Acid Base Flashcards
what does a blood gas analyzer measure
- pH
- PaCO2
- PaO2
- ABE
- K+
- Na+
- Cl-
- HCO3-
- proteins
what is a normal amount of TP in a herbivore/person
65 g/L
what is a normal range of ABE
-4 to 4 mEq/L
what is a normal amount of HCO3-
24
what equation is the traditional method of acid-base
Henderson-Hasselbach
what does the traditional method of acid-base estimate (2)
pH and base excess/deficit
Henderson-hasselbach defines _________ but not _________
magnitude of change; cause
what is the hydrolysis reaction
H20 + Co2 -> H2Co3 -> HCO3- + H+
what is the implication of the hydrolysis reaction
high Co2 causes high HCO3 and high HCO3 causes high CO2
what is H2Co3
Carbonic acid; volatile acid
what are examples of non-volatile (metabolic) acids
inorganic acid, organic acid, lactic acid, ketoacid
what is base excess/deficit? what does it reflect?
any difference from the normal range for HCO3 (-4 to 4)
reflects non-volatile (metabolic) acid changes
how do we calculate base excess/deficit
it is the deviation x 1.2
what is a buffer
substance that prevents extreme changes in the free concentration of H+ within solution
name 4 examples of buffers
- HCO3
- phosphate
- protein
- NaHCO3
during transport, what % of CO2 is dissolved? what % is transported as HCO3? what % is HbCO2NH2 (carbaminohemoglobin)
7% dissolves; 80% HCO3; 13% as HbCO2NH2
when CO2 is being bound to RBC/released from RBC, what balances the negative charge created through the formation of HCO3-
Cl- (either enters or leaves)
what is an ion? what are the 2 types
an ion is a dissociated solute: cations (+) and anions (-)
what does an acid do to solutions? what does a base do
acid donates H+; base removes H+
what are unmeasured anions
anions that are not routinely measured (aka ion gap)
what are examples of anions in the unmeasured anions category
phosphate, ketoacids, sulphate, organic acids, +/- proteins
what are the causes of metabolic acidosis
- hyperchloremia
- acids from tissue metabolism (lactic acid, unmeasured acids)
- combination of the two
how do we determine respiratory vs metabolic acidosis or alkylosis
changes in the ABE reflect METABOLIC; increased pH = alkylosis and increased pH = acidosis
respiratory acidosis = ________; respiratory alkylosis = ____________
increased PaCO2; decreased PaCO2
what formula do you use to determine if there is a respiratory component to metabolic acidosis:
for every 10mmHg decrease in CO2, HCO3- decreases 2-3 units
CO2 = 0.9 (HCO3-) + 9
CO2 = 1.5 (HCO3-) + 8
for every 10mmHg increase in CO2, HCO3- increases 1.3 units
CO2 = 1.5 (HCO3-) + 8
If value is within this range, there is no respiratory component
What formula do you use to determine if there is a respiratory component to metabolic alkylosis
for every 10mmHg decrease in CO2, HCO3- decreases 2-3 units
CO2 = 0.9 (HCO3-) + 9
CO2 = 1.5 (HCO3-) + 8
for every 10mmHg increase in CO2, HCO3- increases 1.3 units
CO2=0.9(HCO3-)+9
What formula do you use to determine if there is a metabolic component to respiratory acidosis
for every 10mmHg decrease in CO2, HCO3- decreases 2-3 units
CO2 = 0.9 (HCO3-) + 9
CO2 = 1.5 (HCO3-) + 8
for every 10mmHg increase in CO2, HCO3- increases 1.3 units
for every 10mmHg increase in CO2, HCO3- increases 1.3 units
What formula do you use to determine if there is a metabolic component to respiratory alkylosis
for every 10mmHg decrease in CO2, HCO3- decreases 2-3 units
CO2 = 0.9 (HCO3-) + 9
CO2 = 1.5 (HCO3-) + 8
for every 10mmHg increase in CO2, HCO3- increases 1.3 units
for every 10mmHg decrease in CO2, HCO3- decreases 2-3 units
what is another name for the quantitative method
Stewart’s method
according to Stewart’s method, what determines blood pH (3)
- PaCO2
- SID (strong ion difference)
- weak acids (proteins in blood)
how do we determines the SID
(Na+ + K+)-Cl-
what is a normal SID? what is metabolic acidosis? what is metabolic alkylosis
44 ; acidosis < 44; alkylosis > 44
T/F the concentrations of strong ions are not affected by other ions
T
how do we determine anion gap (AG)
= SID + HCO3
= (Na + K) - (Cl + HCO3)
what is a normal value for AG? what is metabolic acidosis? metabolic alkylosis?
20; acidosis > 20; alkylosis < 20
is SID or AG more reliable? why?
SID; AG includes HCO3- making it unreliable
what can make anion gap more reliable
proteins
proteins act as weak ______; thus, hypoproteinemia = ____________ and hyperproteinemia = _______________
acids; metabolic alkylosis; metabolic acidosis
how do we determine SIG
SIG = AG - (total proteins x 0.25)
= (SID + HCO3) - (total proteins x 0.25)
what does SIG allow us to determine
the unmeasured anions (lactate)
