Hypoxia
The Department of Pathophysiology
Guo lirong
Definition of hypoxia (What is hypoxia?)
Parameters of Blood Oxygen
HypoxiaMain points to study
External respiration
BloodBlood CirculationCirculation
Tissue Tissue cellscells
OxygenOxygen SupplySupply
OxygenOxygenUtilizationUtilization
Hypoxia
Definition
Hypoxia is the commonest pathological process , which is defined as that cells can not obtain enough oxygen or can not fully utilize oxygen , thus leading to changes in their metabolism , function , or structure.
Hypoxia
1.Partial pressure of oxygen1.Partial pressure of oxygen (( POPO22
))2.Oxygen binding capacity2.Oxygen binding capacity (( COCO2 max2 max ))
3.Oxygen content3.Oxygen content (( COCO22 ))
4.Oxygen saturation4.Oxygen saturation ( ( SOSO22 ))
Parameters of Blood OxygenHypoxia
Partial pressure of oxygen ( PO
2 )
1.Definition : the tension produced by oxygen molecules physically dissolved in plasma.
2.Normal value : PaO2=13.3kPa(100mmHg)
PvO2=5.33kPa(40mmHg)
Hypoxia
Oxygen binding capacity ( CO2ma
x ) 1. Definition : It is the maximum amount of oxygen that can be combined to hemoglobin in 100 ml of blood.
2.Normal value : 20ml/dl
Hypoxia
Oxygen content ( CO2 )
1.Definition : It is the actual content of oxygen in 100ml blood.
2.Normal value : CaO2=19ml/dl CvO2=14ml/dl
Hypoxia
Arteriovenous oxygen content (Ca-vO2)
19ml/dl 14ml/dl
5ml/dl
O2O2 O2O2 O2O2 O2O2 O2O2A V
Definition: It is the difference of oxygen content between arterial blood and mixed venous blood.Normal value : 5ml/dl
Definition: It is the percentage of hemogl
obin present as oxyhemoglobin.
Oxygen saturation (SO2)
Normal value : SaO2=95%; SvO2=70%
CO2-dissolved O2
CO2max100%
=SO2
Hypoxia
P50
Definition: P50 is a parameter reflecting t
he affinity of Hb to oxygen; it is the O2 p
ressure required to sturate 50% of Hb.
Normal value : 26~28 mmHg
Dissociation curve of oxyhemoglobinDissociation curve of oxyhemoglobin
20
40
60
80
100
20 40 60 80 100
Hb
Sat
ura
tion
(%
Hb
Sat
ura
tion
(%
))
PaOPaO22 (mmHg) (mmHg)
pH↓pH↓2,3-DPG↑2,3-DPG↑CO2 ↑↑Temperature↑↑
Leftward-shifteLeftward-shifted curve:d curve:
Rightward-shifteRightward-shifted curved curve
Hypoxia