Acidosis & alkalosis: Difference between revisions

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===Metabolic acidosis===
===Metabolic acidosis===
Unfortunately, life as ever, is not so simple. There are two types of metabolic acidosis - with or without an '''anion gap'''. Essentially, this is the difference in concentrations between anions (+ve ions) and cations (-ve ions). (Na<sup>+</sup> + K<sup>+</sup>) - (Cl<sup>-</sup> + HCO<sub>3</sub><sup>-</sup>)
Unfortunately, life as ever, is not so simple. There are two types of metabolic acidosis - with or without an '''anion gap'''. Essentially, this is the difference in concentrations between cations (+ve ions) and anions (-ve ions). You calculate it using the following formula<br>
<br>
(Na<sup>+</sup> + K<sup>+</sup>) - (Cl<sup>-</sup> + HCO<sub>3</sub><sup>-</sup>)
 
===Metabolic alkalosis===
===Metabolic alkalosis===
===Respiratory acidosis===
===Respiratory acidosis===
===Respiratory alkalosis===
===Respiratory alkalosis===

Revision as of 12:11, 22 September 2009

Here is a glossary of these terms, which is useful for understanding some of the blood buffer systems. There are basically four abnormalities with regards to the acid-base balance in blood. You should ask yourself three questions:

  1. Is the pH high or low? - low pH= acidosis and high pH = alkalosis.
  2. Is CO2 abnormal? - if 'yes':
    1. Is this in keeping with the pH change? - i.e. when pH↑, CO2 OR pH↓, CO2. These changes point to a respiratory acidosis/alkalosis. If the change is not there, then it is a compensatory change.
  3. Is the HCO3- abnormal? - if 'yes'
    1. Is this change in keeping with the pH change? - i.e. (opposite to CO2 changes) when pH↑, HCO3- OR pH↓ HCO3- then the change is metabolic. Otherwise, the change is again a compensatory change.

"Compensatory" means that there is a change to the body's acid-base balance but the buffer systems the body has in place are attempting to deal with it. At the end of asking these questions you should end with one of five options. They are the titles the following titles

Metabolic acidosis

Unfortunately, life as ever, is not so simple. There are two types of metabolic acidosis - with or without an anion gap. Essentially, this is the difference in concentrations between cations (+ve ions) and anions (-ve ions). You calculate it using the following formula

(Na+ + K+) - (Cl- + HCO3-)

Metabolic alkalosis

Respiratory acidosis

Respiratory alkalosis