotic. What might the patient be losing if the tube in their stomach...hint hint...is set to suction. It's not bicarbonate on CO2 it's.......
  7. 0
    BTW, Nursing2102, remember that metabolic syndromes act together whereas respiratory act inversely. ^HCO3 and ^pH = Metabolic whereas ^pH and decreased PaCO2 = Respiratory.


    (or I guess you can use sarakjp's method...)
  8. 0
    PH is 7.50 -- alkalosis Question to ask: Is HCO3 high (metabolic) or CO2 low (respiratory)?

    Your HCO3 is on the low side, and CO2 on high side.... hmm, this is not metabolic alkalosis
    if it was, the HCO3 would have to be high or in normal range on the high side, this would mean it has been compensated

    Are you sure the numbers are correct?

    now that I see range for HCO3 is 22-26(!) )) it makes sense: HCO3 is in the upper corner, thus it's metabolic alkalosis(compensated).
  9. 0
    My professor told us the range for HCO3 is 24-32. My professor is also the same one that Nursing2102 has. We are confused because according to the ranges we were given, 24-32 bicarb, the example of HCO3 being 25 would be in the lower end..
  10. 0
    I would have the whole class to look it up and compare answers with the professor
  11. 0
    Quote from EP10
    My professor told us the range for HCO3 is 24-32. My professor is also the same one that Nursing2102 has. We are confused because according to the ranges we were given, 24-32 bicarb, the example of HCO3 being 25 would be in the lower end..
    You just answered the rationale, in your last sentence.

    Like StephenAndrews posted, you have to look at the ranges...if they are trending on the lower and higher end, the imbalance will be compensated; you must look at what is affected, as another poster stated, as well as the pH.
    Last edit by LadyFree28 on Oct 3, '13
  12. 0
    The professor's answer is that the condition is metabolic alkalosis secondary to gastric acid loss. It's confusing because the values are normal for all but the pH. No sign that there's any respiratory or metabolic issues aside from the alkalotic pH.


    The bicarb is on the lower end at 25, so low bicarb, How is that not nearing being acidic?


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