Oxygen Delivery Devices Flashcards
What is the FiO2 of normal air?
0.21 (21%)
When doing ABGs how do you take into account oxygen devices?
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)
What type of oxygen administration systems are you more or less likely to know the FiO2?
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
4 types of low flow oxygen systems?
Nasal cannulae
Hudson masks
Trachestomy masks
Non-rebreather facemasks
Why are low flow systems more likely to produce a variable performance unpredictable FiO2?
They meet the patients inspiratory flow demands based on RR, inspiratory flow rate and length of expiratory pause
How do nasal cannulaes work?
provide oxygen reservoir in the nasopharynx which mixes with inspired air to increase FiO2
What is the fastest flow rate that a nasal cannulae can provide?
6L/min
What does the FiO2 usually increase to with the use of a nasal cannulae?
0.24-0.44 with max LPM
Advantages and disadvantages of using nasal cannulae?
Advantages are that it allows eating, drinking, talking
Disadvantages include nasal passage drying, nose bleeds, can easily become displaced
What is a Hudson mask? What is maximum flow rate? What is average FiO2? Disadvantages of a Hudson mask?
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
How does a non-rebreather mask work?
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
What is the average FiO2 provided by a non-rebreather mask? flow rate?
0.6-0.85
Flow rate is 10-15 LPM
How do you initially fill the reservoir bag on a non-rebreather mask?
Place your finger over the one way valve at the neck of the reservoir bag and watch it fill
How does a venturi mask work?
Venturi effect where the cross section narrows and therefore pressure decreases and speed increases fo the as particles
High airway flow
How do you find out the flow rate and FiO2 of a venturi mask? What FiO2s are available?
The colour of the aperture
0.24, 0.28, 0.35, 0.4, 0.6
How does a nebuliser mask work?
Converts liquids into aerosols for inhalation into the LRT by Venturi effect
How do you reduce the size of the droplets produced in a nebulizer?
Atomization of the droplets
Baffle in the jet stream which reduces the droplet size further
What is the optimal flow rate of a nebuliser?
4-6 LPM
What are the main 3 types of medication that are given via nebulizer?
Nebulized bronchdilators
Adrenaline
Dornase alpha
What is dornase alpha used for?
Hydrolyzes DNA in sputum of CF patients to redice viscosity and promote clearance
What type of oxygen administrative system is used for patients who cannot breathe for themselves? What does it consist of?
Bag valve mask/Ambu bag
O2 reservoir, self expanding bag, one way valves, universal adapter and clear flexible mask
What is the FiO2 and flow rate of a Ambu bag system (bag valve mask)?
FiO2 is 0.8
Flow rate is 12-15 LPM
What happens if you ventilate a patient too aggressively with a bag valve mask?
Distension of stomach, perforation
What is AIRVO?
Heated and humidified high flow nasal cannulae
What is the maximum flow rate of AIRVO?
60 LPM
Advantages of using heated and humidified high flow nasal cannulae?
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
What situations would AIRVO be used?
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
