Lecture 3 - Ventilation full

Question 1

What is ventilation?

Answer 1

Air entering the lungs

Question 2

Why might you use non-invasive ventilation (think as a clinical consideration rather than for what specific conditions)

Answer 2

• To avoid invasive ventilation
• To wean someone off invasive ventilation
• As a therapeutic trial with a view to invasive ventilation if it fails
• For long term respiratory support

Question 3

Would non-invasive ventilation be used for someone in type 1 or 2 respiratory failure?

Answer 3

Type 2 respiratory failure (but with a pH higher than 7.1)

Question 4

What is CPAP?

Answer 4

Controlled positive airway pressure
- Sustained positive pressure applied

Question 5

How does CPAP prevent atelectasis

Answer 5

Maintains airway pressure (PEEP) in order to enable collateral ventilation and keep the alveoli open preventing atelectasis

Question 6

What is BiPAP?

Answer 6

Bilateral positive airway pressure
- IPAP during inspiration
- EPAP during exhalation

Question 7

What are volume and pressure models of ventilation

Answer 7

Volume delivers a consistent tidal volume whereas pressure based systems achieve a varied tidal volume based on airway resistance and lung compliance

Question 8

How does airway resistance and lung compliance impact the tidal volume achieved using a pressure based system of ventilation?

Answer 8

Airway resistance - as airway resistance increases, the same pressure will achieve a lower tidal volume

Lung compliance - as lung compliance increases, the same pressure will achieve a higher tidal volume

Question 9

Would you choose volume or pressure based ventilation for patients with obstructive and restrictive lung diseases?

Answer 9

Restrictive = volume

Obstructive = pressure

Question 10

Give some comparisons in set up and running of volume and pressure based ventilation systems

Answer 10

Volume = more complex to set up, heavier and larger in size

Pressure based systems enable you to select a max IPAP

Volume systems have poor leak compensation compared to pressure based systems

Question 11

What are some contraindications and precautions of Non-invasive ventilation methods?

Answer 11

Severe hypotension
Undrained pneumothorax
Severe bullous lung disease
Cardiac arrythmias
Neurological instability
Recent lung or upper GI surgery
Facial trauma
Extreme anxiety

Question 12

What are some complications of non-invasive ventilation?

Answer 12

Tissue necrosis due to pressure sores caused by masks
Gastric distention (air going into stomach)
Air leaks
Claustrophobia
Impact sleep quality and cause fragmentation
Can cause people to retain secretions

Question 13

How does BiPAP prevent rebreathing of CO2?

Answer 13

All exhaled air containing CO2 is pushed out of exhalation port before next inspiration as greater pressure is produced in IPAP for inhalation

Question 14

What is invasive ventilation used for?

Answer 14

Reversible organ/multi-organ failure
When someone is sedated
To protect the airway
Trauma
Post surgery
People who score very low on GCS

Question 15

What is support mode in invasive ventilation?

Answer 15

Assists with the patient’s breathing and helps to decrease work of breathing

Question 16

What is controlled mode in invasive ventilation?

Answer 16

Completely takes over ventilation for the patient

Question 17

What is pressure assisted invasive ventilation?

Answer 17

Pressure is increased to aid ventilation

Question 18

What is volume assisted invasive ventilation?

Answer 18

Aim is to achieve a set tidal volume

Question 19

What does assist-control mode mean?

Answer 19

That the volume is preset and the patient triggers the breath

Question 20

What does pressure support ventilation mean?

Answer 20

Pressure is preset
The machine ventilates the patient fully

Question 21

What does pressure controlled ventilation mean?

Answer 21

Pressure is preset
Patient triggers the breath

Question 22

Describe three parameters you need to set on ventilation machines and what they mean

Answer 22

You can set the resp rate in control mode and you can set a back up rate in support mode for if the patient’s resp rate falls too low

Ratio of timings - how long you breathe in for compared to out

Flow - the flow at which air is delivered, gradually increased towards peak inspiration

Question 23

What is type 1 respiratory failure

Answer 23

When PpO2 is below 8KPa but CO2 is within normal range

Question 24

What is the cause of Type 1 respiratory failure

Answer 24

A V/Q mismatch

Question 25

What is acute type 2 respiratory failure?

Answer 25

PpO2 is below 8KPa
PpCO2 is above 6KPa
Base excess and PpHCO3- are normal
pH is below 7.35

Question 26

What is chronic type 2 respiratory failure?

Answer 26

PpO2 is below 8KPa
PpCO2 is above 6KPa
Base excess and PpHCO3- are out of range
pH is normal

Question 27

What is acute on chronic type 2 respiratory failure?

Answer 27

PpO2 is below 8KPa
PpCO2 is above 6KPa
Base excess and PpHCO3- are out of range
pH is below 7.35

Question 28

What is type 2 respiratory failure always caused by?

Answer 28

Ventilatory failure

Question 29

What do load and capacity refer to?

Answer 29

Load - the requirement of the ventilatory/respiratory system, if load is increased and exceeds capacity this can lead to respiratory failure

Capacity - The ability of the body to meet respiratory demands (respiratory muscles, neural control, physiology of the lungs etc). If any of these aspects mean the capacity for ventilation is reduced below the load, the body will be in deficit leading to respiratory failure