blood gas metrics
- pH
- PaCO2
- PaO2
- HCO-3
- ABE
- Na+
- K+
- Cl-
- Proteins
blood gas values???????
- pH: 7.4
- PaCO2: 40 mm Hg
- PaO2: 90-600 mm Hg
- HCO-3: 24 mEq/L
- ABE: -4 - +4 mEq/L
- Na+: 140 mEq/L
- K+: 4 mEq/L
- Cl-: 100 mEq/L
- Totalprotein: 65g/L
Henderson-Hasselbalch equation use
– Estimates pH and base excess/deficit
– Defines magnitude of change but not the cause
- Base excess/deficit: what does it tell us?
– any difference that exists from the normal value
for bicarbonate
– Reflects non volatile acid changes (metabolic)
what is a buffer and what are examples in the body
- Buffer: substance that prevents extreme changes in the free concentration of H+ within a solution
– Hemoglobin (good for transporting CO2 from tissue to lung)
– NaHCO3 (most important)
– Phosphate
– Protein
how is CO2 transported in the blood?
– Dissolved and H2CO3: 7%
– HCO-3: 80%
– CarbaminoHb: 13%
cation is + or -? anion?
– Cation (+)
– Anion (-)
acid vs base role wrt h+
- Acid: donates H+ to solutions
- Base: removes H+ from solutions
what does a gamblegram show?
a graphical representation of the concentration of plasma cations (mainly Na+ and K+) and plasma anions (mainly Cl-, HCO3- and A-, also lactate).
-there are anions that are not routinely measured = unmeased anions (UA)
– Therefore, there is a deficit of anions in the gamblegram
metabolic acidosis is caused by:
- Acids from tissue metabolism
-Unmeasured anions (ketoacids, organic acids)
-Lactic acid - Hyperchloremia
- Combination of the two
three independent variables in quatitative/stewarts method? what do they determine?
– PaCO2
– SID
* Strong ion difference
– Weak acids (Atot)
* Proteins in blood
what is the strong ion difference? how do we calculate it, what is a normal value, and what do other values tell us?
- (Na++K+)-Cl- =44
- Metabolic acidosis: < 44
- Metabolic alkalosis: > 44
what usually decreases the value of SID?
increase in Cl-
what is the anion gap? what is the normal value and what do differing values mean?
- (Na+ + K+) – (Cl- + HCO-3)= 20
- Metabolic acidosis: > 20
- Metabolic alkalosis: < 20
effects of proteins on anion gap and acidosis/alkalosis
- Affect anion gap
- Proteins act as weak acids
– Hyperproteinemia = metabolic acidosis
– Hypoproteinemia = metabolic alkalosis
what substances are weak ions/buffers? what state do they exist in?
- Only partially dissociated
– Proteins
– Hemoglobin
what is SIG vs SID? how do we calculate SIG and what does this allow us to do?
strong ion gap vs strong ion difference
-corrects anion gap for proteins
- Corrects Anion gap for proteins:
– SIG = AG – (Total proteins x 0.25) - This calculation allows to determine the unmeasured anions (UA)
