#clinical_tips
The importance of blood bicarbonate in metabolic acidosis
Buffers maintain the pH of the blood at about 7.4
Excess acid production by the cells leads to acidification of the blood
In this condition, the concentration of H+ is buffered by the following buffers.
Bicarbonate
hemoglobin
Phosphate
Due to the use of bases in the buffering process, blood pH will drop.
If all the bases are consumed, the buffering capacity will lose its efficiency and the pH will decrease rapidly.
In order to determine the base or acid status of the patient, it is necessary to measure the concentration of bicarbonate and carbon dioxide and blood pH through clinical tests.
In metabolic acidosis, when the blood pH reaches less than 7.35, it is very important to measure the pH and evaluate the amount of residual bicarbonate in order to buffer the acid that is continuously produced.
Having the values of these two variables, we can calculate the value of the third unknown variable through the Henderson-Hasselbach equation
Well, for a better understanding, join us to examine a question together
The results of the blood test of a patient suffering from acidosis are as follows
pH = 7.03
[CO2] = 1.1 mM
Note that the normal values of these two quantities along with bicarbonate are as follows
pH = 7.04
[CO2] = 1.2 mM
[HCO3-] = 24 mM
Now the question is, what is the amount of bicarbonate in this patient’s blood, and how much natural bicarbonate is used in buffering the disease-causing acid?
Well, to solve such a question, we have to do the following steps
1⃣ Write the Henderson-Hasselbach equation as follows
pH = pKa+ log ([HCO3-]/[CO2])
Note that (PKa = 6.1 bicarbonate).
2 Now we replace the given values in the equation.
7.03 = 6.1+ Log([HCO3-]/1.1) = 0.93 Log([HCO3-]/[1/10mM])
The antilogarithm of 0.93 is equal to 8.5. Therefore
8.5 = ([HCO3-]/[1.1mM])
And finally, the remaining amount of bicarbonate in the blood is equal to 9.4.
3. Now, by comparing this number with the normal amount of bicarbonate, we find that this patient has a decrease of 14.6 mmol of bicarbonate per liter of blood.
If the amount of bicarbonate drop is more than this value, this buffering system cannot buffer the excess amounts of acid and the result
Increased acid
pH reduction
And the patient’s life will be endangered.
This post is written by jm30303030