Oxygen: delivery devices
Oxygen delivery devices for medical student finals and OSCES
- Oxygen is delivered from taps above ward beds at 100% concentration
- It is then put through different devices at different rates to adjust the oxygen concentration that the patient inspires
- The percentage of oxygen inspired depends on the flow rate and the delivery device
- The flow rate can be set on the wall tap: it varies from 0 – 15L per minute
- Delivery devices work with different flow rates. They include…
- Deliver 24-30% oxygen
- Flow rate 1-4L/min (4L 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)
Hudson mask (rarely used)
- Delivers 30-40% oxygen
- Flow rate 5-10L/min
- Delivers 24-60% oxygen
- Different colours deliver different rates
- Flow rate: Varies with colour. The correct flow rate to use with each colour it is shown on mask, along with the percentage of oxygen delivered.
- 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.
- 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.
Non-invasive ventilation (CPAP/BiPAP): click here for how to start patients on NIV
- CPAP (continuous positive airways pressure)
- BiPAP (bilevel positive airways pressure)
- High positive pressure on inspiration and lower positive pressure on expiration
- Used in exacerbations of COPD and ARDS
- 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
Perfect revision for medical student finals, OSCES and PACES