Lecture 2 - Ventilatory Support I

Question 1

What causes hypoxaemic RF?

Answer 1

1) Inadequate fresh air reaching gas exchange area
2) Reduced Surface area for gas exchange –> leads to atelectasis
3) Diffusion problems (extraction/utilization)

Question 2

How can you improve PaO2?

Answer 2

1. Improve diffusion
   - O2 therapy - increases FiO2, PatmosO2
2. Increase SA for gas exchange
   - CPAP/PEEP - prevents the alveoli from fully closing

Question 3

Examples of controlled O2 devices

Answer 3

Venturi

Mechanical ventilator

Question 4

Examples of uncontrolled O2 devices

4

Answer 4

Simple face mask
High concentration mask
Tracheostomy mask
Nasal catheter/high flow humidified

Question 5

What are the dangers of O2 therapy

4

Answer 5

1. Absorption atelectasis (when the O2 gets used up - no nitrogen - so the airway collpases)
2. FIre
3. Toxicity if FiO2 > 0.7 for >1-2 days
4. Reduced matching of blood+gas d/t hypoxia induced vasodilation

Question 6

To prevent complications from O2 therapy, keep FiO2 < ?

Answer 6

0.6

Question 7

why do you put a person on ventilatory support?

Answer 7

1) assist in respiration - gas movement

2) to improve oxygenation

Question 8

What is CPAP and what does it do?

Answer 8

Continuous Positive Airway Pressure

• pressure positive at the mouth during both inspiration and expiration - splinting effect on airways
• used for spontaneous breaths
• used on people with obstructive sleep apnoea

Question 9

What is PEEP and what does it do?

Answer 9

Positive End Expiratory Pressure

• the airway pressure on expiration reduces alveolar emptying –> increases alveolar size –> increases SA for gas exchange
• Re-expands collapsed alveoli –> increases recruitment –> increases number of alveoli for gas exchange

Question 10

Physio interventions to improve oxygenation

Answer 10

increase SA for gas exchange 
Increase 02 movement 
- meds
- positioning
- MHI, Suctioning, DBE, 
- mobilization