Oxygen Delivery Devices

Question 1

What is the FiO2 of normal air?

Answer 1

0.21 (21%)

Question 2

When doing ABGs how do you take into account oxygen devices?

Answer 2

Make a note of the FiO2

If you can’t work out the fraction of oxygen then write how the oxygen is being administered (method and rate of admin)

Question 3

What type of oxygen administration systems are you more or less likely to know the FiO2?

Answer 3

Variable performance oxygen delivery devices you are less likely to get a stable FiO2
Fixed performance oxygen delivery devices you are more likely to get a known and stable FiO2

Question 4

4 types of low flow oxygen systems?

Answer 4

Nasal cannulae
Hudson masks
Trachestomy masks
Non-rebreather facemasks

Question 5

Why are low flow systems more likely to produce a variable performance unpredictable FiO2?

Answer 5

They meet the patients inspiratory flow demands based on RR, inspiratory flow rate and length of expiratory pause

Question 6

How do nasal cannulaes work?

Answer 6

provide oxygen reservoir in the nasopharynx which mixes with inspired air to increase FiO2

Question 7

What is the fastest flow rate that a nasal cannulae can provide?

Answer 7

6L/min

Question 8

What does the FiO2 usually increase to with the use of a nasal cannulae?

Answer 8

0.24-0.44 with max LPM

Question 9

Advantages and disadvantages of using nasal cannulae?

Answer 9

Advantages are that it allows eating, drinking, talking

Disadvantages include nasal passage drying, nose bleeds, can easily become displaced

Question 10

What is a Hudson mask? What is maximum flow rate? What is average FiO2? Disadvantages of a Hudson mask?

Answer 10

Clear plastic face mask over nose and mouth
Get to an FiO2 of around 0.36 -0.6
Maximum flow rate is 15 LPM
Disadvantages that you need patient compliance and it can become claustrophobic with inability to eat or drink

Question 11

How does a non-rebreather mask work?

Answer 11

It has an oxygen reservoir bag attached which has a unidirectional valve on inspiration
It has valves on the mask itself which are unidirectional for expiration

Question 12

What is the average FiO2 provided by a non-rebreather mask? flow rate?

Answer 12

0.6-0.85

Flow rate is 10-15 LPM

Question 13

How do you initially fill the reservoir bag on a non-rebreather mask?

Answer 13

Place your finger over the one way valve at the neck of the reservoir bag and watch it fill

Question 14

How does a venturi mask work?

Answer 14

Venturi effect where the cross section narrows and therefore pressure decreases and speed increases fo the as particles
High airway flow

Question 15

How do you find out the flow rate and FiO2 of a venturi mask? What FiO2s are available?

Answer 15

The colour of the aperture

0.24, 0.28, 0.35, 0.4, 0.6

Question 16

How does a nebuliser mask work?

Answer 16

Converts liquids into aerosols for inhalation into the LRT by Venturi effect

Question 17

How do you reduce the size of the droplets produced in a nebulizer?

Answer 17

Atomization of the droplets

Baffle in the jet stream which reduces the droplet size further

Question 18

What is the optimal flow rate of a nebuliser?

Answer 18

4-6 LPM

Question 19

What are the main 3 types of medication that are given via nebulizer?

Answer 19

Nebulized bronchdilators
Adrenaline
Dornase alpha

Question 20

What is dornase alpha used for?

Answer 20

Hydrolyzes DNA in sputum of CF patients to redice viscosity and promote clearance

Question 21

What type of oxygen administrative system is used for patients who cannot breathe for themselves? What does it consist of?

Answer 21

Bag valve mask/Ambu bag

O2 reservoir, self expanding bag, one way valves, universal adapter and clear flexible mask

Question 22

What is the FiO2 and flow rate of a Ambu bag system (bag valve mask)?

Answer 22

FiO2 is 0.8

Flow rate is 12-15 LPM

Question 23

What happens if you ventilate a patient too aggressively with a bag valve mask?

Answer 23

Distension of stomach, perforation

Question 24

What is AIRVO?

Answer 24

Heated and humidified high flow nasal cannulae

Question 25

What is the maximum flow rate of AIRVO?

Answer 25

60 LPM

Question 26

Advantages of using heated and humidified high flow nasal cannulae?

Answer 26

Anatomical dead space is reduced
mechanical stents to keep airway open
Reduced work of breathing
Improved muco-ciliary clearance - improved v/q
CPAP effect distending lungs to ensure they work - good for obese patients

Question 27

What situations would AIRVO be used?

Answer 27

acute hypoxic respiratory failure
Hypercapnic respiratory failure
Acute HF
Preventative therapy in post-extubation respiratory failure
Bronchoscopy
Pre-oxygenation in high risk patients prior to intubation