Oxygen Delivery Devices - Flow Rates And FiO2

Nasal cannulae

• Deliver 24-30% oxygen
• Flow rate 1-5L/min (5L will dry the nose, 2L is more comfortable)
• Used in non-acute situations or if only mildly hypoxic (e.g. saturations stable at 92% in a patient without lung disease)

Face mask

• Delivers 30-40% oxygen
• Flow rate 10-12L/min

Non-rebreather mask

• Delivers 85-90% oxygen
• 15L flow rate
• Bag on mask with valves stopping almost all rebreathing of expired air

Used for acutely unwell patients

• Note that saturations should be maintained at 94-98%, not 100%.
• Do not keep patients on 15L for longer than necessary as over-oxygenating for prolonged periods can be harmful.

Venturi mask

• Delivers 24-60% oxygen
• Different colors deliver different rates
• Flow rate: Varies with color. 
• The correct flow rate to use with each color it is shown on mask, along with the percentage of oxygen delivered.

Types:

• BLUE = 2-4L/min = 24% O2
• WHITE = 4-6L/min = 28% O2
• YELLOW = 8-10L/min = 35% O2
• RED = 10-12L/min = 40% O2
• GREEN = 12-15L/min = 60% O2

Venturi masks are often used in COPD, where it is important not to over-oxygenate the patient.

Non-invasive ventilation (CPAP/BiPAP): 

• CPAP (continuous positive airways pressure)
• High pressure air/oxygen with a tight-fitting mask
• Positive pressure all the time to help keep airways open (split them)
• Used in acute pulmonary edema and sleep apnea
• BiPAP (bilevel positive airways pressure)
• High positive pressure on inspiration and lower positive pressure on expiration
• Used in exacerbations of COPD and ARDS

Invasive ventilation

• Fully controlled oxygen delivery up to 100%
• A ventilation bag or machine is attached to an artificial airway to ventilate lungs.
• Used in intensive care and theatre

SUMMARY