mechanical ventilation part two
Post on 11-Apr-2017
2 Views
Preview:
TRANSCRIPT
MECHANCIAL VENTILATIONRESPIRATORY CYCLE (PART TWO)
RESPIRATORY CYCLE
Objectives:
• Examine the phases of the respiratory cycle:– Trigger– Inspiratory Phase– Cycling Mechanism– Expiratory Phase
TRIGGER
Time Trigger: no patient effort (no dip: no change
in flow or pressure) followed by a controlled
breath
Flow Trigger: patient effort (dip: a change in flow or pressure) followed by an assisted or spontaneous
breath (depending on mode – see below)
The trigger allows the inspiratory phase to begin:
INSPIRATORY PHASE• During the inspiratory phase positive
pressure is delivered to the lungs.
• The inspiratory phase lasts between .8 seconds to 2 seconds.
• The inspiratory phase is adjusted by the RT depending upon the clinical situation.
CYCLING MECHANISM
• Volume cycled (or limited) will end the inspiratory phase at a set volume (i.e. 500cc).
• Pressure cycled (or limited) will end the inspiratory phase at a set pressure (i.e. 30 cmH20).
• Flow/Pressure cycled (or limited) will end the inspiratory phase at a preset set pressure (i.e. 30 cmH20) or flow (i.e. <15 lmp). Which ever one come first.
CYCLING MECHANISM
500cc
30cm H20
30cm H20 OR <15
lpm
The inspiratory phase ends, or cycles, at a preset volume, pressure, or flow/pressure.
The RT will adjust these parameters depending upon the clinical situation.
EXPIRATORY PHASE• The expiratory phase begins when the inspiratory phase ends.
• The RT can manipulate various setting to increase or decrease the expiratory phase.
RESPIRATORY CYCLE
Let us review:
• The trigger marks the start of the inspiratory phase.
• Positive pressure is applied to the lungs during the inspiratory phase.
• The inspiratory phase lasts between .8 and 2 seconds.
• The inspiratory phase ends (or cycled) at a preset volume (vT), pressure (cmH2O) or flow (lpm).
• At the end of the expiratory phase the ventilator is ready to start another respiratory cycle.
Trigger Inspiratory Phase Cycling Expiratory
Phase
MECHANCIAL VENTILATION• How dose all this fit?
• AC-VC indicates that the ventilator will deliver a combination of assisted and controlled breaths (AC).
• The inspiratory phase will end or be cycled at pre-set volume (VC)
• Assist Control – Volume Cycled (AC-VC) is also know as CMV and VC.
• AC-PC indicates that the ventilator will deliver a combination of assisted and controlled breaths (AC).
• The inspiratory phase will end or be cycled at a pre-set pressure (PC).
• Assist Control – Pressure Cycled (AC-PC) is also know as PCV or PC.
MECHANICAL VENTILATION
• PSV indicates the ventilator will deliver only patient triggered spontaneous breaths.
• The inspiratory phase will end when the flow decreases or the maximum pressure is achieved.
MECHANICAL VENTILATION
• You are doing great!
• We understand how the trigger, inspiratory phase and the three breath types are used to build AC-VC, AC-PC and PSV.
• Next, we will cover how mechanical ventilation can improve oxygenation!
top related