Mechanical Ventilation Flashcards

1
Q

How does anesthesia affect ventilation?

A
  1. Alters CO2 sensitivity
  2. Relaxes respiratory muscles
  3. Develops atelectasis
  4. Worsens V/Q match issues
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How can ventilation affect anesthesia?

A
  1. Uptake depends on ventilation

2. Controlled ventilation facilitates reliable uptake and smooth plane of anesthesia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is ventilation defined by?

A

PaCO2

Patient should have normal resp rate, rhythm and effort

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is oxygenation?

A

Process of oxygenation of arterial blood

Defined by PaO2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is oxygenation monitored by?

A

Arterial blood gas or pulse oximetry

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What does oxygenation depend on?

A

Inspired O2%

100% O2 typically insures good oxygenation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the two phases of respiration?

A

Inspiration and expiration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What does resistance do?

A

Limits flow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What does compliance do?

A

Limits volume

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Indications for mechanical ventilation?

A
  1. Need to decrease PaCO2
  2. Need to increase PaO2
  3. Need to decrease respiratory effort (mostly ICU)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Indication for mechanical ventilation during anesthesia

A
  1. Control of respiratory function
  2. Prolonged anesthesia
  3. Maintain stable anesthesia plane
  4. Neuromuscular blockade
  5. Thoracic surgery, chest wall, hernia
  6. Obesity, increased abdomen pressure
  7. head down positioning
  8. Laparoscopy
  9. Control ICP
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Side effects of MV

A
  1. Impairs venous return and cardiac output
  2. May cause hypotension especially in hypovolemic patients
  3. Pneumothorax and lung injury
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Direct effects of hypercapnia

A
  1. Peripheral vasodilation
  2. Decreased myocardial contractility
  3. Bradycardia and possible arrest
  4. Increased ICP
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Indirect effects of hypercapnia

A
  1. Tachycardia, arrhythmias
  2. Increased myocardial contractility
  3. Increased blood pressure
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

CO2 narcosis levels

A

> 95 mmHg progressive narcosis

>245 mmHg complete narcosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What may happen if not ventilating properly?

A

CO2 accumulation, hypoxemia, sudden death

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Should horses be ventilated?

A

Debated issue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Types of ventilation

A
Spontaneous- patient breathing
Assisted- patient timed, machine assists
Mandatory/Controlled- ventilator controls
Manual- bag
Mechanical- machine driven
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Ventilation modes

A

Volume controlled

Pressure controlled

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What can result from volume ventilation?

A

Pneumothorax if compliance is decreased

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Which ventilation mode is preferred if lung volume changes during a procedure?

A

Pressure controlled

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Which ventilation mode is preferred if trans-pulmonary pressure changes during a procedure?

A

Volume controlled

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Which ventilation mode works well for all patient sizes?

A

Pressure controlled

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Classification of ventilators

A
  1. Source of driving power
  2. Control variable
  3. Cycle variable
  4. Trigger variable
  5. Limit variable
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Source of driving power
1. Electronically driven | 2. Pneumatically driven (pressurized gas)
26
Which source of driving power is more common?
Pneumatically driven
27
Control variables
1. Flow- delivers constant flow | 2. Pressure- delivers constant patient
28
Cycle variables
Triggers expiration when a set value is reached 1. Volume 2. Pressure 3. Time 4. Flow- diminishing flow
29
What is flow variable useful for?
Pressure support ventilation- helps accommodate the patients breathing pattern
30
Trigger variable
Triggers inspiration when a set value is reached 1. Pressure- negative pressure 2. Flow- inpiratory flow
31
Trigger variables are used during what ventilation modes?
Assisted
32
Limit Variable
When value is reached, inspiration will be terminated 1. Volume limit 2. Pressure limit
33
What does a pressure limit prevent?
Barotrauma if ventilator is set inappropriately
34
How can volume controlled ventilation be achieved?
Flow controlled, time cycled ventilator OR Flow controlled, volume limited, time cycled ventilator
35
How can pressure controlled ventilation be achieved?
- Pressure controlled, time cycled ventilator - Pressure controlled, pressure cycled ventilator - Flow controlled, pressure cycled ventilator
36
I:E Ratio
Ratio of inspiratory/expiratory times
37
What does the I:E ratio define?
Tidal volume (Vt)
38
Does the RR affect inspiratory time and Vt?
Nope
39
PIP
Peak inspiratory pressure- inflates alveoli
40
PEEP
Positive end expiratory pressure- keeps alveoli open
41
Indications for PEEP
1. Open thorax 2. Lung parenchymal disease 3. Following alveolar recruitment maneuver
42
Should PEEP be used during routine anesthesia?
Benefits are questionable
43
IMV
Intermittent mandatory ventilation- allowed to breath freely between mechanical breaths
44
SIMV
Synchronized IMV- each spontaneous breath is assisted
45
PSV
Pressure Support Ventilation- patient is breathing freely but supported with pressure Flow termination, better synchrony than SIMV
46
CPAP
Continuous Positive Airway Pressure- assisted ventilation mode when both insp/exp pressures are positive
47
Ventilating healthy lung values
``` Tidal volume : 10-15mL/kg RR: 10-15 bpm Inspiratory time: 1-2sec PIP: 10-20 cmH2O PEEP: 0-2 cmH2O ```
48
Ventilating sick lungs
``` Tidal volume : 4-8mL/kg RR: up to 60 bpm Inspiratory time: may be increased but watch expiration PIP: 35-60max cmH2O PEEP as needed: 5-20 cmH2O ```
49
Which lung typically collapses during anesthetic procedures?
The most dependent one very rapidly after induction
50
Can a collapsed lung persist for hours/days after surgery?
Yes
51
What is cyclic recruitment?
Opening and collapse of alveoli with each breath, may lead to lung injury
52
Mechanisms of atelectasis formation
1. Compression 2. Absorption 3. Lack of surfactant
53
Alveolar recruitment maneuver (ARM)
Therapeutic maneuver aiming to open lung atelectasis and improve oxygenation
54
Types of ARM
CPAP and Cycling Should be followed by PEEP
55
Open Lung concept
Therapeutic approach aiming to reverse atelectasis, prevent cyclic recruitment, and ventilator inducted lung injury ARM followed by optimal PEEP
56
Clinical application of ARM
Safe airway pressures are highly individual variation Should only be performed if you have sufficient monitoring/equipment and clinical indication
57
Patient-ventilator asynchrony
Patient attempts to breath out of phase with the ventilator
58
Common causes of patient-ventilator asynchrony
Inadequate anesthetic depth Inadequate lung volume or tidal volume ICU: pneumothroax, atelectasis, hypotension, hyperthermia
59
Treatment for patient-ventilator asynchrony
Treat underlying cause; may cause rapid deterioration of oxygenation and ventilation
60
Weaning from ventilator after surgery
If a normal healthy animal it's simple Decrease ventilator setting or continue ventilating until fully awake May use opioid antagonists if necessary
61
Weaning from ventilator in the ICU
More difficult since lungs are probably not healthy Spontaneous ventilation trials may be used