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Quick Reference

    Metabolic Acidosis
    Clinical Manifestations
    • hyperkalemia: shift of acid to ICF and K+ to the ECF
    • anorexia, nausea, and vomiting
    • warm, flushed skin
    • cardiac dysrhythmias & CNS dysfunction
    • headache, diarrhea, tremors

    Metabolic Alkalosis
    Clinical Manifestations
    • cardia dysrhythmias; seizures; confusion; muscle twitching, agitation
    • >pH;>HC03; normal PaCo2 or elevated if compensation occurs

    Respiratory Acidosis
    Clinical Manifestations
    • > PaCo2; HCO3 is normal or > with renal compensation
    • vasodilatation; cardiac dysrhythmias, tachycardia, somnolence, decreased ventilation

    Respiratory Alkalosis
    Clinical Manifestations
    • > pH; < PaC02; HCO3 normal or low due to compensation
    • nausea, vomiting, tingling of fingers
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Assessment :: Assessment Step 3 :: Compensation

    Step Three: Our bodies have compensatory mechanisms that assist us to return to a state of homeostasis (equilibrium). The body attempts to compensate for whatever the primary problem is in an effort to return the acid-base balance to normal. An illustration of COMPENSATION is given below:

      A newly diagnosed Type 1 diabetic client has a ‘primary’ problem of metabolic acidosis (pH 7.29; HCO3 16 mEq/L) due to an increase in ketone bodies (ketoacidosis). The nurse notes that the ABGs show a below normal PaCO2 value (27mmHg) and the client is breathing faster in an attempt to ‘blow off’ the carbon dioxide (CO2:’acid’) to create a respiratory alkalosis, the opposite of metabolic acidosis!

    Hint! In order to recognize ‘compensation’ look for a change in the buffering system that was not involved in the ‘primary’ problem.

    Example: If a client is demonstrating signs and symptoms of respiratory acidosis and the ABG results are something like: pH 7.27 and a PaCO2 of 58 mmHg and the body is compensating for this ‘primary’ abnormality, the other buffer system (primarily HCO3) will be changed (e.g. elevated HCO3: 30mEq/L).

    The convenience is that the ‘other buffer system’ change will be in the ‘same direction’ as the ‘primary problem.’ In this example the PaCO2 is elevated and the compensatory system (HCO3) is above the normal range. Consequently, they are both elevated! This tells you that the human body is compensating for the ‘primary problem!’

    Therefore, you were able to determine that there was an elevated PaCO2 (increase in acid or a respiratory acidosis) and an increased HCO3 (increased base or metabolic alkalosis). But you were able to determine respiratory acidosis as the ‘primary problem’ due to the pH being less than 7.35! This example illustrates a respiratory acidosis with a compensatory metabolic alkalosis. The opposite system will come to the rescue!

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