Metabolic Acidosis Vs Alkalosis

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Bases: Have a higher affinity for protons than water and easily acquire protons in aqueous solution. charged (+1) when protonated (Acids uncharged) uncharged when de-protonated (Acids -1 charge) Most common biological weak base is the amino group, -NH2 Despite the differences between acids and bases the pKa concept can be used to quantitate the relative strength of amino groups. Notice: pKa values for carboxylic acid are less than < 7, pka values for amino groups are >7 (usually 9-11) i.e. a simple biologically important 10 amine, ethanolamine, pKa = 9.5 or choline, a quaternary (40) amine, pKa = 13.9 Choline is a good compound for systems in which a permanent positive charge is desirable, i.e. membranes (hydrophilic head groups) Phosphatidylcholine (lecithin) a key amphiphilic compound in biological membranes Buffering: At or near their pKa both weak acids and weak bases will resist changes in pH, thus acting as buffers Buffering is very important in biological systems, for rapid pH changes have disastrous consequences. The buffering capacity of ethanolamine and acetic acid occur well outside of the pH range normally seen in human blood (pH 7.35-7.45). Thus, other ionizable compou Continue reading >>

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  1. sonias

    3 This is my topic for this week in nursing school, respiratory & metabolic acidosis/ alkalosis. I am having trouble breaking it down. Can someone please help me understand this please? Any and all help is greatly appreciated.

  2. Esme12

    Normal values:
    PH = 7.35 - 7.45
    C02 = 35 - 45
    HC03 = 21-26
    Respiratory acidosis = low ph and high C02
    hypoventilation (eg: COPD, narcs or sedatives, atelectasis)
    *Compensated by metabolic alkalosis (increased HC03)
    For example:
    ph 7.20 C02 60 HC03 24 (uncompensated respiratory acidosis)
    ph 7.33 C02 55 HC03 29 (partially compensated respiratory acidosis)
    ph 7.37 C02 60 HC03 37 (compensated respiratory acidosis)
    Respiratory alkalosis : high ph and low C02
    hyperventilation (eg: anxiety, PE, pain, sepsis, brain injury)
    *Compensated by metabolic acidosis (decreased HC03)
    ph 7.51 C02 26 HC03 25 (uncompensated respiratory alkalosis)
    ph 7.47 C02 32 HC03 20 (partially compensated respiratory alkalosis)
    ph 7.43 C02 30 HC03 19 (compensated respiratory alkalosis)
    Metabolic acidosis : low ph and low HC03
    diabetic ketoacidosis, starvation, severe diarrhea
    *Compensated by respiratory alkalosis (decreased C02)
    ph 7.23 C02 36 HC03 14 (uncompensated metabolic acidosis)
    ph 7.31 C02 30 HC03 17 (partially compensated metabolic acidosis)
    ph 7.38 C02 26 HC03 20 (compensated metabolic acidosis)
    Metabloic alkalosis = high ph and high HC03
    severe vomiting, potassium deficit, diuretics
    *Compensated by respiratory acidosis (increased C02)
    ph 7.54 C02 44 HC03 29 (uncompensated metabolic alkalosis)
    ph 7.50 C02 49 HC03 32 (partially compensated metabolic alkalosis)
    ph 7.44 C02 52 HC02 35 (compensated metabolic alkalosis)
    *Remember that compensation corrects the ph.
    Now a simple way to remember this......
    CO2 = acid, makes things acidic
    HCO3 = base, makes things alkalotic
    Remember ROME
    Ok always look at the pH first...
    pH<7.35 = acidosis
    pH>7.45 = alkalosis
    Then, if the CO2 is high or low, then it is respiratory...If the HCO3 is high or low then it is metabolic. How you remember that is that the respiratory system is involved with CO2 (blowing air off or slowing RR), and the kidneys (metabolic) are involved with HCO3 (excreting or not excreting).
    Here is how you think thru it: pH = 7.25 CO2 = 40 HCO3 = 17
    Ok, first, the pH is low so think acidosis. CO2 is WNL. HCO3 is low. Draw arrows if it helps. The abnormal values are both low (think Equal). Metabolic imbalances are equal. So, this must be metabolic acidosis!
    Now, for compensation...If you have a metabolic imbalance, the respiratory system is going to try to compensate. Respiratory = CO2. If the CO2 is normal in the ABG, then there is no compensation going on. Compensation in acidosis will decrease the CO2 because you want to get rid of the acid (CO2). In alkalosis, it will increase because you want to add more acid (CO2)
    If you have a respiratory imbalance, the kidneys will try to compensate. Kidneys = HCO3. If the HCO3 is normal in the ABG, then there is no compensation going on. Compensation in acidosis will increase HCO3 because you want to hold on to the base to make it more alkalotic. In alkalosis, it will decrease because you want to excrete the base to make it more acidic.

  3. Esme12

    Check out this tutorial
    Interactive Online ABG's acid base

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