49 Hypoxia and Cyanosis

Question 1

Pasteur effect

Answer 1

Decreased O2 availability to cells results in an inhibition of oxidative phosphorylation and increased anaerobic glycolysis, a switch from aerobic to anaerobic metabolism,

Question 2

What happens to the cell in severe hypoxia?

Answer 2

when ATP production is inadequate to meet the
energy requirements of ionic and osmotic equilibrium, cell membrane depolarization leads to uncontrolled Ca2+ influx and activation of Ca2+-dependent phospholipases and proteases. These events, in turn, cause cell swelling, activation of apoptotic pathways, and, ultimately,
cell death.

Question 3

Which genes are upregulated in hypoxia?

Answer 3

glycolytic enzymes, such as phosphoglycerate kinase and phosphofructokinase, as well as the glucose transporters Glut-1 and Glut-2; and by growth factors, such as vascular endothelial growth factor (VEGF) and erythropoietin, which enhance erythrocyte production.

Question 4

symptoms of high altitude illness?

Answer 4

headache secondary to cerebral vasodilation, gastrointestinal symptoms, dizziness, insomnia, fatigue, or somnolence. HAPE and HACE.

Question 5

three mechanisms od respiratory hypoxia?

Answer 5

ventilation-perfusion mismatch; hypoventilation; intrapulmonary right-to-left shunting

Question 6

What is the height in which you can develop Hypoxia Secondary to High Altitude?

Answer 6

3000 m

Question 7

Causes of Hypoxia Secondary to Right-to-Left Extrapulmonary Shunting?

Answer 7

tetralogy of Fallot, transposition of the great arteries,

and Eisenmenger’s syndrome

Question 8

Explain Circulatory Hypoxia.

Answer 8

the Pao2 is usually normal, but venous and tissue Po2 values are reduced as a consequence of reduced tissue perfusion and greater tissue O2 extraction.

Question 9

Why is hypoxia due to an elevated metabolic rate different from that in other types of hypoxia?

Answer 9

skin is warm and flushed and cyanosis is usually

absent.

Question 10

Explain histotoxic hypoxia.

Answer 10

Cyanide and several other similarly acting poisons cause cellular hypoxia. The tissues are unable to use O2, and, as a consequence, the venous blood tends to have a high O2 tension.

Question 11

chronic mountain sickness

Answer 11

characterized by a blunted respiratory drive, reduced ventilation, erythrocytosis, cyanosis, weakness, right ventricular enlargement secondary to pulmonary hypertension, and even stupor

Question 12

central cyanosis can be detected reliably when the

Sao2 has fallen to which %?

Answer 12

85% and in dark-skinned persons, it may not be detected until it has declined to 75%.

Question 13

concentration of reduced hemoglobin in cyanosis?

Answer 13

reduced hemoglobin in capillary blood exceeds

40 g/L (4 g/dL)

Question 14

Causes of Central and Peripheral Cyanosis?

Answer 14

see in the chapter

Question 15

Digital clubbing occurs with methemoglobin or sulfhemoglobin?

Answer 15

Generally, digital clubbing does not occur with them.

Question 16

What is the most common cause of peripheral cyanosis?

Answer 16

most common cause of peripheral cyanosis is the normal vasoconstriction resulting from exposure to cold air or water.

Question 17

Causes of clubbing?

Answer 17

cyanotic congenital heart disease (see above), infective endocarditis, and a variety of pulmonary conditions (among them primary and metastatic lung cancer, bronchiectasis, asbestosis, sarcoidosis, lung abscess, cystic fibrosis, tuberculosis, and mesothelioma), as well
as with some gastrointestinal diseases (including inflammatory bowel disease and hepatic cirrhosis). In some instances, it is occupational, e.g., in jackhammer operators.

Question 18

Is clubbing reversible?

Answer 18

In certain circumstances, clubbing is reversible, such as following lung transplantation for cystic fibrosis.