NIV

Question 1

Describe CPAP with regards to pressure during inspiration and expiration; what is CPAP mainly used for?

Answer 1

• constant single level during insp/exp

- mainly for HYPOXAEMIC RF

Question 2

Descirbe the physiological effects of CPAP

Answer 2

1. Increases FRC by opening collapsed or underventilated alveoli
2. Increases PaO2
3. Stabilises airway collapse
   - d/t +ve pressure during exp splinting the airways open
4. Reduces WOB

Question 3

What are the risks of CPAP?

Answer 3

Overinflation

Increased alveolar deadspace (pressure pushes deadspace air closer to alveoli)

Question 4

What are teh characteristics of bilevel ventilation

Answer 4

2 levels of support: IPAP (pressure support) and EPAP (CPAP)
Used for HYPERCAPNIC RF

IPAP:

• actively assists insp and increases Vt
• reduces WOB
• reduces CO2

EPAP:
- improves lung volumes and oxygenation

Question 5

What is HFNC used for?

Answer 5

Increasingly used for hypoxemia over CPAP

Consists of:

• air/o2 blender
• humidifier
• heated circuit
• nasal cannula

Question 6

What are the physiological effects of HFNC?

Answer 6

1. Reduces deadspace - gets behind the deadspace air and pushes it out
2. Small amounts of PEEP to increase FRC
3. Humidification =