Prescribing oxygen- Anaesthetics

Question 1

What are the goals of oxygen therapy?

How are these assessed?

Answer 1

• Relieve hypoxia + maintain tissue perfusion
• Allow sufficient oxygenation without excessive CO2 retention + maintaining hypoxic drive
• Reduce work of breathing [CPAP]
• Clearance of secretions + humidification of air- limiting adverse effects of hypothermia + water loss
• Measure SpO2 [pulse oximetry] and SaO2 [ABG] + clinical signs/NEWS

Question 2

Does oxygen need to be prescribed?

Answer 2

Yes

Question 3

O2 targets for:
Normal people
COPD

Answer 3

O2 targets for:
Normal people- 94-98%
COPD- 88-92%- look at baseline sats on admission too

Question 4

What are the modes of oxygen delivery?

Answer 4

• Nasal cannulae
• Hudson facemask
• Venturi facemask
• Non rebreather mask [acute]
• CPAP + BiPAP [ventilation]

Question 5

What are the features of nasal cannulae oxygen delivery?

FiO2
Flow rate
Uses

Answer 5

• Low FiO2- 24-30%
• Flow rate= 1-4 L/min

Uses:
Mild hypoxia
Non acute

Question 6

What are the features of Hudson facemask oxygen delivery?

FiO2
Flow rate

Answer 6

• FiO2= 30-40%

- Flow rate= 5-10 L/min

Question 7

What are the features of Venturi mask oxygen delivery?

FiO2
Flow rate
Uses

Answer 7

• Different colours with different flow rates
• FiO2- 24-60% [depending on colour]
• Uses- COPD

Question 8

What are the features of a non rebreather oxygen delivery?

FiO2
Flow rate
Uses

Answer 8

• ACUTE settings - [where sharp inhalation causes high peak inspiratory flow so high flow rate rate to match]
• Valve stops patient rebreathing expired air
• FiO2- 60-90%
  -Flow rate- 15 L/min
  -

Question 9

What are the two modes of non invasive ventilation?

What are their features?
When are they used?

Answer 9

Cpap
-
-
-
-

Bipap
-
-
-
-

Question 10

What are the two modes of non invasive [positive pressure] ventilation?

What are their features?
When are they used?

Answer 10

CPAP

• Continuous positive airways pressure
• High positive pressure all the time
• “Splint the airways/ lungs open”
• High pressure O2 + tight fitting mask

-Uses: Type 1 resp failure- focal- get O2 to hypoxic area + sleep apnea [obstructive]

BiPAP

• Bilevel positive airways pressure
• High positive pressure on inspiration, low positive pressure on expiration
• Uses: Type 2 Resp failure- COPD