Principles of Mech Vent Flashcards
3 elements in Vt delivery
Breath is triggered
Gas flow
Ventilator cycles off
in this setting,
volume is delivered equally each fraction of inspiratory time
constant FLOW RATE
volume triggered
INspiratory gas flow in pressure targeted setting depends on _______ pressure
airway pressure at the trachea and alveoli
Expiratory pressure generator
PEEP
In this type of flow setting, Vt is predetermined and fixed ( independent of peep)
Volume controlled
aside from tidal volume, what else is fixed in volume controlled setting
Inspiratory time
what is the FLOWN wave pattern in volume control
Square wave
Advantage of pressure control
Increased MAP
Increases alveolar recruitment duration
Protect agains barotrauma
Allows for a significant leak
Advantage of volume control
Stable minute ventilation
Initial flow rate is LOWER
(If airway resistance is HIGH)
Diasdvanate of PC
Uncontrolled volume may result to volutrauma
Tidal volume depends on respiratory compliance
In PC, the flow (volume) of gas, depends on the pressure difference of ______,
And DIMINISHES over time —> “Decelerating ramp flow”
Gas source (ventilator) and
Gas destination (alveoli)
What changes the flow or can alter the flow in PC
Change in compliance, resistance, patient effort
*not the pressure
Initiation and termination of a PC breath depend on _______
Timing (rate)
Duration of itime
*set on the vent
pressure and principles of flow are the same as PC bur the initiation of breath needs to be triggered by inspiratory effort of the patient
Pressure support
In PS, termination of inspiration happens when insp flow rate falls
20-30% of the initial flow rate
vent provides all the work
CMV
breath initiated by the patient and vent completes the breath
with minimum (back up) breaths per minute
AC
weaning is difficult
intermittent mandatory breaths based on the set minute vent
px can make their own breaths not altered
IMV
better patient vent synchrony
SIMV
High flow can deliver up to how many ml per min gas flow
8L/min in an infant
60 L/min large child
peep of high flow
2-5
Continuous distending pressure
small vts at a rapid rate
High frequency vent
HFOV hz and bpm
600-900 bpm
10-15 Hz
major use of HFOV
lung recruitment
