Oxygen

Question 1

How does oxygen travel in the blood?

Answer 1

Dissolved in plasma
OR
Bound to haemoglobin

Question 2

What is haemoglobin called when 4 O2 are attached?

Answer 2

Oxyhemoglobin (oxygenated haemoglobin) it is bright red (e.g. arterial blood)

Question 3

What is SaO2?

Answer 3

Oxygen saturation of arterial blood

Question 4

What is SpO2?

Answer 4

Oxygen saturation as detected by the pulse oximeter

Question 5

What is haemoglobin called when its not bound to oxygen?

Answer 5

Deoxygenated haemoglobin, it has a dark red colour (venous blood is dark red)

Question 6

What is PaO2?

Answer 6

The amount of oxygen dissolved in arterial blood plasma (partial pressure)

(measurement given as a pressure value mmHg or kph)

Question 7

What is the relationship between SpO2 and PaO2?

Answer 7

The oxyhemoglobin dissociation curve

Question 8

Describe the link between PaO2 and Partial pressure?

Answer 8

The amount of O2 dissolved in the blood is proportional to the partial pressure of oxygen. The amount of oxygen bound to hemoglobin will increase as the partial pressure of oxygen increases.

Question 9

Describe the O2 dissociation curve?

Answer 9

Not linear relationship though. S shared curve

Question 10

What is the standard temp and pH of the human body?

Answer 10

Temp - 37

pH - 7.35 - 7.45

Question 11

What is FiO2?

Answer 11

Fraction of inspired oxygen - a fraction of the amount of oxygen a patient is inhaling produced by an oxygen device such as a nasal cannula or mask.

Question 12

What is hypoxia?

Answer 12

deficiency in the amount of o2 reaching the tissues

The term hypoxia is a condition where the tissues are not oxygenated adequately, usually due to an insufficient concentration of oxygen in the blood.

Question 13

What happens if you give a patient with COPD too much O2?

Answer 13

They will start to retain CO2.

only some patients retain CO2 1/3, the rest of patients wont 2/3 of people

Question 14

What are some other causes of CO2 retention?

Cause Hypoxia… then cause CO2 retention.

Answer 14

• COPD
• Scoliosis (curvatures of the spine)
• CF (chronically low levels of O2)
• Bilateral tosis - neuromuscular disorders
• Morbid obesity

Question 15

Type 1 resp failure?

Answer 15

Low levels of O2 but CO2 levels are normal or low

Question 16

Type 2 resp failure?

Answer 16

Low levels of O2 but CO2 levels are high

• can be acute or chronic

Question 17

What do people with Chronic Type 2 resp failure often become?

Answer 17

They become acidotic very quickly - they will have a elevated bicarb level but their pH will be normal

Question 18

What would be the difference in someone with acute resp type 2 failure?

Answer 18

Too much CO2 in the body, Bicarb would be normal as it takes a while to make.
But their pH would decrease

Question 19

Why do these patients retain CO2?

Answer 19

• V/Q (ventilation/perfusion) Mismatching
• Areas of poor ventilation have reactive vasoconstriction
• Glve excess oxygen and that reactive vasoconstrtiction reverses
• Perfusion becomes good, but ventilation is still poor

Question 20

What is hypercapnia?

Answer 20

high levels of CO2 in the blood

Question 21

How does giving too much oxygen result in hypercapnia?

Answer 21

1. Reducing the “drive to breathe”. People with chronic obstructive pulmonary disease (COPD) can sometimes have higher CO2 levels than people with healthy lungs and therefore become less sensitive to CO2. The person then relies more on low oxygen levels to stimulate their breathing. Giving too much oxygen removes this stimulus to breathe, and thus reduces the removal of CO2 from the lungs. (hypoxic drive)
2. Both oxygen and CO2 bind to the haemoglobin in the red blood cells. Giving too much oxygen can push the CO2 from the haemoglobin into the bloodstream/plasma, causing CO2 levels to rise in the blood.
3. By dramatically changing the relationship between air exchange within the lungs and bloodflow within the lungs, resulting in reduced removal of CO2.

Question 22

What is hypoxeamia?

Answer 22

Low O2 conc in the blood

Question 23

What makes patients retain CO2? V/Q mismatching… explain?

Answer 23

V/Q or ventilation/perfusion refers to the amount of air that reaches the alveoli divided by the amount of blood that flows through the capillaries in the lungs.

Question 24

Describe what ventilation and perfusion relate to?

Answer 24

V stands for ventilation, the air that is breathed in through the nose and mouth, down through the trachea, into the bronchi, and then down through smaller airways into the smallest airways known as the alveoli where the exchange of oxygen and carbon dioxide takes place.

Q stands for perfusion or blood flow. From the heart, deoxygenated (“blue blood”) passes through the pulmonary arteries (which are more like veins because they have blood in need of oxygen) through smaller and smaller vessels and into capillaries (the smallest blood vessels) where oxygen and nutrient exchange takes place.

Question 25

Describe what would cause a decreased V/Q ratio?

Answer 25

A decreased V/Q ratio occurs when either there is decreased ventilation in the lungs or increased perfusion (more blood flow through the lungs).

E.g chronic bronchitis, foreign object, asthma

Question 26

Describe what would cause an increased V/Q ratio?

Answer 26

An increased V/Q ratio occurs when there is either increased ventilation or decreased perfusion (blood flow to the lungs.)

E.g. PE, Emphysema

Question 27

What makes patients retain CO2? Haldane effect… explain?

Answer 27

Chronically hypoxaemic patient has low Hb saturation
CO2 occupies the empty binding sites on the Hb
Giving a high FiO2 pushes the CO2 off the Hb, into the system

Question 28

Describe the different types of hypoxia?

Answer 28

Circulatory hypoxia - depends on the cardiac output
Anaemic Hypoxia
Toxic Hypoxia - due to toxins, affecting sautration of O2, attaching to haem
Hypoxaemic Hypoxia - lungs dont work in some way or another