Acid-Base Flashcards
How to calculate the required amount of base for metabolic acidosis.
Required amount of base (mmol) = ABE x BWkg x K
K: small animals = 0.3, large animals = 0.2
Sample used in acid-base/ blood-gas determination.
Heparinised full blood.
Formula for anion gap
(Na+K+UC) - (Cl+HCO3-+UA)
What are the unmeasured cations
Ca2+
Mg2+
Globulins
What are the unmeasured anions
Negatively charged proteins
Phosphate
Lactate
Anion gap reference range
8-16 mmol/L
pH definition
-log(H+)
pH of blood
7.35-7.45
pCO2 definition
Partial carbon dioxide pressure.
Respiratory parameter.
pCO2 value
40 mmHg
HCO3- definition
Standard bicarbonate concentration of plasma.
Its value depends on pCO2, so blood must be equilibrated to 37 degrees and 40 mmHg pCO2.
Metabolic parameter.
HCO3- reference range
21-24 mmol/L
ABE definition
Actual base excess.
The amount of acid or base needed to equilibrate blood to pH 7.4.
pCO2 is stabilised at 37 degrees to 40 mmHg.
Metabolic parameter.
ABE reference range
+/- 3.5 mmol/L
tCO2 definition
Total CO2 in plasma.
The amount of CO2 liberated by strong acid.
tCO2 reference range
23-30 mmol/L
SBE definition
Standard (in vivo) base excess.
metabolic parameter.
SBE reference range.
+/- 3 mmol/L
Sample for blood gas analysis.
Arterial sample of Ca-equilibrated Li-heparinised blood.
Astrup-technique (no air contamination) and measured within 15 minutes or placed on ice to minimise changes in blood partial gas pressure as a result of continued metabolism.
paO2 definition
Partial arterial pressure of oxygen.
Indicates the ability of the lungs to oxygenate blood.
paO2 reference range
88-118 mmHg
paCO2 definition
Partial arterial pressure of carbon dioxide.
Indicates the ability of the alveolar gas exchange to remove CO2.
It is directly proportional to the rate of CO2 production, and inversely proportional to alveolar ventilation.
paCO2 reference range.
35-45 mmHg
SatO2 definition
Oxygen saturation calculated from Hb and O2.
Oxygen-saturated Hb/ total Hb
SatO2 reference range
Venous: 75-80 %
Arterial: 90-100 %
FiO2 definition
Fraction of inspired oxygen.
It is the assumed % of the O2 concentration participating in the gas exchange in the alveoli.
FiO2 reference range
Room air: 20.9%
O2 enriched: 21-100%
> 50% means a risk of O2 toxicity
Hypoventilation
paCO2 > 45 mmHg
+/- hypoxaemia. Depends on the degree of hypercapnia and the FiO2
Hyperventilation
paCO2 < 35 mmHg
Hyperoxaemia usually present together with increased SatO2
