This document discusses blood gas analysis and acid-base disorders. It provides details on parameters measured in blood gas analysis like PaO2, PaCO2, HCO3-, and how they are used to evaluate respiratory failure and classify acid-base imbalances. Respiratory failure is classified as type I or II based on PaO2 and PaCO2 levels. Various acid-base disorders like respiratory acidosis, respiratory alkalosis, metabolic acidosis, and metabolic alkalosis are defined based on changes in pH, PaCO2, and HCO3-. Mixed acid-base disorders involving combinations of respiratory and metabolic components are also described.
9. Other Parameters
SaO2: Saturation of arterial blood oxygen
Normal: 0.95-0.98
Significance: a parameter to evaluate
hypoxia, but not sensitive
ODC ( Dissociation curve of oxygenated
hemoglobin): “S” shape
11. PH 2,3DPG temperature CO2
ODC to right deviation
Oxygenated hemoglobin release oxygen
to tissue, prevent hypoxia of the tissue.
But absorbed oxygen of hemoglobin is
decreased from the alveoli.
Bohr effect: movement of ODC place is
induced by PH.
12. PA-aO2: Difference of alveoli-arterial blood
oxygenic partial pressure.
Normal: 15-20mmHg (<30mmHg in the old)
Significance: a sensitive parameter in gas
exchange
13. PvO2: Oxygenic partial pressure of mixed
venous blood.
Normal: 35-45mmHg
mean: 40mmHg
Significance: Pa-vO2 is to reflect the tissue
absorbing oxygen.
14. CaO2: The content of the oxygen of the
arterial blood.
Normal: 19-21mmol/L
Significance: a comprehensive parameter
to evaluate arterial oxygen.
15. Parameters in acid-basic disorder evaluation
PH: negative logarithm of Hydrogen
ion concentration.
Normal: 7.35-7.45
mean: 7.4
〔 HCO3- 〕
PH=Pka+log
0.03PaCO2
20
=
1
6.1+log
16. HCO3- (bicarbonate):
SB (standard bicarbonate)
AB (actual bicarbonate)
SB: the contents of HCO3- of serum of arterial
blood in 38℃ , PaCO2 40mmHg, SaO2 100%.
Normal: 22-27mmol/L
mean: 24mmol/L
AB: The contents of HCO3- in actual condition.
In normal person: AB=SB
17. AB and SB are parameters to reflect
metabolism, regulated by kidney.
Difference of AB-SB can reflect the
respiratory affection on serum HCO3- .
Respiratory acidosis: AB>SB
Respiratory alkalosis: AB<SB
Metabolic acidosis: AB = SB<Normal
Metabolic alkalosis: AB=SB>Normal
18. Buffer bases ( BB) :
is the total of buffer negative ion of
blood.
BB: HCO3-
hemoglobin
plasma proteins
HPO42- (phosphate)
Normal: 45-55mmol/L
mean: 50mmol/L
Significance: Metabolic acidosis: BB
Metabolic alkalosis: BB
19. Bases excess ( BE):
the acid or bases used to regulate blood
PH 7.4 . ( in 38℃ , PaCO2 40mmHg,
SaO2 100%)
Normal: 0±2.3 mmol/L
Significance:
add acid: BE(+), BB
add base: BE(-), BB
20. Total plasma CO2 (T-CO2) :
total content of the CO2 .
Normal: HCO3- >95%
21. Anion gap (AG):
the difference of undetermined anion
and undetermined cation in serum.
AG=Na+ - (Cl-+ HCO3- )
Normal: 8-16mmol/L
Significance:
AG acidosis: ketoacidosis, kidney failure
AG normal acidosis: Cl , diarrhea, fixed
acid decrease
to evaluate mix acid-basic disorder
22. Regulation of Acid-basic Balance
Chemical buffer
Dielectric changes of incells and excells
H+---K+, HCO3- ---Cl-
Physiology regulation of the lung and
kidney
23. Classification of Acid-basic Disorder
Complementary: PH is normal
Dis-complementary: PH is abnormal.
PH,PaCO2, HCO3- are three important
parameters in acid-basic disorder
evaluation.
24. Classification of Acid-basic Disorder
PH PaCO2 HCO3-
Resp. acidosis
Resp. alkalosis
Meta. acidosis
Meta. alkalosis
25. Classification of Acid-basic Disorder
Mixed acid-basic disorder
Complementary formula
example:
original disorder: chronic respiratory
acidosis
⊿ HCO3- =⊿ PaCO2 ×0.35±5.58
complementary limit: 45mmol/L
26. Classification of Acid-basic Disorder
Respiratory acidosis with metabolic acidosis
Respiratory acidosis with metabolic alkalosis
Respiratory alkalosis with metabolic acidosis
Respiratory alkalosis with metabolic
alkalosis