Introduction to critical care

Question 1

What is the role of a mechanical ventilator?

What is invasive ventilation?

Answer 1

The ventilator assist or replace the function of the inspiratory muscles by delivering gas to the lungs under positive pressure
Supportive not curative.
Invasive ventilation = mechanical ventilation via artifical airways (endotracheal intubation or tracheostomy tube)

Question 2

Give some indications for mechanical ventilation

Answer 2

1. Respiratory failure
   - severe hypoxaemia from lung disease
2. Able to breath adequately but is deemed inadvisable
   - acute brain injury and pt is sedated
3. Require intubation for airway protection
4. Airway obstruction
   - tumour

Question 3

What is an Endotracheal tube (ETT)?

Answer 3

Flexible plastic tube that is placed through the mouth into the trachea to help a pt breath. Then connected to a ventilator which delivers O2 to the lungs.

Question 4

Give some advantages and disadvantages for cuffed ETTs

Answer 4

Advantages:
- protects airway in prescence of copious secretions
- establishes seal for ventilatory support
- greater ease of intubation
Disadvantages:
- mucosal damage

Question 5

Give some indications for intubation

Answer 5

• pt unable to maintain their airway

- may be too sick or injured to provide enough O2 to the body without assitance

Question 6

Give some risks of intubation

Answer 6

• trauma to teeth, mouth and/or larynx
• trauma to trachea
• bleeding
• aspirating (breathing in) vomit or saliva
• pneumonia is aspiration occurs
• sore throat

Question 7

What are the average ETT sizes for adult males and females?

Answer 7

Adult female = 7-8mm

Adult male = 8-8.5mm

Question 8

Why should an ETT be secured (what happends if it moves)?

Answer 8

If it slips down it can enter the right main bronchus so left lung is not ventilated
If it slips up and passes back past the larynx the pt is not being ventilated

Question 9

Give some indications for a tracheostomy

Answer 9

• more comfortable than an ETT
• allows speaking and normal breathing
• can reduce duration of ventilation and length of stay
• allows mobility and rehab

Question 10

What are some complications of tracheostomy

Answer 10

• providea a gateway for ventilator associated pneumonia

- loss of warming and humidifying functions of the nose and upper airway leading to thich secretions and ciliary damage

Question 11

Briefly describe the process of inserting a tracheostomy.

Answer 11

An incision is made into the trachea below the larynx thorugh the skin and through the 2nd, 3rd and 4th tracheal ring. A small hole is made in the fibrous tissue of the trachea and the opening is then dilated to allow air intake.

Question 12

Briefly describe a dual cannula tracheostomy

Answer 12

Outer cannula:
- hold the tracheostomy open
- has holes to attach cloth ties or velcro
Inner cannula:
- disposable or reusable
- locked in place to avoid being coughed out

Question 13

Give some pros and cons of dual cannula tracheostomies

Answer 13

Pros:
- removal of inner cannula allows quick restoration of airway should tube become blocked
- useful for pts with sputum, as it can be removed and cleaned
Cons:
- narrows internal diameter of the tracheostomy
- increases pts WOB
- Regular cleaning needed (4 hourly)

Question 14

What is a fenestared tracheostomy

Answer 14

Single large or multiple openings in posterior walll if outer tracheostomy cannula
Allows additional airflow thorugh airway and over the vocal cord.
Often used on pts who are being weaned from the tracheostomy.

Question 15

What does humidification help with?

Answer 15

Having a trachea tube by-passes the humidification mcchanisms, so they must be provided to keep secretions thin and to avoid a mucus plug.

• avoids atelectasis
• avoids obstruction of major airways
• avoids trachea tube blockages