Ventilator Flashcards
Ventilator functions
Ventilate patient
Volume Control Ventilation (VCV)
Pressure Control Ventilation (PCV)
Pressure Support Ventilation (PSV)
Synchronized Intermittent Mandatory Ventilation (SIMV)
Oxygenate patient
FIO2
Positive End-Expiratory Pressure (PEEP)
Define: Minute Ventilation
Respiratory Rate x Tidal Volume
Normal range 5-6 L/min
Inspiratory:Expiratory (I:E) Ratio
Normal range 1:2 or 1:3 in COPD patient
Peak Inspiratory Pressure (PIP)/ Peak Airway Pressure (PAP)
The pressure measured by the ventilator in the major airways
Strongly reflects airway resistance
Plateau Pressure
Positive pressure applied to small airways & alveoli
Goal is to keep under 30 cmH2O because excessive alveoli stretch is thought to be a cause of ventilator-induced lung injury
Peak Flow
Determines rate of tidal volume delivery to the patient during mandatory volume control breaths
Affects I:E ratio & peak pressure
Inspiratory Pause (TIP)
- Holds breath at end of inspiration (before exhalation starts)
- Allows breath to diffuse better
- Only available with VCV
- Usually 25% of inspiratory time
- Takes time from inspiration & adds it as a hold (expiration remains same)
Auto-PEEP
- Air trapping in the lungs because of insufficient exhalation time
- Signs
- Non-zero end expiratory pressure
- Increasing PIP/PAP
Positive End Expiratory Pressure (PEEP)
- Constant positive pressure applied at end of exhalation
- Causes airway pressure to not return to 0 cmH2O
Volume Control Ventilation (VCV)
- Set TV, RR, & I:E
- Good initial settings are TV 10 mL/kg, RR = 10, I:E = 1:2 (adjust to get ETCO2 30-35)
- Peak airway pressure (PAP) is variable with each breath
- Waveform - Sloped, Ventilator will provide flow gradually until TV is achieved
- Advantages - guaranteed minute ventilation
- Disadvantages - pt doesn’t trigger breath, may need to reduce tidal volume if get high PIP/PAP
Pressure Control Ventilation (PCV)
- Set peak airway pressure (which equals plateau pressure,) RR, & I:E
- Good initial settings are P = 15 cmH20, RR = 10, I:E = 1:2 (adjust to get ETCO2 30-35)
- TV is variable with each breath (increase P will increase TV)
- Advantages:
- Limiting the peak inflating pressure delivered by the ventilator will limit the transalveolar pressure produced, thereby reducing ventilator-induced lung injury.
- The decelerating flow used to produce PCV is thought to improve the distribution of gas flow.
- When compared with volume control ventilation, there is a more rapid improvement in lung compliance and oxygenation
- Disadvantages:
- pressure control does not guarantee minute ventilation, and therefore requires more monitoring by the operator
PIP vs Plateau Pressure
- Volume Controlled Ventilation
- PIP is determined from tidal volume set
- Plateau Pressure is determined by applying an inspiratory hold (0.5-1 sec). Hold represents no flow, which gives pressure the alveoli are seeing
- Pressure Controlled Ventilation
- PIP usually same as Plateau Pressure because of how breath is delivered
- There is an inherent inspiratory pause
Pressure Support Ventilation (PSV)
- method of assisting spontaneous breathing in a ventilated patient. It can be used as a partial or full support mode
- Independent Variables: support pressure, inspiratory time, flow trigger, FIO2, Peep
- Dependent Variables: Tidal Volume, Respiratory rate
- Advantages: pt breathing spontaneously, can augment TV
- Disadvantages: requires pt to breath spontaneously
Synchonized Intermettent Mandatory Ventilation (SIMV)
- Breaths are given at preset time intervals
- Patient can breathe spontanously between the ventilator breaths
- Ventilator will not give a breath if the patient inspires at that same instant
- This is VCV sychronized patient breathing
- Independent Variables - TV, RR, I:E, FIO2, Pressure support level, PEEP (optional)
- Dependent variables (vary per breath) - PIP, Plateau pressure
- Can be used as a way to start building up CO2
- Disadvantages - may confuse pt becuase not physiological to breathe spontaneously and receive postitive ventilation breaths
Which ventilation mode utilizes a decelerating flow pattern?
PCV