Mechanical Ventilation

Question 1

Reasons for intubation?

Answer 1

maintain an airway, to supply O2, to protect from aspiration, to enable sedation and paralysis, to rest the respiratory muscles, to facilitate secretion removal.

Question 2

What are the two types of artificial airways?

Answer 2

Endotracheal tubes (ETT) & Nasotracheal

Question 3

Advantages and Disadvantages of endotracheal tubes?

Answer 3

Advantages: allows for short term invasive ventilation, protects the trachea from aspiration, allows route for removal of secretions via suctioning.
Disadvantages: tube can go down R main bronchus causing airway collapse, oesphageal intubation, obstruction by mucous, damage to the larynx

Question 4

Complications of Intubation

Answer 4

• Increase in dead space ventilation
  -Increase airflow resistance
• Reflex bronchoconstriction due to foreign body
• Impaired MCC (trapped sputum → disruption to the cilia)
• Bypass upper airway defence mechanism i.e. increased risk of infections
• Direct trauma to airway leading to oedema (swelling of airway) and erythyma (redness of airways)

Question 5

Reasons for a tracheostomy (4)

Answer 5

1. Bypass obstructed upper airway.
2. Prolong Mechanical Ventilation.
3. Remove secretions from airway
4. Easier and safer delivery of O2 to the lungs due to being closer, therefore less deadpace.

Question 6

Early complications with a tracheostomy

Answer 6

• Bleeding, pneuomothorax, Nerve injuries to the larynx, infection

Question 7

Late complications with a tracheostomy

Answer 7

1. Failure to heal
2. Blocked tracheostomy tube
3. Scarring of trachea leading to stenosis
   - Collapsed trachea due to incorrect inserton.

Question 8

What is the purpose of ventilator classifications?

Answer 8

how the machine knows how much flow to deliver

Question 9

what are the ventilator classifications?

Answer 9

Volume controlled, Pressure controlled and Dual controlled

Question 10

what is triggering?

Answer 10

initiates aspiration on a ventilator

Question 11

what is cycling?

Answer 11

switching from inspiration to expiration. Depending on the mode of ventilation, cycling can be time cycled, pressure cycled , volume cycled or flow cycled.

Question 12

Common modes of invasive ventilation

Answer 12

Controlled mechanical ventilation (CMV)
Assist control ventilation (ACV)
Synchronised intermittent mandatory ventilation (SIMV)
Pressure support ventilation (PSV)

Question 13

What is Synchronised intermittent mandatory ventilation? (SIMV) and who is it used for?

Answer 13

Patient initiated mandatory breath → patients inspiratory effort creates a negative pressure which triggers the ventilator to help deliver a breath.
Mandatory breath will still be delivered if the patient doesn’t try to inspire.
Patient can spontaneously breath in between these breaths
For patients who do not have a constant breathing cycle and still require some support.

Question 14

What is CMV and who is it used for?

Answer 14

Paralysed patients i.e. general anaesthetic. Can be volume controlled or pressure controlled. Volume controlled = preset tidal volume and respiratory rate. Pressure controlled = Fixed respiratory rate and peak airway pressure. Tidal volume will vary with lung compliance and resistance.

Question 15

what is pressure support ventilation?

Answer 15

Method of assisting spontaneous breathing in a ventilated patient.
Patient controls RR and Vt but not the pressure limit.
Patient triggers the ventilator – the ventilator delivers a flow up to a preset pressure limit

Question 16

what is PEEP?

Answer 16

Positive-end-expiratory pressure: maintains a certain level of pressure in the airways at the end of exhalation to keep the alveoli open. Improves gas exchange by preventing alveolar collapse, reducing WOB and improves lung compliance. Lungs are more inflated with helps with ease of breathing. AVG: 5-15

Question 17

Who is eligible for non-invasive ventilation?

Answer 17

Pt has capacity to protect their own airway (not at risk of aspiration)
Conscious and compliant patient
Capacity to manage respiratory secretions (reasonable cough; challenging to do a good cough over the NIV)
Likelihood of tolerating the planned level of support
Likelihood of deterioration and treatment limitations
Potential to recover to a quality of life acceptable to the patient.

Question 18

What is CPAP?

Answer 18

Continuous Positive Airway Pressure delivered via a face mask or an endotracheal tube. Used for type 1 respiratory failure ( CO2 normal and O2 <60)

Question 19

What is BiPAP?

Answer 19

Bilevel positive airway pressure - delivered via facial or nasal mask. Used for T2RF (high CO2, low O2). Helps to removed excess from lungs CO2. provides expiratory and expiratory airway pressure.

Question 20

Reason for NIV:

Answer 20

Acute respiratory distress, with a high work of breathing or difficulty with mucus clearance.
Weaning high-risk patients from mechanical ventilation
Post-extubation management

Question 21

Contraindications for NIV:

Answer 21

absolute: need for tracheal intubation, cardiorespiratory arrest, facial burns, decreased level of consciousness.

relative: copious secretions/vomiting, facial fractures, upper airway surgery, recent upper git surgery

Question 22

Effects of mechanical ventilation?

Answer 22

decreased FRC & mucociliary clearance

Question 23

Role of Respiratory Physiotherapy during Mechanical Ventilation?

Answer 23

Airway secretion clearance (positioning, manual chest techniques, suctioning), Recruitment of lung volume or improvement of atelectasis (positioning, hyperinflation, and deep breathing), Maintenance of oxygenation, and maintenance/improvement of inspiratory muscle strength (inspiratory muscle training devices)