bikarbonat açığı

 

Bikarbonat Açığı :

 

If the bicarbonate distribution space could be determined, then the quantity of bicarbonate required to elevate the serum bicarbonate concentration by any given amount can be estimated from the bicarbonate deficit:

 HCO₃ deficit  =  HCO₃ space  x  HCO₃ deficit per liter

When the serum bicarbonate concentration is normal or only moderately reduced, the apparent bicarbonate space is approximately 55 percent of lean body weight. Thus, in a healthy 70 kg individual, the infusion of one vial of 8.4 percent sodyum bikarbonat will raise the serum bicarbonate concentration by approximately 1.5 mEq/L.

However, for a number of complex reasons related to the body's bicarbonate buffering mechanisms, and because the bicarbonate-carbon dioxide acid-base pair is an "open" system (ie, carbon dioxide can be added or removed in great quantities through ventilation), the bicarbonate space is not fixed; rather, it varies markedly with the initial bicarbonate concentration and the size and potency of the other buffer pools with which it equilibrates. When severe metabolic acidosis exists, the apparent bicarbonate buffer space enlarges markedly, reaching approximately 70 percent of lean body weight when the serum bicarbonate falls below 10 mEq/L and exceeding total body weight when the serum bicarbonate falls below 5 mEq/L