VENTILATOR MODES

Question 1

VC/AC - VOLUME CONTROL/ASSIST CONTROL

Answer 1

Ventilation that delivers a set VOLUME target with variable pressure. As volume increases, pressure decreases (and vice versa).
Settings: Vt, Fi02, PEEP, RR, Ti, Peak flow

Pros: stable Vt and minute vol
Cons: may cause asynchrony, variable peak pressure, may lead to excessive ventilation/resp alkalosis, increased chance of barotrauma.

Question 2

PC - PRESSURE CONTROL

Answer 2

Ventilation that delivers a set PRESSURE target with variable volume.
Settings: FiO2, PEEP, RR, Pressure Support (PS)/Pinsp, Ti
- may also include Pramp

Pros: better synchrony, less risk of barotrauma
Cons: could lead to inadequate tidal volumes (ensure alarms are set)

Question 3

SIMV - Synchronized intermittent mandatory ventilation

Answer 3

A form of ventilation that allows for spontaneous breathing that has a set PRESSURE support (PS). Sometimes referred to as “weaning” mode. When breathing spontaneously, pt takes over WOB.
Settings: Vt, RR, FiO2, PEEP, PS

• Spontaneous breaths: pt determines volume, PS assists in taking longer breaths. RR used for backup/apnea
• No spontaneous breaths: acts like VC (set Vt delivered)

Question 4

PS - PRESSURE SUPPORT

Answer 4

A form of ventilation that allows for spontaneous breathing. PRESSURE support is set, volume is variable.
Pt determines RR.
Settings: FiO2, PEEP, PS. Should have RR backup rates for periods of apnea.

• More frequently used for SBT than SIMV with settings of PS 10, PEEP 5.

Question 5

PRVC - PRESSURE REGULATED VOLUME CONTROL

Answer 5

A dual mode of ventilation that has a set PRESSURE but also ensures a set VOLUME is achieved.
Settings: RR, FiO2, PEEP, target volume

• Operates similar to PC, with the addition of reaching a target volume
• Adjustments are automatically made slowly over time
  Pros: may assist with CO2 elimination, good mode for ARDS, ensures adequate tidal vol met
  Cons: may increase WOB

Question 6

APRV - AIRWAY PRESSURE RELEASE VENTILATION

Answer 6

A form of pressure control, where prolonged periods of high pressure alternate with short periods of pressure release (akin to CPAP). It results in significant recruitment of alveoli and increases Pmean (airway pressure).
Settings: FiO2, P high, P low (pressure; T high, T low (time at pressure).