Oxygen therapy: What FiO2 are they actually getting?

Esme12, ASN, BSN, RN · Sep 9, 2014

This may help....http://www.ccpnetwork.ca/GWG/resources/Oxygen_Devices.pdf

1. Nasal Cannula: The nasal cannula is the most common oxygen device used and the most convenient for the patient. A nasal cannula at 2lpm is usually a good place to start.
You may at times need to estimate the FiO2. How to estimate FiO2 on a nasal cannula? For every liter per minute, the FiO2 increases by 4% as per the chart below:
1 lpm = 24%
2 lpm = 28%
3 lpm = 32%
4 lpm = 36%
5 lpm = 40%
6 lpm = 44%
The liter flow on a nasal cannula should never exceed 6lpm, as studies show doing so is of no added benefit to the patient. Also note that the prongs of a nasal cannula should face down.
A bubbler can be added to humidify the nose to prevent nasal drying and bleeds. This is automatically set up at flows greater than 4lpm, or as ordered by physician.
3. Non-Rebreather Mask (NRB): This is a mask that ideally will bring in 100% Fio2 so long as the liter flow is 15 and there is a good seal between the mask and the patient's face. And all three one-way valves are on the mask to prevent air entrainment.
For legal purposes, however, one flap is always removed just in case the oxygen gets shut off. And therefore the highest FiO2 you can get from an NRB is 75%. The bag acts as a reservoir for oxygen, and therefore allows device to provide higher FiO2s to the patient.
4. Partial Rebreather Mask (PRB): This is basically an NRB with both one-way valves removed from the mask. The estimated FiO2 is 60-65%. Flow should be set at 6-15 lpm.
High Flow Oxygen Devices: These devices meet the inspiratory flow of the patient, and generate accurate FiO2s so long as there is a good seal between the mask and the patient's face. The flows are such that the patient will not be entraining room air that will lower the FiO2. Respiratory rate and tidal volume of the patient have no effect on FiO2 delivered.
Ideally, the larger the entrainment port on the device the lower the FiO2, and the smaller the entrainment port the higher the FiO2. A major disadvantage is a mask is required, and this may be a bit more uncomfortable than a nasal cannula.
1. Venturi Mask: This mask is ideal for patients who are in respiratory distress with high tidal volumes or high respiratory rate to guarantee a certain amount of oxygen.
If a nasal cannula does not provide adequate oxygenation, Venturi Masks set from 28% to 40% are ideal for COPD patients.
Modern Venturi masks come with one or more color coded caps, and whichever one you use the desired liter flow for that particular cap is written right on the cap.
The Venturi Masks used at MMC are set up as follows:
A. White cap:
35% FiO2 set lpm at 9
40% FiO2 set lpm at 12
50% FiO2 set lpm at 15
B. Green cap:
24% FiO2 set lpm at 3lpm
26% FiO2 set lpm at 3lpm
28% FiO2 set lpm at 6lpm
30% FiO2 set lpm at 6 lpm
The liter flow must be at least set at the recommended liter flow for any particular FiO2 that is dialed in. It's okay if it is set too high, yet if it's too low the patient may retain CO2 and the FiO2 may not be lower than what you dialed in.
2. Aerosol set-up: This device will deliver anywhere from 21 to 100% FiO2 depending on how it is set up. The desired flow to set the flow meter at is written write on the cap
Usually a humidity device is connected to the flowmeter, and wide bore tubing connects this to the patient's mask Wide bore tubing acts as a reservoir to obtain higher FiO2s.
These are ideal for patients with tracheotomies because it allows for inspired air to be oxygenated, humidified and even heated if necessary. They can be hooked up to a simple mask, tracheotomy mask, and even a t-piece.
The flow may exceed the required flow, although if it is less the patient may retain CO2, and the FiO2 be lower than desired. On inhalation a mist should be seen coming from mask or reservoir.
3. High flow nasal cannula: An Fio2 of 21% to 100% may be maintained because the flow meets the patient's spontaneous inspiratory demand. This is made possible due to thicker tubing and humidified oxygen.