Acid Base balance Flashcards
what are the equations for pH?
- pH= pKa + log10 ([base]/[acid])
- pH= -log10[H+]
- pH= log10 1/[H+]
what is the definition for standard bicarbonate measured on ABG?
Calculation of bicarbonate concentration under standard conditions for example in plasma of fully oxygenated blood which has been equilibrated to a partial CO2 of 5.32 at 37 degrees
what is ‘base excess’?
The calculated amount of strong acid (mmol/L) which would have been added to one litre of the patients blood to reach a pH or 7.4 at a pCO2 of 7.4 at 37 degrees in alkalosis
what is ‘base deficit’?
The calculated amount of strong alkali (mmol/L) which would have been added to one litre of the patients blood to reach a pH of 7.4 at a pCO2 of 5.32 at 37 degrees
what is osmolality?
An estimation of the osmolar concentration of plasma and is proportional to the number of particles per kg of solvent.
what is the definition of osmolarity?
An estimation of the osmolar concentration of plasma and is proportional to the number of particles per L of solution
what is the equation for calculated osmolality?
2 x [Na] + Urea + Glucose
what is the osmolal gap?
Measured osmolality - calculated osmolality
what is the normal range for osmolal gap?
less than 10mmol/L
what is the equation for anion gap?
([Na] + [K+]) - ([HCO3-] +Cl-])
what is the normal range for anion gaps?
10-18mmol/L
what causes an anion gap?
un-measured anions such as albumin, phosphate, sulphate, lactate.
what does an albumin of 40g/L normally contribute to a negative charge causing an anion gap?
10mmol/L
if albumin levels reduce what happens to the anion gap?
it will also reduce
how long does respiratory compensation take to occur?
It occurs very rapidly
what is kussmaul breathing?
A type of respiratory compensation in response to acidosis. very deep breathing
how long does metabolic compensation normally take to occur?
36-72 hours
why does metabolic transcription take so much longer to occur?
It requires enzyme induction for increased genetic transcription or translation to occur.
how is bicarbonate produced in the tubular cell?
water + carbon dioxide = hydrogen bicarbonate
hydrogen bicarbonate with carbonic anhydrase makes it break down to hydrogen and bicarbonate ions.
how is the hydrogen from the breakdown of carbonic acid removed from the tubular cell?
It goes into a sodium hydrogen ATPase, this stops the potassium sodium ATPase pump meaning potassium will build up in the cell
what normally happens to the potassium levels in acidosis?
increase due to removal of hydrogen from the tubular cell
HYPERKALAMIA
