Mechanical and NI Ventilation Flashcards
1
Q
Principles of Mechanical Ventilation
A
- positive pressure ventilation
- delivers “breath” to get O2 in and CO2 out
- gas pumped in during inspiration (Ti)
- patient passively expires (Te)
- Ti + Te = respiratory cycle/”breath”
2
Q
Indications for mechanical ventilation
A
- respiratory failure
- patients at risk of respiratory failure
- unsustainable levels of cardiac work
- unsustainable WOB
- airway protection
- large secretions load
- reversible condition
3
Q
Symptoms showing need for ventilation
A
- spontaneous ventilation inadequate to maintain gas exchange
- PaO2 <60mmHg, PaCO2 >49mmHg
- metabolic cost of breathing increases to 30% (normal 5%)
- other symptoms:
- increased WOB
- accessory muscle use
- sweating
- increased HR/RR/BP
- confusion, aggretion
- secretions
4
Q
Effects of MV
A
- increases gas exchange
- decreases WOB
- improves cardiac function
- allows oxygen to be used by other organs
- multi organ failure
- burns
- sepsis
- improves thoracic stability
- increases alveolar ventilation
5
Q
Controlled mandatory ventilation (CMV)
A
- machine breathes totally for patient
- pt often heavily sedated
- used in OT or very ill patient
- set breaths/min
- causes resp weakness and infection
6
Q
Synchronised intermittent mandatory ventilation (SIMT)
A
- patient takes some breaths, machine takes others
- machine senses when patient is taking a breath
- used in most patients
- set resp rate (decrease as patient improves)
- 3 types of breaths
7
Q
SIMT advantages
A
- improved comfort
- no breath stacking
- reduced resp muscle atrophy
8
Q
SIMT breath types
A
- Controlled
- triggered and delivered by ventilator according to prescribed settings
- Assisted
- triggered by pt
- assisted by ventilator
- same shape as controlled breath
- Spontaneous
- triggered by pt
- assisted by ventilator (PS)
- volume not controlled
9
Q
Assist Control mode
A
- pt receives either Mandatory or Assisted breaths
- pt triggers ventilator
- assisted breath is identical in duration and magnitude as a mandatory breath
10
Q
Pressure Support Breathing (PS/PEEP)
A
- spontaneous breathing by pt
- supported by pressure support and PEEP
11
Q
Advantages of PEEP
A
- reduces bronchiolar and alveolar collapse
- holds open at end of inspiration
- increases FRC
- allows lower FiO2
- reduces shunting
12
Q
Disadvantages of PEEP
A
- reduces cardiac output
- increases airway pressure
13
Q
Pressure Support
A
- augmented pressure during spontaneous breaths
- decreased WOB
- increases tidal volume
- pt initiates breath, PS “lifts up” breath
- pt regulates own tidal volume and resp rate
14
Q
Flowby mode
A
- continuous baseline flow
- reduces dead space
- reduces WOB to trigger a breath
15
Q
Advantages of spontaneous breathing
A
- less disuse atrophy
- decreased weaning time
- less need for sedation
- can exercise and mobilise more easily
- less infection risk
