Oxygen Therapy

Question 1

What are the goals of oxygen therapy?

Answer 1

• Patient comfort
• Increase oxygen saturations to target
• Level of oxygen required (low level or high flow)
• Level of humidification

Question 2

How does oxygen therapy work?

Answer 2

• 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

Question 3

What are the different types of oxygen devices?

Answer 3

• Nasal cannula (low flow)
• Simple face mask (high flow)
• Non re-breathe mask
• Venturi mask (high flow)
• Non invasive ventilation (CPAP/BiPAP)

Question 4

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?

Answer 4

24%
Every litre beyond that increases the FiO2 by about 4 percent.

Question 5

When you use a flow rate of 2 litres per minute, what does your FiO2 increase to?

Answer 5

28%

Question 6

When you use a flow rate of 3 litres per minute, what does your FiO2 increase to?

Answer 6

32%

Question 7

When you use a flow rate of 4 litres per minute, what does your FiO2 increase to?

Answer 7

36%

Question 8

When you use a flow rate of 5 litres per minute, what does your FiO2 increase to?

Answer 8

40%

Question 9

When you use a flow rate of 6 litres per minute, what does your FiO2 increase to?

Answer 9

44%

Question 10

When you use a flow rate of 7 litres per minute, what does your FiO2 increase to?

Answer 10

48%

Question 11

When you use a flow rate of 8 litres per minute, what does your FiO2 increase to?

Answer 11

52%

Question 12

When you use a flow rate of 9 litres per minute, what does your FiO2 increase to?

Answer 12

56%

Question 13

When you use a flow rate of 10 litres per minute, what does your FiO2 increase to?

Answer 13

60%

Question 14

What is nasal cannulae?

Answer 14

• 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)

Question 15

What is the maximum flow rate of nasal cannula?

Answer 15

• 4-6 l/min
• But flow rate tends to be 1-4L/min (4L will dry the nose, 2L is more comfortable)

Question 16

What are the problems with nasal cannulae?

Answer 16

• Can lead to pressure sores around nose, cheeks and ears
• Drying
• Epistaxis
• Mouth breathing

Question 17

What is a Venturi mask?

Answer 17

• 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

Question 18

What is the oxygen percentage and flow rate of a blue Venturi mask?

Answer 18

• 24% O2
• 2-4 L/min

Question 19

What is the oxygen percentage and flow rate of a white Venturi mask?

Answer 19

• 28% O2
• 4-6 L/min

Question 20

What is the oxygen percentage and flow rate of a orange Venturi mask?

Answer 20

• 31% O2
• 6-8 L/min

Question 21

What is the oxygen percentage and flow rate of a yellow Venturi mask?

Answer 21

• 35% O2
• 8-10 L/min

Question 22

What is the oxygen percentage and flow rate of a red Venturi mask?

Answer 22

• 40% O2
• 10-12 L/min

Question 23

What is the oxygen percentage and flow rate of a green Venturi mask?

Answer 23

• 60% O2
• 12-15 L/min

Question 24

What is a non-rebreathe mask?

Answer 24

• 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

Question 25

What is the flow rate and oxygen percentage of a non-rebreathe mask?

Answer 25

• 10-15 L/min minimum
• Delivers 85-90% oxygen

Question 26

What is a simple face mask?

Answer 26

• 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

Question 27

What flow rate does a simple face mask deliver?

Answer 27

• No less than 5 L/min
• 40-60% oxygen

Question 28

What are the types of non-invasive ventilation?

Answer 28

• CPAP (continuous positive airways pressure)
• BiPAP (bilevel positive airways pressure)

Question 29

What is non-invasive ventilation?

Answer 29

• 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.

Question 30

What is CPAP?

Answer 30

• 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

Question 31

What is BiPAP?

Answer 31

• 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)