O2 therapy - Lecture Notes

Question 1

Oxygen therapy equipment is classified into two:

Answer 1

1) Low flow or variable performance
2) High flow or fixed performance

Question 2

FiO2 depends on two factors:

Answer 2

1) O2 flow rate
2) Patient’s ventilation (respiratory rate & tidal volume)

Question 3

For a given O2 flow rate, higher ventilation results in ________ FiO2 delivered to the patient

Answer 3

Lower
• because of dilution of 100% O2 (delivered from flowmeter) with 21% O2 (from atmosphere)

Question 4

What are examples of low flow O2 equipments? (3)

Answer 4

1) Nasal cannula
2) Simple face mask
3) Reservoir masks
- partial rebreathing
- non rebreathing

Question 5

Nasal Cannula
What is the:
1) Flow rate range
2) FiO2 range?
3) At flow rates greater than 10L/min may achieve FiO2 of?
4) Complications (2)
5) Pros (5)

Answer 5

1) Flow rate range: 1-4L/min
2) FiO2 range: 21-38%
3) FiO2: 40-50%
4) • Perforation of nasal septum with non humidified O2 use
• Flow > 5L/min causes discomfort
5)
• More comfortable than face mask
• Can eat and drink
• Speech not muffled
• No rebreathing
• Comfortable for long periods of use

Question 6

Simple mask:
1) Flow rate range
2) FiO2 range?
3) Min. Flow of O2 required to avoid rebreathing?

Answer 6

1) O2 flow rate: 5-10L/min
2) FiO2: 30-60%
3) 5L/min

Question 7

In partial rebreathing reservoir mask:
1) What is it’s differentiating feature on the mask?
2) what is in the rebreathed gas?

Answer 7

1) No flap valves
2) Rebreathed gas is dead space component with no CO2

Question 8

What is the feature seen in non rebreathing reservoir mask?
What does this feature allow?

Answer 8

• They have flap valves
(Between bag and mask; and one on mask’s exhalation ports
• Flap valves allow one way flow and prevents rebreathing

Question 9

Reservoir masks:
1) FiO2 range?
2) O2 flow rate?

Answer 9

1) 35-60%
2) 10-15L/min

Question 10

What are examples of High Flow O2 equipments? (2)

Answer 10

1) Venturi mask
2) Mechanical ventilator
- Negative pressure ventilator
- Positive pressure ventilator

Question 11

Venturi masks have Venturi valves which utilizes the principle of __________

Answer 11

jet mixing (Bernoulli effect)

Question 12

Describe the Bernoulli effect in Venturi face mask. (4)

Answer 12

• When O2 passes narrow orifice
• Produces a high velocity stream
• Draws a constant proportion of room air
• Through base of Venturi valve

Question 13

FiO2 range of Venturi mask

Answer 13

24-60%

Question 14

Mechanical ventilation is used to
1)
2)

Answer 14

1) Completely take over respiratory function
2) Support patient’s own respiratory efforts

Question 15

Mechanical ventilation can be divided into: (3)

Answer 15

1) Positive pressure ventilation
2) Negative pressure ventilation
3) Non invasive ventilation

Question 16

Positive pressure ventilation requires:

Answer 16

Artificial airway
• ETT
• Tracheotomy tube

Question 17

How does Positive pressure ventilation work?
How is inspiration triggered?

Answer 17

•Uses positive pressure to force oxygen into patients lungs
•Either by patient or machine