EXAM #2: MECHANICAL AND NONMECHANICAL VENTILATION

Question 1

What are the indications for mechanical ventilation?

Answer 1

1) Airway protection
2) ARDS
3) Shock
4) NM disorder
5) Respiratory/cardiac arrest
6) Acute elevation in ICP
7) Tachy or bradypnea
8) Respiratory acidosis

Question 2

What lung units are poorly ventilated on mechanical ventilation?

Answer 2

Inferior and dependent lung units

*Gases are preferentially delivered to the anterior lung units with least resistance

Question 3

How did the iron-lung work?

Answer 3

Negative pressure developed in the environment of the apparatus

*Did not move the diaphragm; therefore, it didn’t work very well

Question 4

What is the difference between a mandatory and spontaneous breath on the ventilator?

Answer 4

Mandatory= ventilator will generate a pre-set number of breaths at a certain volume/pressure

• “Controlled”= initiated by the ventilator
• “Assisted”= patient effort initiates

Spontaneous= patient effort dictates INITIATION AND DURATION of breath

Question 5

What are the three T’s to keep in mind when setting a ventilator?

Answer 5

1) Target (control)= aspect of inspiration that is primarily controlled by the ventilator
- Volume ( or “flow”)
- Pressure
2) Trigger= signal to initiate the breath
- Time
- Pressure
- Flow
3) Termination (cycling)= criteria that signals the end of the breath
- Volume
- Flow
- Time

Question 6

What is a volume targeted breath?

Answer 6

Also known as “flow,” this is when the volume/flow of inspiration is the main variable controlled by the ventilator

*Airway pressure is variable in volume targeting

Question 7

What is a pressure targeted breath?

Answer 7

This is when airway pressure is the main variable targeted during inspiration

*Tidal volume is and flow are variable

Question 8

What is the most common mode of ventilator setting?

Answer 8

Assist control mode

Question 9

What is the assist control mode?

Answer 9

• This is a mix of mandatory and fully assisted breaths, such that each breath gets the same tidal volume
• Can be pressure or volume targeted

*Generally, most commonly accepted; minimizes patient work of breathing

Question 10

What are the disadvantages of assist control mode?

Answer 10

1) Can result in high minute ventilation and respiratory alkalosis
- Remember, control + assisted breaths get full support
2) Possible hyperinflation/barotrauma

Question 11

What is intermittent mandatory ventilation or SIMV?

Answer 11

This is a mix of mandatory breaths, plus partially supported spontaneous breaths from the patient

*AC= spontaneous breaths outside mandatory are FULLY supported 
SIMV= spontaneous breaths outside mandatory are PARTIALLY supported

Question 12

What is spontaneous ventilation (PSV)?

Answer 12

In this mode, there are NO MANDATORY BREATHS
- Patient initiated breaths are supported to a certain pressure

*Most comfortable mode for alert patient

Question 13

What is the utility of PSV?

Answer 13

Used to determine if a patient is ready to come off the ventilator

Question 14

How can you improve oxygenation in a patient on a ventilator?

Answer 14

1) Increase FiO2
2) PEEP
3) Increased inspiratory time

Question 15

What are the drawbacks to increased airway pressure?

Answer 15

1) Increased deadspace from overdistended alveoli
2) Decreased venous return, CO, oxygen delivery from increased intrathoracic pressure
3) VALI from overstretching alveoli
4) Barotrauma

Question 16

What determines PCO2 on the ventilator?

Answer 16

• Minute ventilation i.e. TV x RR

- Increased minute ventilation causes a DECREASE in PCO2

Question 17

What is the normal TV for a patient on a ventilator? How does this change for a patient with ARDS?

Answer 17

6-8ml/kg/IBW

*This DECREASES in ARDS

Question 18

In a patient with ARDS, how do TV vent. setting need to be changed?

Answer 18

ARDS= 4-6ml/kg/IBW

Question 19

What is the goal for plateau pressure in the adult patient on a ventilator?

Answer 19

Less than 30 cm H20

Question 20

What is the target pH for a patient on a ventilator?

Answer 20

Greater than 7.1

Question 21

What are the ABCDEFs of ventilator liberation?

Answer 21

A= Assess and manage pain 
B= Breathing trial daily 
C= Choice of analgesics/sedation 
D= manage Delerium 
E= Early mobilization/exercise 
F= family engagement

Question 22

What are the criteria for liberation?

Answer 22

1) Improving clinical status
2) Stable
3) Awake and interactive
4) Secretions controlled
5) Normal oxygenation

Question 23

Roughly what ratio of patients have to be re-intubated after they are taken off the vent.?

Answer 23

1/5

Question 24

What is the difference between difficult and prolonged liberation from the vent.?

Answer 24

Difficult= 1-3 failures in first 7x days

Prolonged= on vent. for more than 7x days

Question 25

What procedure can help prevent failure of liberation?

Answer 25

BiPAP or non-invasive ventilation (NIV), early after extubation

Question 26

What are the indications for NIV?

Answer 26

1) AECOPD
2) CHF
3) NM Failure
4) Pneumonia immunocompromised

Question 27

What are the contraindications to NIV?

Answer 27

1) Comatose/ somnolent
2) Increased secretions
3) Bleeding
4) Vomiting
5) ARDS
6) Unstable/shock
7) Cannot wear mask

Question 28

What are the indications for high flow nasal cannula oxygen?

Answer 28

1) Hypoxic respiratory failure
2) Claustrophobia
3) Intolerant of NIV
4) Palliation

Question 29

What are the contraindications to high flow nasal cannula oxygen?

Answer 29

1) Shock
2) Hypercapnia
3) NM resp. failure
4) Tachypnea
5) Inability to protect airway

Question 30

What is ECMO/ECLS?

Answer 30

Extracorporeal Membrane Oxygenation vs. Extracorporeal Life Support

This is a temporary means of taking over heart/lung function, giving those organs time to recover

Question 31

What are the indications for ECMO?

Answer 31

1) Consider ECMO/ECLS if PF ratio less than 150 in ARDS

2) Start ECMO/ECLS if PF ratio is less than 100 in ARDS

Question 32

What are the contraindications to ECMO/ECLS?

Answer 32

1) Condition incompatible with life after recovery
2) Pre-existing conditions
3) Age/size?
4) Futility
5) Lethal chromosome abnormalities
6) More than 60% TSA grade III burn

Question 33

What is the major risk associated with ECLS?

Answer 33

Bleeding