Oxygen Therapy Flashcards
What are the goals of oxygen therapy?
- Patient comfort
- Increase oxygen saturations to target
- Level of oxygen required (low level or high flow)
- Level of humidification
How does oxygen therapy work?
- 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
What are the different types of oxygen devices?
- Nasal cannula (low flow)
- Simple face mask (high flow)
- Non re-breathe mask
- Venturi mask (high flow)
- Non invasive ventilation (CPAP/BiPAP)
Room air is 21 percent oxygen, so you are breathing a FiO2 of 21 percent without supplemental oxygen.
When you use a flow rate of 1 litre per minute, what does your FiO2 increase to?
24%
Every litre beyond that increases the FiO2 by about 4 percent.
When you use a flow rate of 2 litres per minute, what does your FiO2 increase to?
28%
When you use a flow rate of 3 litres per minute, what does your FiO2 increase to?
32%
When you use a flow rate of 4 litres per minute, what does your FiO2 increase to?
36%
When you use a flow rate of 5 litres per minute, what does your FiO2 increase to?
40%
When you use a flow rate of 6 litres per minute, what does your FiO2 increase to?
44%
When you use a flow rate of 7 litres per minute, what does your FiO2 increase to?
48%
When you use a flow rate of 8 litres per minute, what does your FiO2 increase to?
52%
When you use a flow rate of 9 litres per minute, what does your FiO2 increase to?
56%
When you use a flow rate of 10 litres per minute, what does your FiO2 increase to?
60%
What is nasal cannulae?
- Simple plastic tubing with prongs and over ear adjustment
- Used for supplementary oxygen therapy
- Used for long term oxygen therapy
- Used in non-acute situations or if only mildly hypoxic (e.g. saturations stable at 92% in a patient without lung disease)
What is the maximum flow rate of nasal cannula?
- 4-6 l/min
- But flow rate tends to be 1-4L/min (4L will dry the nose, 2L is more comfortable)
What are the problems with nasal cannulae?
- Can lead to pressure sores around nose, cheeks and ears
- Drying
- Epistaxis
- Mouth breathing
What is a Venturi mask?
- For those who require high flow constant oxygen
- O2 is directed through tubing to mixing port
- Final concentration depends on the correct amount of litres put through the device
- Good for those who are hypoxemic and cannot be controlled with low FiO2
- Delivers 24-60% oxygen
- Different colours deliver different rates
- Venturi masks are often used in COPD, where it is important not to over-oxygenate the patient
What is the oxygen percentage and flow rate of a blue Venturi mask?
- 24% O2
- 2-4 L/min
What is the oxygen percentage and flow rate of a white Venturi mask?
- 28% O2
- 4-6 L/min
What is the oxygen percentage and flow rate of a orange Venturi mask?
- 31% O2
- 6-8 L/min
What is the oxygen percentage and flow rate of a yellow Venturi mask?
- 35% O2
- 8-10 L/min
What is the oxygen percentage and flow rate of a red Venturi mask?
- 40% O2
- 10-12 L/min
What is the oxygen percentage and flow rate of a green Venturi mask?
- 60% O2
- 12-15 L/min
What is a non-rebreathe mask?
- Simple face mask with a reservoir bag (partially or fully inflated)
- Bag on mask with valves to prevent inhalation of exhaled gases
- Used for acutely unwell patients with severe hypoxia
What is the flow rate and oxygen percentage of a non-rebreathe mask?
- 10-15 L/min minimum
- Delivers 85-90% oxygen
What is a simple face mask?
- Simple or non-reservoir that covers nose and face
- Higher FiO2 (concentration of oxygen) can be delivered compared to nasal cannula
- Can be used as short term therapy
- Can be attached to a humidified circuit for longer term therapy
What flow rate does a simple face mask deliver?
- No less than 5 L/min
- 40-60% oxygen
What are the types of non-invasive ventilation?
- CPAP (continuous positive airways pressure)
- BiPAP (bilevel positive airways pressure)
What is non-invasive ventilation?
- Non-invasive ventilation (NIV) is the application of respiratory support via a sealed face-mask without the need for intubation
- Air, usually with added oxygen, is given through the mask under positive pressure; generally the amount of pressure is alternated depending on whether someone is breathing in or out.
What is 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 oedema and sleep apnoea
What is BiPAP?
- Bilevel positive airways pressure
- High positive pressure on inspiration and lower positive pressure on expiration
- Used in exacerbations of COPD and ARDS (Acute respiratory distress syndrome is a life-threatening lung injury that allows fluid to leak into the lungs)
