Oxygen Champion

Question 1

What is SaO2?

Answer 1

Oxygen Saturation of arterial blood

Question 2

What is SpO2?

Answer 2

The oxygen saturation as detected by the pulse oximeter. (Pericutainious oxygen saturation)

Question 3

What is PaO2?

Answer 3

The partial pressure of oxygen dissolved in arterial blood plasma

Question 4

What is FiO2?

Answer 4

The fraction of inspired oxygen

Question 5

What is type 1 respiratory failure?

Answer 5

A failure to OXYGENATE causing a decrease in SpO2 and PaO2.
PaO2 < 50mmHg (NR: 80-100mmHg)
Normal CO2 between 35 and 45mmHg or possibly low CO2 cue to compensatory hyperventilation that occurs when SpO2 falls below 60mmHg.

Question 6

What is type 22 respiratory failure?

Answer 6

A failure to VENTELATE causing an increase in CO2 and a decrease in SpO2 and PaO2.
CO2 > 50mmHg (NR: 35-45mmHg)
pH <7.35 (NR: 7.35-7.45)
Decreased PaO2 as you are physically unable to move enough air into the alvioli to participate in gas exchange

Question 7

Any condition that results in an increase in carbon dioxide should increase the respiratory rate and the work of breathing. But respiratory muscles cannot sustain this and will have to rest. What is this called and what does it result in?

Answer 7

Decompensation
Results in: decreased ventilation, decrease PaO2, increased CO2 and decreased pH.
Type 2 respiratory failure

Question 8

What happens to the bohr effect curve in type 2 respiratory failure?

Answer 8

Moves to the right

Question 9

Is type 2 respiratory failure fixed with oxygen?

Answer 9

No- you must treat the cause

But if failure to ventilate is left untreated for too long it will result in failure to oxygenate too

Question 10

What can happen if you give someone in type 2 respiratory failure too much oxygen?

Answer 10

It can lead to hypercapnia as ventilation is depressed. This means they will become acidotic

Question 11

What percentage of COPD patients retain oxygen?

Answer 11

20%

Question 12

Give 3 conditions other than COPD that can lead to type 2 respiratory failure.

Answer 12

Spine curvature/chest deformities
Chronic muscle weakness
Obesity
(all struggle to expand chest wall)

Question 13

What makes people retain carbon dioxide when on oxygen?

Answer 13

Ventilation/perfusion mismatching
Haldane effect
Loss of hypoxic drive

Question 14

What is V/Q mismatching in type 2 respiratory failure?

Answer 14

Areas of poor ventilation have reactive vasoconstriction.
When excess oxygen is given, vasoconstriction reverses
=> perfusion becomes good but the ventilation is still poor (they are still not able to remove CO2 effectively because their work of breathing is impaired)
The CO2 diffusion gradient in the lungs is still bad.

Question 15

What is the haldane effect in type 2 respiratory failure?

Answer 15

Chronically hypoxic patients have low oxygen haemoglobin saturations
Therefore, carbon dioxide occupies the empty sites on haemoglobin.
Giving high flow oxygen will push carbon dioxide off haemoglobin into the blood => increased H+ ions. It is not blown off in the lungs.
The CO2 diffusion gradient in the lungs is still bad.

Question 16

What is the loss of hypoxic drive in type 2 respiratory failure?

Answer 16

Normal respiration is driven by carbon dioxide receptors.
Chronic hypercapnia => desensitisation of these receptors
Oxygen receptors then become important in regulating breathing. If you give too much oxygen, you may suppress breathing leading to increased carbon dioxide retention.

Question 17

Can chronically hypoxic patients without carbon dioxide retention still become acidotic if too much oxygen is given?

Answer 17

Yes because of the haldane effect

Question 18

What are the clinical signs of hypoxia?

Answer 18

Altered mental state, Cayanosis, dysponea, tachypnoea and arrythmias
Hyperventilation increases when PaO2 <5.3kPa
Loss of consciousness ~4.3kPa
Death ~2.7kPa

Question 19

What is the surviving sepsis guidelines for SaO2?

Answer 19

85-95%

Question 20

What is shunting?

Answer 20

Perfusion without ventilation

Question 21

What is dead space?

Answer 21

Ventilation without perfusion

Question 22

Give 4 types of hypoxia and their causes

Answer 22

Circulatory hypoximia = MI, toniquae
Anaemic hypoxia = iron deficiency, blood loss, low olate or vitamin B12
Toxic hpoxia = Alcohol, cyanide, CO
Hypoxaemia hypoxia = Low inspired oxygen (altitude), alveolar hypoventelation (opiate over dose, scoliosis, obesity, anaphylaxis), impaired diffusion (interstitial thickening/ vascular dysfunction), V/Q mismatch

Question 23

Target SaO2 saturations for those in type 2 respiratory failure?

Answer 23

88-92%

Question 24

Target SaO2 saturations for those in type 1 respiratory failure?

Answer 24

94-98%

Question 25

List 4 types of oxygen delivery?

Answer 25

Nasal canula.
Variable performance face mask
Venturi mask
Non rebreathing mask