Base Excess.
The Base excess is a measure of how radically deviated the metabolic system is. The base excess (BE) normal value is between -2 to +2 ( some texts site -3 - +3).
It is loosely influenced by bicarbonate (base or alkali). Many authors suggest that BE is the better value used to determine metabolic acidosis or alkalosis. One colleague of mine in the #FOAMed world (Chris Nickson who writes for "Life in the Fast Lane") states that
"Bicarbonate levels are not an ideal indicator of either metabolic or respiratory components of acid-base disturbance because it is affected by both.
Furthermore the relationship between metabolic acidosis and bicarbonate is neither consistent nor linear."
This essentially means that the more acidotic a person is, the bicarb does not necessarily change in a predictable way. And I agree. But it is nonetheless an indicator as to whether the acidosis is respiratory or metabolic.
Unlike pH or CO2, the concentration of the bicarbonate ion (HCO3-) (in mEq/L) is not measured, it is calculated from the PCO2 and pH.
As more less bicarb is excreted, the BE swings further into negative ( less than -3. Eg -5 or -7). The opposite occurs with accumulation of bicarb (base). The more there is, the more positive will be the BE. (>+3)
There it is BE or HCO3- for me Bicarb is quick and easy and does the job. But BE could be used as a well accepted alternative.
And that is Blood gases in 6 easy posts. I do teach these in a face to face workshop, and if you are interested in a respiratory seminar including ABGs in your town, let me know. I travel anywhere for 10 or more.
What's our next topic?
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