I had a trach once with FI02 at 40%... I just looked at my records - lindawordlady

Maybe this will help - Janie

This might help some:

Face mask or tracheostomy mask with entrainment device

Simple face mask or Tracheostomy mask with entrainment device used in conjunction with humidification system.

This is system is useful in accurately delivering low concentrations of oxygen (24-35%). It can provide total ventilatory requirement unaffected by the pattern of ventilation by the entrainment of room air into the delivery system which increases the total air flow to patient and to deliver a specific FiO2. Rebreathing of expired gas is not a problem because the mask is flushed by the high flow rates. Therefore this system reduces the risk of carbon dioxide retention.

NOTE: While a specific FiO2 is delivered to the patient, the inspired FiO2 rate (ie what the patient actually receives) varies as this is dependent on:

      flow rate

      mask size and fit

      the patient's ventilation rate

Entrainment Devices

      Entrainment devices entrain (draw in) room air into the delivery system. This mixes with the oxygen flow from the wall to give the desired oxygen percentage. 

      Total flow must exceed the patient's peak inspiratory demand.

      To ensure that the patient's ventilatory requirements are met, read the product information and set the entrainment device and wall flow according to the manufacturer's recommendations (see the diagram opposite).

      Oxygen should be humidified and warmed (set at 33 degrees Celsius) as dry compressed gas is drying and may damage the tracheal mucosa.

      Not effective for FiO2 greater than 0.50 (if >50% required consider a non - rebreather mask) 

http://www.rch.org.au/rchcpg/index.cfm?doc_id=13531