Hypoxia

Июль 24, 2022

Содержание

2. Parameters Classification, etiology and mechanism of hypoxia Alterations of metabolism and function in the body Pathophysiological
3. parameters PO2 CO2max CO2 SO2 P50
4. PO2 partial pressure of oxygen PO2 is the tension produced by the oxygen molecules physically dissolved
5. CO2max oxygen binding capacity of hemoglobin CO2max refers to the maximal amount of oxygen that could
6. CO2 oxygen content CO2 includes oxygen that is bound to hemoglobin and physically dissolved in the
7. SO2 oxygen saturation SO2 is the percentage of hemoglobin present as oxyhemoglobin . Normal value: SaO2:
8. The relation between oxygen partial pressure and oxygen saturation is shown as oxygen dissociation curve (ODC).
9. P50 means the oxygen partial pressure required to saturate 50% of the hemoglobin, which reflects the
10. Classification, etiology, mechanism of hypoxia Hypotonic hypoxia Hemic hypoxia Circulatory hypoxia Histogenous hypoxia
11. Hypotonic hypoxia hypoxic hypoxia Hypotonic hypoxia is characterized by the decrease of PaO2(less than 60mmHg).
12. Etiology and mechanism Decreased PO2 of inspired air high altitude External respiratory dysfunction hypoventilation impaired diffusion
13. Characteristics of blood oxygen PaO2↓, SaO2↓, CaO2 ↓, CO2max N, CaO2-CvO2 ↓/N Cyanosis refers to the
14. Hemic hypoxia isotonic hypoxia Hemic hypoxia refers to the altered affinity of Hb for oxygen or
15. Etiology and mechanism Anemia Carbon monoxide poisoning CO can react with Hb to form carboxyhemoglobin which
16. Methemoglobinemia The ferrous state (Fe2+) in Hb may be oxidized to the ferric state (Fe3+) under
17. when a lot of pickled vegetables containing nitrate are taken, the reabsorbed nitrite reacts with HbFe2+
18. High affinity of Hb for O2 Alkaline solution Depot blood
19. Characteristics of blood oxygen PaO2 N, SaO2N, CaO2 ↓/N, CO2max ↓/N, CaO2-CvO2 ↓ CaO2-CvO2 is below
20. Circulatory hypoxia hypokinetic hypoxia Circulatory hypoxia refers to inadequate blood flow leading to inadequate oxygenation of
21. Etiology and mechanism Tissue ischemia shock, left heart failure, thrombosis, arterial stenosis Tissue congestion shock, right
22. PaO2N, SaO2N, CaO2 N, CO2max N, CaO2-CvO2 ↑ Characteristics of blood oxygen Because the blood flows
23. Histogenous hypoxia Histogenous hypoxia refers to the tissue cells can not make use of the oxygen
24. Etiology and mechanism Inhibition of oxidative phosphorylation - tissue intoxicity cyanides, sulphuret, rotenone, ( cytochrome oxidase)
25. Characteristics of blood oxygen PaO2 N, SaO2N, CaO2 N, CO2max N, CaO2-CvO2 ↓ Oxygen content in
26. Alterations of metabolism and function Respiratory system Circulatory system Hematologic system Central nervous system Tissues and
27. Respiratory system Compensatory response Low PaO2 stimulates the chemoreceptor in carotid and aortic body, which reflexly
28. High altitude pulmonary edema Central respiratory failure respiratory inhibition, irregular respiratory rhythm and frequency, hypoventilation, e.g.
29. Circulatory system Compensatory response Increased cardiac output hyperventilation and pulmonary expansion stimulate lung stretch receptors, which
30. Redistribution of blood vasodilatation : heart and brain hypoxia metabolites, lactic acid, adenosine Ca2+ influx↓ vasoconstriction
31. Injury manifestation Pulmonary hypertension Decreased diastolic and systolic myocardial function Arrhythmia Vagus Nerve Decreased venous return
32. Hematologic system Compensatory response Increase in the amount of RBCs and Hb More EPO produced and
33. Plasma viscosity↑, blood flow resistance ↑, afterload of heart ↑ When PO2 is low markedly, 2,3-DPG
34. Central nervous system Acute hypoxia: headache, agitation, poor faculty of memory, inability to make judgment, depress
35. Tissues and cells Compensatory response Enhanced cell capacity for use of oxygen number and membrane surface
36. Injury manifestation Cell membrane injury Na+ influx cell swelling K+ efflux synthetic disorder Ca2+ influx phospholipase
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Слайд 2

Parameters
Classification, etiology and mechanism of hypoxia
Alterations of metabolism and function in

the body
Pathophysiological basis of prevention and treatment

Слайд 3

parameters
PO2
CO2max
CO2
SO2
P50

Слайд 4

PO2 partial pressure of oxygen
PO2 is the tension produced by the

oxygen molecules physically dissolved in plasma.

Normal PaO2: 100mmHg
PvO2: 40mmHg

Determined by PiO2 and pulmonary function

Слайд 5

CO2max oxygen binding capacity of hemoglobin
CO2max refers to the maximal amount

of oxygen that could be bound by the hemoglobin, which reflects the ability of hemoglobin carrying oxygen.

Normal value: 20ml/dl

Determined by quantity and quality of Hb

Слайд 6

CO2 oxygen content
CO2 includes oxygen that is bound to hemoglobin and

physically dissolved in the blood (0.3ml/dl).

Normal value: CaO2:19ml/dl
CvO2:14ml/dl

The arteriovenous oxygen content difference (CaO2-CvO2) reflects the oxygen volume of tissue uptake.

Determined by PO2 and CO2max

Слайд 7

SO2 oxygen saturation
SO2 is the percentage of hemoglobin present as oxyhemoglobin

Normal value: SaO2: 95%
SvO2: 75%

Слайд 8

The relation between oxygen partial pressure and oxygen saturation is shown

as oxygen dissociation curve (ODC).

An increase in 2,3-diphosphoglyceric acid (2,3-DPG), H+, PCO2 and temperature will shift the curve to the right, in turn to the left.

Слайд 9

P50 means the oxygen partial pressure required to saturate 50% of

the hemoglobin, which reflects the affinity of hemoglobin for oxygen.

Normal value P50:26-27mmHg

P50

Слайд 10

Classification, etiology, mechanism of hypoxia
Hypotonic hypoxia
Hemic hypoxia
Circulatory hypoxia
Histogenous hypoxia

Слайд 11

Hypotonic hypoxia
hypoxic hypoxia
Hypotonic hypoxia is characterized by the decrease

of PaO2(less than 60mmHg).

Слайд 12

Etiology and mechanism
Decreased PO2 of inspired air
high altitude
External respiratory dysfunction

hypoventilation
impaired diffusion
partial ventilation-perfusion imbalcance
Venous-to-arterial shunt
congenital heart disease, Tetralogy of Fallot

Слайд 13

Characteristics of blood oxygen
PaO2↓, SaO2↓, CaO2 ↓, CO2max N, CaO2-CvO2 ↓/N
Cyanosis

refers to the bluish color of skin, nails, lips and mucous membranes when the deoxyhemoglobin concentration of the blood in the capillaries is more than 5g/dl.

Слайд 14

Hemic hypoxia
isotonic hypoxia
Hemic hypoxia refers to the altered affinity of

Hb for oxygen or decrease in amount of Hb in the blood.

Слайд 15

Etiology and mechanism
Anemia
Carbon monoxide poisoning
CO can react with

Hb to form carboxyhemoglobin which can not take up oxygen. So there is a deficiency of Hb that can carry oxygen.
CO can inhibit glycolysis in RBC, which reduces the production of 2,3-DPG and shifts the ODC to the left, decreasing the amount of oxygen released.

Слайд 16

Methemoglobinemia
The ferrous state (Fe2+) in Hb may be oxidized

to the ferric state (Fe3+) under the action of oxidizers, e.g. nitrite and nitrobenzene, to form methemoglobin (HbFe3+OH), which loses the ability to carry oxygen.
Methemoglobin can also make the ODC of normal HbO2 shift to the left.

Слайд 17

when a lot of pickled vegetables containing nitrate are taken, the

reabsorbed nitrite reacts with HbFe2+ to form HbFe3+. The skin appears to coffee color. This phenomenon is called enterogenous cyanosis.

Enterogenous cyanosis

Слайд 18

High affinity of Hb for O2
Alkaline solution
Depot blood

Слайд 19

Characteristics of blood oxygen
PaO2 N, SaO2N, CaO2 ↓/N, CO2max ↓/N, CaO2-CvO2

↓

CaO2-CvO2 is below normal because PO2 in the capillary is declined rapidly due to reduced CaO2.

Severe anemia : pallor
CO poisoning : cherry red
Methemoglobinemia: coffee color

Слайд 20

Circulatory hypoxia
hypokinetic hypoxia
Circulatory hypoxia refers to inadequate blood flow leading

to inadequate oxygenation of the tissues, which is also called hypokinetic hypoxia.

Слайд 21

Etiology and mechanism
Tissue ischemia
shock, left heart failure, thrombosis, arterial stenosis

Tissue congestion
shock, right heart failure

Слайд 22

PaO2N, SaO2N, CaO2 N, CO2max N, CaO2-CvO2 ↑
Characteristics of blood oxygen
Because

the blood flows slowly in the capillary due to ischemia or congestion, the tissues will take more oxygen from unit volume blood.

Patient with circulatory hypoxia may appear cyanosis.

Слайд 23

Histogenous hypoxia
Histogenous hypoxia refers to the tissue cells can not make

use of the oxygen supplied to them, though the amount of oxygen delivered to them is adequate.

Слайд 24

Etiology and mechanism
Inhibition of oxidative phosphorylation
- tissue intoxicity

cyanides, sulphuret, rotenone,
( cytochrome oxidase)
Mitochondria injury
bacteriotoxin, radiation, free radical
Absence of Vitamin
Vit B1, Vit B2, Vit PP co-enzyme

Слайд 25

Characteristics of blood oxygen
PaO2 N, SaO2N, CaO2 N, CO2max N, CaO2-CvO2

↓

Oxygen content in vein increased because cells utilize less oxygen. The color of skin and mucous membrane are pink red flush.

Слайд 26

Alterations of metabolism and function
Respiratory system
Circulatory system
Hematologic system
Central nervous system
Tissues

and cells

Слайд 27

Respiratory system
Compensatory response
Low PaO2 stimulates the chemoreceptor in carotid and aortic

body, which reflexly causes ventilation to increase.

Слайд 28

High altitude pulmonary edema
Central respiratory failure
respiratory inhibition, irregular respiratory rhythm

and frequency, hypoventilation, e.g. periodic breathing, Cheyne-Stoke respiration, Biot’s breathing

Injury manifestation

Слайд 29

Circulatory system
Compensatory response
Increased cardiac output
hyperventilation and pulmonary expansion stimulate

lung stretch receptors, which reflexly excite sympathetic nerve.
Pulmonary vasoconstriction
Ca2+ influx↑, the action of vasoconstrictive substances and SN

Слайд 30

Redistribution of blood
vasodilatation : heart and brain
hypoxia metabolites,

lactic acid,
adenosine
Ca2+ influx↓
vasoconstriction : skin, kidney,
gastrointestinal tract
Capillary hyperplasia
HIF→VEGF

Слайд 31

Injury manifestation
Pulmonary hypertension
Decreased diastolic and systolic myocardial function
Arrhythmia Vagus Nerve
Decreased venous

return to heart
severe hypoxia

Слайд 32

Hematologic system
Compensatory response
Increase in the amount of RBCs and Hb
More

EPO produced and released by kidney
Improved RBC oxygen release capability
More 2,3-DPG produced from glycolysis process

Слайд 33

Plasma viscosity↑, blood flow resistance ↑, afterload of heart ↑
When PO2

is low markedly, 2,3-DPG will cause CaO2 to decrease.

Injury manifestation

Слайд 34

Central nervous system
Acute hypoxia: headache, agitation, poor faculty of memory, inability

to make judgment, depress or loss of coordination
Chronic hypoxia: impaired concentration, fatigue, drowsiness
cerebral edema and neuron injury

Слайд 35

Tissues and cells
Compensatory response
Enhanced cell capacity for use of oxygen
number

and membrane surface of mitochondria↑
activity of succinic dehydrogenase and cyt-oxidase ↑
Enhanced anaerobic glycolysis
ATP↓ and ATP/ADP ↓→phosphofructokinase ↑
Enhanced myoglobin
Low metabolic state

Слайд 36

Injury manifestation
Cell membrane injury
Na+ influx cell swelling
K+ efflux

synthetic disorder
Ca2+ influx
phospholipase
Ca2+-dependent protein kinase
Mitochondria injury severe hypoxia
Lysosome injury

Hypoxia

Содержание

ParametersClassification, etiology and mechanism of hypoxiaAlterations of metabolism and function in

parametersPO2CO2maxCO2SO2P50

PO2 partial pressure of oxygenPO2 is the tension produced by the

CO2max oxygen binding capacity of hemoglobinCO2max refers to the maximal amount

CO2 oxygen contentCO2 includes oxygen that is bound to hemoglobin and

SO2 oxygen saturationSO2 is the percentage of hemoglobin present as oxyhemoglobin

The relation between oxygen partial pressure and oxygen saturation is shown

P50 means the oxygen partial pressure required to saturate 50% of

Classification, etiology, mechanism of hypoxiaHypotonic hypoxiaHemic hypoxiaCirculatory hypoxiaHistogenous hypoxia

Hypotonic hypoxia hypoxic hypoxia Hypotonic hypoxia is characterized by the decrease

Etiology and mechanismDecreased PO2 of inspired air high altitudeExternal respiratory dysfunction

Characteristics of blood oxygenPaO2↓, SaO2↓, CaO2 ↓, CO2max N, CaO2-CvO2 ↓/NCyanosis

Hemic hypoxia isotonic hypoxiaHemic hypoxia refers to the altered affinity of

Etiology and mechanism AnemiaCarbon monoxide poisoning CO can react with

Methemoglobinemia The ferrous state (Fe2+) in Hb may be oxidized

when a lot of pickled vegetables containing nitrate are taken, the

High affinity of Hb for O2Alkaline solutionDepot blood

Characteristics of blood oxygenPaO2 N, SaO2N, CaO2 ↓/N, CO2max ↓/N, CaO2-CvO2

Circulatory hypoxia hypokinetic hypoxiaCirculatory hypoxia refers to inadequate blood flow leading

Etiology and mechanismTissue ischemia shock, left heart failure, thrombosis, arterial stenosis

PaO2N, SaO2N, CaO2 N, CO2max N, CaO2-CvO2 ↑Characteristics of blood oxygenBecause

Histogenous hypoxiaHistogenous hypoxia refers to the tissue cells can not make

Etiology and mechanism Inhibition of oxidative phosphorylation - tissue intoxicity

Characteristics of blood oxygenPaO2 N, SaO2N, CaO2 N, CO2max N, CaO2-CvO2

Alterations of metabolism and functionRespiratory systemCirculatory systemHematologic systemCentral nervous system Tissues

Respiratory systemCompensatory responseLow PaO2 stimulates the chemoreceptor in carotid and aortic

High altitude pulmonary edemaCentral respiratory failure respiratory inhibition, irregular respiratory rhythm

Circulatory systemCompensatory responseIncreased cardiac output hyperventilation and pulmonary expansion stimulate

Redistribution of blood vasodilatation : heart and brain hypoxia metabolites,

Injury manifestationPulmonary hypertensionDecreased diastolic and systolic myocardial functionArrhythmia Vagus NerveDecreased venous

Hematologic systemCompensatory responseIncrease in the amount of RBCs and Hb More

Plasma viscosity↑, blood flow resistance ↑, afterload of heart ↑When PO2

Central nervous systemAcute hypoxia: headache, agitation, poor faculty of memory, inability

Tissues and cellsCompensatory responseEnhanced cell capacity for use of oxygen number

Injury manifestation Cell membrane injury Na+ influx cell swelling K+ efflux

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