Respiratiry Failure

Question 1

What are the 4 stages of the oxygen cascade

Answer 1

Inspired gas - PiO2
Alveolar gas - PAO2
Arterial blood - PaO2
Cell - PO2

Question 2

What kind of gas exchange occurs in the lungs

Answer 2

Passive diffusion

Question 3

What factors effect alveolar PO2

Answer 3

Alveolar ventilation
Oxygen consumption
CO2 production

Question 4

What determines the alveolar to arterial PO2 difference

Answer 4

Shunting

Question 5

How is normal PaO2 calculated

Answer 5

13.6 - (0.044 x age in yrs) kPa

Question 6

Shunting

Answer 6

Areas of the lung that are perfused but not ventilated

Question 7

Factors increasing oxygen transport in blood

Answer 7

Low pH
Incr temp
More 2,3-DPG
incr CO2

Question 8

What is the difference between type 1 and type 2 respiratory failure

Answer 8

Type 1 just hypoxaemia
Type 2 hypoxaemia and hypercapnic

Question 9

What O2 and CO2 arterial partial pressures show type 1 respiratory failure

Answer 9

O2 - <8.0kPa
CO2 - normal

Question 10

What o2 and CO2 arterial partial pressures show type 2 respiratory failure

Answer 10

O2 - <8kPa
CO2 - >6kPa

Question 11

What type of respiratory failure is caused by lung failure

Answer 11

Type 1

Question 12

What type of respiratory failure is caused by pump failure

Answer 12

Type 2

Question 13

5 pathophysiological mechanisms of hypoxaemia

Answer 13

Ventilation perfusion mismatch
Anatomical R-L shunt
Impaired diffusion
Alveolar hypoventilation
Low partial pressure of inspired o2

Question 14

Reasons for hypoventilation

Answer 14

Increased resistance due to airway obstruction
Reduced compliance of lung tissue or chest wall
Reduced strength of resp muscles
Drugs reducing overall ventilation

Question 15

Signs of respiratory failure

Answer 15

Tachypnoea
Use of accessory muscles
Nasal flaring
Intercostal recession
Suprasternal recessiom
Tachycardia
Hypertension
Sweating
End organ hypoxia
Cyanosis
Asterixis
Bounding pulse

Question 16

What causes asterixis and bounding pulse

Answer 16

CO2 retention

Question 17

How does respiratory failure affect sympathetic tone

Answer 17

Increase

Question 18

First line respiratory failure investigations

Answer 18

Physical exam
Pulse oximetry
ARterial blood gas
Chest x ray

Question 19

Can pulse oximetry be used to assess ventilation

Answer 19

No

Question 20

Sourced of error in pulse oximetry

Answer 20

Poor peripheral perfusion
Dark pigmented skin
False nails/nail varnish
Lipaemia/hyperlipidaemia/protocol infusion
Bright ambient light
Poorly adherent probe
Excessive motion

Question 21

Do oximeters over or under read on patients with dark pigmented skin

Answer 21

Over read

Question 22

What is normal blood pH

Answer 22

7.35-7.45

Question 23

What is acidotic blood pH

Answer 23

<7.35

Question 24

What is alkalosis blood pH

Answer 24

> 7.45

Question 25

What 2 mechanisms drive blood pH

Answer 25

Respiratory Metabolic

Question 26

How can metabolic acidosis and respiratory acidosis be told apart

Answer 26

Metabolic - low HCO3 Respiratory - high CO2

Question 27

How can respiratory and metabolic alkalosis be told apart

Answer 27

Metabolic - high HCO3 Respiratory - low CO2

Question 28

Is HCO3 normal in respiratory or metabolic acidosis/alkalosis

Answer 28

Respiratory

Question 29

Is PaCO2 normal in respiratory or metabolic alkalosis

Answer 29

Metabolic

Question 30

Compensation

Answer 30

Body tries to adjust other buffers to keep pH normal

Question 31

What is normally the SpO2 target for patients receiving supplemental O2

Answer 31

94-98%

Question 32

What is the first line treatment for respiratory failure

Answer 32

Oxygen

Question 33

4 oxygen delivery systems

Answer 33

Nasal cannula Simple face mask Non rebreather mask Venturi mask

Question 34

Which masks could be used for a patient with normal vital signs

Answer 34

Nasal cannula, simple face mask

Question 35

Which mask could be used when a high O2 concentration is needed

Answer 35

Non rebreather mask

Question 36

Which face mask could be used for controlled treatment in long term respiratory failure

Answer 36

Venturi mask

Question 37

What are the different colours of Venturi masks from low to high flow rate + oxygen delivery

Answer 37

Blue White Yellow Red Green

Question 38

What needs to be monitored during oxygen therapy

Answer 38

Vital signs Arterial blood gas

Question 39

How is hypercapnia treated

Answer 39

Ventilation

Question 40

What sO2 should be aimed for in CO2 retainers

Answer 40

90-92% May need 85+