1. Rhonda Contant, BScH, RRT
Oxygen Therapy
Rhonda Contant, BScH, RRT

2. Let’s Start with the Basics!
How much O2 is in room air?
How much O2 comes out of a flowmeter?

3. Oxygen Therapy O2 delivery systems: design and performance
Three basic designs exist
Low-flow systems
Reservoir systems
High-flow systems
There are numerous oxygen modalities available to choose from when treating pts.
Design and performance = Proper device selection requires knowledge of the general performance characteristics as well as the individual capabilities.
O2 delivery devices are categorized by design – low flow, high flow and reservoir.

4. We need to answer 2 key questions…
How much O2 can the system deliver?
What is the FiO2 or FiO2 range of the device?
Does the FiO2 vary or remain fixed with changing pt demands?
Does everyone know what I mean when I say FiO2?? Fractional concentration of O2 = the concentration of O2 on inspiration
Different devices can deliver different O2 concentrations, so we need to know what FiO2 we need or what range before we make our choice.
Secondly, is it important to provide a fixed or variable FiO2?

5. Fixed or Variable FiO2?
Depends on how much of the pt’s inspired gas the device delivers
Fixed means the FiO2 stays the same
Variable mean the FiO2 fluctuates.

6. Fixed or Variable FiO2? Fixed FiO2
The device is designed to deliver ALL the pt’s inspired gas  FiO2 is constant or fixed
Fixed delivers ALL the pts inspired gas even under changing pt demands ie increased RR or Vt

7. Fixed or Variable FiO2? Variable FiO2
The device provides only SOME of the inspired gas
The pt must draw the rest from the surrounding environment (room air)
What happens if we mix O2 with room air?
Dilutes the delivered O2  lowers FiO2
The result = variable FiO2 from breath to breath depending on pt demands

8. Low Flow Systems: Uses low flows (< 8 Lpm)
They are variable systems therefore the pts demands will affect the FiO2
Keep in mind flow > 6Lpm are very drying (no humidity in O2, the humidity is removed when it is processed) and can lead to nasal dryness and bleeding.
Factors that affect (decrease) FiO2 = Examples: increased RR, large Vt and open mouth breating

9. Low Flow Systems: Nasal cannula Delivers an FIO2 of 0.24 to 0.40
Used with flow rates of ¼ to 8 L/min
FIO2 depends on how much room air the patient inhales in addition to the O2.
Device is usually well tolerated.
Humidifier should be used with flows > 4 Lpm
Books say 8 Lpm, but we don’t recommend >6 Lpm unless there are extenuating circumstances

10. Nasal Prongs / Cannula
Mosby items and derived items © 2009 by Mosby, Inc., an affiliate of Elsevier Inc.

11. How to Estimate the FiO2 for Nasal Cannula:
FiO2 = 21% + (4 x #Lpm)
Example: What is the approximate FiO2 when the flow meter is set at 2 Lpm?
FiO2 = 21% + ( 4 x Lpm)
FiO2 = 21% + ( 4x 2)
FiO2 = 29%

12. Reservoir Systems
Incorporate a mechanism to gather and store O2 between pt breaths
Pts draw from this reservoir when their inspiratory flows exceed the oxygen flow delivered by the device
Instead of diluting with room air, they dilute with O2  results in a higher FiO2
Incorporates this mechanism into a low flow system.
Normally with low flow systems the pt dilutes or draws in r/a to meet their needs.
With reservoir systems, they breath in from the reservoir to make up the difference…if they still require more, then they draw in r/a diluting the FiO2.

13. Reservoir Systems Reservoir cannula Designed to conserve oxygen
Nasal reservoir
Pendant reservoir
Can reduce oxygen use as much as 50% to 75%
Humidification usually not needed
Typically found in home care.
Aesthetically not too pleasing.
Need lower flows to achieve the same saturations b/c of less dilution with room air. B/c of low flows, don’t typically need humidification

14. Moustache Reservoir Cannula

15. Pendant Reservoir Cannula

16. Reservoir Systems Reservoir masks Most commonly used reservoir systems
Three types
Simple mask
Partial rebreathing mask
Nonrebreathing mask
All masks themselves are a type of reservoir to store O2 b/c they gather and store O2 b/w pt breaths.
Some systems incorporate another storing device ie. bag
Inc.

17. Simple Mask Simple mask at 5-10 lpm  35-50% FiO2
Requires a minimum flow of 5 Lpm in order to FLUSH out the CO2 from exhalation.
Provides a variable FiO2 b/c pt can still breath in though the ports if the volume in the mask does not meet their needs.
FiO2 will depend on INPUT FLOW, MASK VOLUME, PT BREATHING PATTERN AND AIR LEAK AROUND THE MASK
Mosby items and derived items © 2009 by Mosby, Inc., an affiliate of Elsevier Inc.

18. Partial and Non - Rebreathers
Left = Partial Rebreather
Right = non Rebreather.
Incorporates a 1 L reservoir bag attached to the O2 inlet that acts as a reservoir
Non rebreather uses one way valves to further increase the FiO2. Partial rebreather has no valves.
Partial rebreather – no valves, therefore on exhalation, some of the exhaled gas goes into the reservoir bag = approx the first third of the pts exhalation. This gas is coming from the pts anatomic deadspace (which has not undergone gas exchange), therefore is high in O2 and has essentially no CO2 and it mixes with gas coming from the flowmeter. The other 2/3 of exhalation get flushed out the ports on mask. (therefore rebreathing of CO2 is minimal)
On inspiration, the pt breaths in the O2 from the mask and then draws from the bag.
The result = moderate but variable FiO2 – 40 – 70% at flows of approx Lpm (enough to keep the bag inflated)
Non rebreather: - one one-way valve on mask and one on bag. Explain how they work. Inspiratory valve on bag, expiratory valve on mask
Again, requires flows high enough to prevent the bag from collapsing during inspiration
In theory can deliver 100%, but in reality can only deliver approx %
Why? B/c only one valve on mask portion to prevent suffocation in event that O2 becomes disconnected. This other port also allows for air dilution. As well may get leaks around the seal of the face.
Mosby items and derived items © 2009 by Mosby, Inc., an affiliate of Elsevier Inc.

19. High Flow Systems
Supply a given (or fixed) O2 concentration at a flow equaling or exceeding the patient’s peak inspiratory flow
Use air-entrainment or blending system to mix air and oxygen at very specific ratios to determine a specific oxygen concentration
Can ensure a fixed FIO2
These devices are designed to mix in specific ratios.
Example a 1:1 ratio of Air to O2 will produce an FiO2 of 0.60 (60%)
The higher the FiO2 the lower the total flow
The lower the FiO2 the greater the total flow
Why? B/c to get a lower FiO2 we have to mix more room air with it. Ex. 30% = 8 parts air and 1 part O2 = 9 total parts.
Therefore, lower FiO2 are gaurenteed to have flows high enough to meet or exceed the pts demands.
Higher FiO2 may not have flows great enough to meet the pts demands
What happens if the total flow is not enough to meet the pts demands? They will dilute with room air.

20. Air Entrainment or Venti Mask
You may hear this called a Venturi mask – this is incorrect! They do not apply the venturi principle.
Provide a fixed FiO2 at lower ranges ie 24-50% at set flows of 3Lpm (0.24 – 0.31) and 6 Lpm ( ) depending on setting.
If a patients saturations do not improve on this system, increasing the flow is not the solution. They are specially designed to work at the designated flow rates, therefore we need to change modalities.
Large volume nebulizers (Jet nebulizers) use this same principle but they provide humidity. Can’t exceed FiO2 of 0.50 (even though they say they go up to 100%)
Why not? Again, because the output or total flow is not enough to meet the pts demands, therefore they will dilute with room air and actually decease the actual FiO2.
Mosby items and derived items © 2009 by Mosby, Inc., an affiliate of Elsevier Inc.

21. High Flow Jet Nebs
Misty Ox is a brand name. It can deliver fixed FiO2 at 0.60 – 0.96 when the flowmeter is set at minimun 40Lpm
How is this possible? Crank it all the way open = approx. 45 Lpm will come out of the flowmeter.

22. Equipment for Aerosol Therapy
Airway appliances
Aerosol mask
Face tent
T-tube
Tracheostomy mask
All used with large-bore tubing
These devices are connected to the large volume nebulizer or High flow nebulizers.

23. Equipment for Bland Aerosol Therapy
Masks – traditional
Facetent – facial burns, claustrophobic pts can sometimes benefit from there, pts with nasal packing for epistaxis.
Trach mask – trachs

24. Equipment for Bland Aerosol Therapy
T-piece is used with ETT.

25. How do we know what to use?
Nasal Cannula
Uses:
Stable pts requiring low FiO2
Home care pts requiring long term O2
Advantages
Adults, peds and infants
Easy to apply
Disposable, inexpensive
Well tolerated
Can eat with them in place

26. How do we know what to use?
Nasal Cannula
Disadvantages
Easily dislodged
High flows uncomfortable
Can cause dryness and bleeding
Variable FiO2s

27. How do we know what to use?
Reservoir (NRBR)
Uses
Emergencies
Unstable pts (MI)
Acute hypoxemia
Smoke inhalation / CO poisoning
CHF

28. How do we know what to use?
Reservoir (NRBR)
Advantages
High FiO2
Adults and peds
Quick and easy to apply
Disposable and inexpensive
Disadvantages
Uncomfortable
Can’t eat with mask on
Risk of aspiration if pt vomits
Potential suffocation hazard

29. How do we know what to use?
Venti mask
Uses:
Unstable pts requiring precise low FiO2
Pts with variable RR and Tidal Volume
Advantages:
Easy to apply
Disposable and inexpensive
Stable, precise FiO2
Disadvantages:
Uncomfortable
Can’t eat with mask on
Noisy
Risk of aspiration if pt vomits

30. How do we know what to use?
Large Volume (Jet) Nebulizers
Uses:
Pts with artificial airways
Pts with supraglottic swelling
To help mobilize secretions
Advantages:
Provides humidification
Provides fixed FiO2
Disadvantages:
FiO2 varies with back pressure (ie condensation in tubing)
Increased risk for infection

31. FYIs O2 is a prescribed drug
For every connection there is a possibility for a leak
Vasoline and O2 don’t mix  use a water based lubricant to treat nasal and lip dryness
When in doubt, call RT, we are there to help!!

32. Questions?