Acid Base Flashcards
what does the henderson-hasselbalch equation estimate and define?
– Estimates pH and base excess/deficit
– Defines magnitude of change but not the cause
A ____ CO2 will result in a _____ HCO3- and vice versa
high; high
what are normal values for pH, PaCO2 and HCO3-
pH 7.4
PaCO2 40 mm Hg
HCO-3 24 mEq/L
what are some contributions to H+
– H2CO3
– Inorganic acid
– Organic acid
– Lactic acid
– Ketoacid
what is the solubility of CO2
0.03
what is a base excess/deficit
– any difference that exists from the normal value for bicarbonate
– Reflects non volatile acid changes (metabolic)
what is a buffer and what are some examples
Buffer: substance that prevents extreme changes in the free concentration of H + within a solution
– Hemoglobin
– NaHCO3
– Phosphate
– Protein
what is an ion
Ion: dissociated solute
– Cation (+)
– Anion (-)
behaviour of an acid vs a base in terms of H+
- Acid: donates H + from solutions
- Base: removes H+ from solutions
what does electroneutrality establish
Establishes that there has to be equal
amounts of cations and anions
what are unmeasured anions
- There are anions that are not routinely measured- Unmeasured anions (UA)
– Phosphate, Sulphate, organic acids (lactic acid), ketoacids, ± proteins
what is happening:
-low pH
-low PaCO2
-low ABE
metabolic acidosis
what is happening:
-low pH
-high PaCO2
-normal ABE
respiratory acidosis
what is happening:
-high pH
-low PaCO2
-normal ABE
respiratory alkalosis
what is happening:
-high pH
-low PaCO2
-high ABE
metabolic alkalosis
what is the formula to calculate CO2 for metabolic acidosis
CO2 = 1.5 (HCO-3) + 8
what is the formula to calculate CO2 for metabolic alkalosis
CO2 = 0.9 (HCO-3) + 9
what is the formula to calculate CO2 for respiratory acidosis
For every 10 mmHg increase in CO2 = (HCO-3) increases 1.3 units
what is the formula to calculate CO2 for respiratory alkalosis
For every 10 mmHg decrease in CO2 =(HCO-3) decreases 2-3 units
what are the three independent variables for quantitative/stewarts method to determine blood pH
– PaCO 2
– SID; Strong ion difference
– Weak acids (Atot); Proteins in blood
what does a SID of <44 indicate
metabolic acidosis
what does a SID of >44 indicate
metabolic alkalosis
how do you calculate SID
(Na+ + K+ ) - Cl- = ?
how do you calculate anion gap
(Na+ + K+ ) – (Cl- + HCO -3) = ?
