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Cell Injury > Tissue Hypoxia > Flashcards

Tissue Hypoxia Flashcards

1
Q

Define hypoxia.

A

Inadequate oxygenation of tissue

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2
Q

What does pulse oximetry measure?

A

SaO2

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3
Q

Contrast the SaO2 levels detected by a pulse oximeter and a co-oximeter.

A

Pulse oximeter- falsely elevated SaO2 if dyshemoglobins are present
Co-oximeter- accurately measures SaO2 if dyshemoglobins are present

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4
Q

What are the clinical findings of tissue hypoxia?

A

Cyanosis
Confusion
Cognitive impairment
Lethargy

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5
Q

Detail the normal diffusion of oxygen from the atmosphere to the RBC.

A

Oxygen diffuses down a gradient from the atmosphere, to the alveoli, to plasma, into RBC where it attaches to heme groups

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6
Q

Define oxygen content.

A

A measure of the total amount of O2 carried in blood.

O2 content= Hb*SaO2+PaO2

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7
Q

What state must iron be in to carry oxygen?

A

2+ (ferrous)

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8
Q

Define oxygen saturation.

A

The oxygen in the RBC attached to heme groups

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9
Q

If the partial pressure of arterial oxygen decreases, what must happen to the oxygen saturation?

A

Decreases

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10
Q

Define ischemia.

A

Decreased arterial blood flow

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11
Q

What is the most common cause of ischemia?

A

Thrombus

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12
Q

Define hypoxemia.

A

Decrease in partial pressure of oxygen

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13
Q

When a person has respiratory acidosis, what has to happen to the PaO2?

A

Goes down- hypoxemia

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14
Q

What is the sum of the partial pressures of O2, CO2, and N in the alveoli at sea level?

A

760 mmHg

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15
Q

In addition to respiratory acidosis, what are other causes of hypoxemia?

A 
Decreased inspired PO2
Ventilation defect
Perfusion defect
Diffusion defect
Cyanotic congenital heart disease
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16
Q

Define ventilation defect.

A

Lung is perfused but not ventilated

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17
Q

Define perfusion defect.

A

Lung is ventilated but not perfused

18
Q

Define diffusion defect.

A

Decreased diffusion of oxygen through the alveolar-capillary interface

19
Q

What causes intrapulmonary shunting?

A

Ventilation defects

20
Q

What causes increased dead space?

A

Perfusion defects

21
Q

What are the causes of tissue hypoxia?

A

Ischemia
Hypoxemia
Hb abnormalities

22
Q

Respiratory distress syndrome (hyaline membrane disease) is an example of what type of V/Q defect?

A

Ventilation defect- lack of surfactant causes atelectasis

23
Q

A patient has hypoxemia and is given 100% oxygen. After 20 minutes, the PaO2 is checked and has not increased. What type of V/Q defect is present?

A

Shunt

24
Q

What is the most common perfusion defect?

A

PE

25
Q

What is the leading cause of death due to poisoning?

A

Carbon monoxide poisoning

26
Q

How do you treat carbon monoxide poisoning?

A

100% O2

27
Q

Do you see cyanosis in a patient with CO poisoning?

A

No- cherry red pigment

28
Q

Patients who are victims of a house fire are at risk of poisoning from what 2 compounds?

A

CO

Cyanide

29
Q

What is methemoglobin?

A

Iron is Fe 3+ (ferric)

30
Q

What color is the blood from a person with methemoglobinemia?

A

Brown

31
Q

What molecule reduces ferrous iron to ferric iron in Hb?

A

NADPH-methemoglobin reductase

32
Q

What is the treatment for methemoglobinemia?

A

IV methylene blue

Vitamin C- reducing agent

33
Q

What drug classes can produce methemoglobinemia?

A

Sulfa drugs

Nitro drugs

34
Q

Regarding the OBC, is a R shift or L shift better?

A

Right shift- increased release of oxygen

35
Q

What produces a left shift in the OBC?

A 
Alkalosis
Decreased 2,3-BPG
Decreased temperature
Increased HbF
CO poisoning
MetHb
36
Q

What produces a right shift in the OBC?

A

Acidosis
Increased 2,3-BPG
Increased temperature
Altitude

37
Q

Why does 2,3-BPG cause a right shift in the OBC?

A

2,3-BPG stabilizes taut form of Hb, this decreases the affinity of Hb for oxygen causing oxygen to move from Hb into plasma and into tissue by diffusion

38
Q

Enzyme inhibition at any level of oxidative phosphorylation decreases ATP synthesis and shuts down the ETC. This is easily remembered as the 3 C’s, what are these?

A

Cytochrome oxidase
CO
Cyandie

39
Q

Define uncoupling of oxidative phosphorylation.

A

Protons from the intermembranous space move through the innermitochondiral membrane into the mitochondtrial matrix and bypass ATP synthase

40
Q

Salicylic acid is a metabolite of what drug?

A

Aspirin- acetylsalicylic acid

41
Q

With any cause of hypoxia there is cellular swelling, why?

A

Decreased oxygen results in decreased ATP synthesis, this limits the Na-K ATPase leading to influx of Na and cellular swelling

42
Q

Why does calcium lead to irreversible cellular damage?

A

Activates enzymes

Cell Injury (3 decks)

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