Trigger/Limit/Cycle/Baseline Mechanical Ventilation

Trigger All breaths on a ventilator need to be triggered

Trigger All breaths on a ventilator need to be triggered They can be Time triggered

Trigger All breaths on a ventilator need to be triggered They can be Time triggered Patient triggered

Trigger All breaths on a ventilator need to be triggered They can be Time triggered Patient triggered Flow triggered

Trigger All breaths on a ventilator need to be triggered They can be Time triggered Patient triggered Flow triggered Pressure triggered

Time triggering Time triggering means the ventilator starts the breath

Time triggering Time triggering means the ventilator starts the breath This will happen when there is no patient effort

Time triggering Time triggering means the ventilator starts the breath This will happen when there is no patient effort This is based on the set respiratory rate

Patient Triggering A breath can be triggered by the patient

Patient Triggering A breath can be triggered by the patient Flow triggering is the most common

Patient Triggering A breath can be triggered by the patient Flow triggering is the most common Pressure triggering is another option

Flow Triggering Flow triggering starts with a base flow This flow is continuously flowing through the circuit

Flow Triggering Flow triggering starts with a base flow This flow is continuously flowing through the circuit The ventilator knows how much flow is going through the circuit The liter flow leaving the ventilator should be the same as the liter flow coming back

Flow Triggering As the patient inhales some of the flow goes into the patient lungs This means less flow is returning to the ventilator The ventilator senses that as a patient effort and starts a breath

Flow Triggering The difference in the flow coming out of the ventilator and coming back to the ventilator is how sensitivity is determined The less flow needed to be deflected by the patient the more sensitive it is The more flow needed to be deflected by the patient the more difficult it is to trigger, i.e. less sensitive

Flow Triggering 10 lpm is leaving the ventilator 10 lpm is returning to the ventilator As a patient inhales and takes in 2 lpm 8 lpm is returning to the ventilator This reduction in returned flow tells the ventilator to start a breath

Flow Triggering If you increase the amount of flow needed to be inhaled by the patient the less sensitive the machine is 10 lpm is leaving the ventilator 10 lpm is returning to the ventilator As a patient inhales and takes in 4 lpm 6 lpm is returning to the ventilator

Pressure Triggering Negative pressure is generated when a patient inhales

Pressure Triggering Negative pressure is generated when a patient inhales This negative pressure is in both the patients lungs and the ventilator circuit

Pressure Triggering Negative pressure is generated when a patient inhales This negative pressure is in both the patients lungs and the ventilator circuit The ventilator senses the negative pressure as a patient effort and starts a breath

Pressure Triggering So the patient needs to generate -2cmH2O to start a breath If you increase the amount of negative pressure needed the more difficult it is for the patient to trigger, i.e. less sensitive

Limiting Limiting is what contols are in effect during the inspiratory phase

Limiting Limiting is what contols are in effect during the inspiratory phase After a breath is initiated certain limits will be in effect depending on which type of breath is being delivered

Limiting Limiting is what contols are in effect during the inspiratory phase After a breath is initiated certain limits will be in effect depending on which type of breath is being delivered Limiting factors are what define a type of breath

Limiting Limiting is what contols are in effect during the inspiratory phase After a breath is initiated certain limits will be in effect depending on which type of breath is being delivered Limiting factors are what define a type of breath The two most common limits are

Limiting Limiting is what contols are in effect during the inspiratory phase After a breath is initiated certain limits will be in effect depending on which type of breath is being delivered Limiting factors are what define a type of breath The two most common limits are Pressure

Limiting Limiting is what contols are in effect during the inspiratory phase After a breath is initiated certain limits will be in effect depending on which type of breath is being delivered Limiting factors are what define a type of breath The two most common limits are Pressure Flow

Pressure Limited Pressure limited breaths have a set peak airway pressure

Pressure Limited Pressure limited breaths have a set peak airway pressure The pressure in the patients lungs will not go over the set pressure

Pressure Limited Pressure limited breaths have a set peak airway pressure The pressure in the patients lungs will not go over the set pressure The following breaths are pressure limited

Pressure Limited Pressure limited breaths have a set peak airway pressure The pressure in the patients lungs will not go over the set pressure The following breaths are pressure limited PCV PSV PRVC

Pressure Limited Pressure Control Ventilation (PCV) Pressure is set with the intention of reaching the peak pressure and holding the pressure for part of the inspiratory time

Pressure Limited Pressure Control Ventilation (PCV) Pressure is set with the intention of reaching the peak pressure and holding the pressure for part of the inspiratory time Pressure Support Ventilation (PSV) Pressure is set to augment a patients own tidal volume

Pressure Limited Pressure Control Ventilation (PCV) Pressure is set with the intention of reaching the peak pressure and holding the pressure for part of the inspiratory time Pressure Support Ventilation (PSV) Pressure is set to augment a patients own tidal volume Pressure Regulated Volume Control (PRVC) Pressure changes with each breath with the intention of reaching a specific volume

Flow Limited Flow limiting is used when a specific volume needs to be delivered

Flow Limited Flow limiting is used when a specific volume needs to be delivered Each breath has a rigid flow rate and pattern that will deliver the specific volume

Flow Limited Flow limiting is used when a specific volume needs to be delivered Each breath has a rigid flow rate and pattern that will deliver the specific volume Therefore the breath is limited to a predetermined flow Volume Control is a type of flow limited breath

Pressure vs. Flow Limiting Pressure limited breaths have a variable flow which allows better gas distribution

Pressure vs. Flow Limiting Pressure limited breaths have a variable flow which allows better gas distribution The pressure is limited therefore if lung conditions change the volume will change

Pressure vs. Flow Limiting Pressure limited breaths have a variable flow which allows better gas distribution The pressure is limited therefore if lung conditions change the volume will change If lungs become stiffer the volume will go down as the pressure remains the same

Pressure vs. Flow Limiting Flow limiting will deliver a volume no matter what the lung conditions

Pressure vs. Flow Limiting Flow limiting will deliver a volume no matter what the lung conditions Volume will be consistent but pressures will change

Pressure vs. Flow Limiting Flow limiting will deliver a volume no matter what the lung conditions Volume will be consistent but pressures will change If the lungs become stiffer the pressures will go up

Pressure vs. Flow Limiting PRVC uses pressure limiting but will automatically adjust the pressure to deliver a volume

Pressure vs. Flow Limiting PRVC uses pressure limiting but will automatically adjust the pressure to deliver a volume So the pressure is not set, the volume is set

Pressure vs. Flow Limiting PRVC uses pressure limiting but will automatically adjust the pressure to deliver a volume So the pressure is not set, the volume is set The ventilator will adjust the pressure to achieve the volume

Pressure vs. Flow Limiting PRVC uses pressure limiting but will automatically adjust the pressure to deliver a volume So the pressure is not set, the volume is set The ventilator will adjust the pressure to achieve the volume This allows for the variable flow which is better for gas distribution

Pressure vs. Flow Limiting PRVC uses pressure limiting but will automatically adjust the pressure to deliver a volume So the pressure is not set, the volume is set The ventilator will adjust the pressure to achieve the volume This allows for the variable flow which is better for gas distribution If the lungs become stiffer the pressures will go up

Cycling Cycling is what determines how the breath will stop and allow the patient to exhale

Cycling Cycling is what determines how the breath will stop and allow the patient to exhale Most breaths are time cycled

Cycling Cycling is what determines how the breath will stop and allow the patient to exhale Most breaths are time cycled Any breath type that requires a set Ti is time cycled These include the following breath types

Cycling Cycling is what determines how the breath will stop and allow the patient to exhale Most breaths are time cycled Any breath type that requires a set Ti is time cycled These include the following breath types PRVC

Cycling Cycling is what determines how the breath will stop and allow the patient to exhale Most breaths are time cycled Any breath type that requires a set Ti is time cycled These include the following breath types PRVC PCV

Cycling Cycling is what determines how the breath will stop and allow the patient to exhale Most breaths are time cycled Any breath type that requires a set Ti is time cycled These include the following breath types PRVC PCV Volume Control

Cycling Flow is also used to cycle a breath off

Cycling Flow is also used to cycle a breath off Pressure Support Ventilation (PSV) is flow cycled

Cycling Flow is also used to cycle a breath off Pressure Support Ventilation (PSV) is flow cycled As the inspiratory flow starts to slow down the ventilator will sense that the lungs are getting full and cycle off allowing the patient to exhale

Cycling Flow is also used to cycle a breath off Pressure Support Ventilation (PSV) is flow cycled As the inspiratory flow starts to slow down the ventilator will sense that the lungs are getting full and cycle off allowing the patient to exhale During that same breath it is being pressure limited

Cycling Flow is also used to cycle a breath off Pressure Support Ventilation (PSV) is flow cycled As the inspiratory flow starts to slow down the ventilator will sense that the lungs are getting full and cycle off allowing the patient to exhale During that same breath it is being pressure limited So pressure is being held in the lungs until the flow slows down at which time the ventilator will release the pressure and the patient exhales

Baseline Baseline is what limits are in effect during exhalation Exhalation is passive The only limit will be added pressure, i.e. PEEP The baseline should be assessed via total PEEP to accurately measure the baseline

Rise Time or Slope Rise time is part of the inspiration so could be considered a limiting factor

Rise Time or Slope Rise time is part of the inspiration so could be considered a limiting factor It is usually not included in the definition of a breath

Rise Time or Slope Rise time is part of the inspiration so could be considered a limiting factor It is usually not included in the definition of a breath Rise time adjusts the initial flow rate of a breath

Rise Time or Slope Rise time is part of the inspiration so could be considered a limiting factor It is usually not included in the definition of a breath Rise time adjusts the initial flow rate of a breath It determines how much time is allowed for the breath to reach the peak flow needed to deliver the breath in the allotted time (Ti)

Rise Time/Slope The less time the Rise time is the faster the breath ramps up to full speed

Rise Time/Slope The less time the Rise time is the faster the breath ramps up to full speed The longer the Rise Time is the slower the breath reaches peak flow

Rise Time/Slope So if you have an inspiratory time of 1 second and you set your Rise Time at 0.2 seconds the peak flow will be reached in 0.2 seconds creating a blast of air at the beginning of the breath

Rise Time/Slope So if you have an inspiratory time of 1 second and you set your Rise Time at 0.2 seconds the peak flow will be reached in 0.2 seconds creating a blast of air at the beginning of the breath If you increase the Rise Time to 0.5 seconds the breath will not reach peak flow until half way through the breath creating a slower overall flow

Rise Time/Slope A short Rise Time may be helpful in patient with high inspiratory demands, such as asthma

Rise Time/Slope A short Rise Time may be helpful in patient with high inspiratory demands, such as asthma A longer Rise Time is usually more comfortable because there is not the blast of air at the beginning

Rise Time/Slope A short Rise Time may be helpful in patient with high inspiratory demands, such as asthma A longer Rise Time is usually more comfortable because there is not the blast of air at the beginning Where it is set is very patient dependent

Inspiratory Cycle Off Inspiratory cycle off is part of the flow cycling breath

Inspiratory Cycle Off Inspiratory cycle off is part of the flow cycling breath Pressure Support Ventilation (PSV)

Inspiratory Cycle Off Inspiratory cycle off is part of the flow cycling breath Pressure Support Ventilation (PSV) Flow cycling is used to end a PSV breath

Inspiratory Cycle Off Inspiratory cycle off is part of the flow cycling breath Pressure Support Ventilation (PSV) Flow cycling is used to end a PSV breath Normal inspiration goes to zero flow and then reverses the flow to exhale

Inspiratory Cycle Off Inspiratory cycle off is part of the flow cycling breath Pressure Support Ventilation (PSV) Flow cycling is used to end a PSV breath Normal inspiration goes to zero flow and then reverses the flow to exhale Because it is difficult to achieve a tight seal on the circuit and patient, it is impractical to require the patient to get to zero flow before exhaling

Inspiratory Cycle Off Inspiratory cycle off is part of the flow cycling breath Pressure Support Ventilation (PSV) Flow cycling is used to end a PSV breath Normal inspiration goes to zero flow and then reverses the flow to exhale Because it is difficult to achieve a tight seal on the circuit and patient it is impractical to require the patient to get to zero flow before exhaling Flow cycling allow the breath to end prior to reaching zero flow

Inspiratory Cycle Off Some ventilators have a preset flow rate that will cycle the PSV breath into exhalation

Inspiratory Cycle Off Some ventilators have a preset flow rate that will cycle the PSV breath into exhalation Some ventilators allow the flow rate to be adjusted

Inspiratory Cycle Off Some ventilators have a preset flow rate that will cycle the PSV breath into exhalation Some ventilators allow the flow rate to be adjusted When setting Inspiratory Cycle Off it is a percentage

Inspiratory Cycle Off Some ventilators have a preset flow rate that will cycle the PSV breath into exhalation Some ventilators allow the flow rate to be adjusted When setting Inspiratory Cycle Off it is a percentage The percentage is based on the peak inspiratory flow achieved during the breath

Inspiratory Cycle Off Some ventilators have a preset flow rate that will cycle the PSV breath into exhalation Some ventilators allow the flow rate to be adjusted When setting Inspiratory Cycle Off it is a percentage The percentage is based on the peak inspiratory flow achieved during the breath The percent is what determines when the breath will release the pressure and allow exhalation

Inspiratory Cycle Off If you set the Inspiratory Cycle Off at 25% the inspiratory breath will end when the flow is 25% of the peak flow during that breath

Inspiratory Cycle Off If you set the Inspiratory Cycle Off at 25% the inspiratory breath will end when the flow is 25% of the peak flow during that breath If the peak flow was 60 lpm the breath will end at 25% of that or 15 lpm

Inspiratory Cycle Off If you set the Inspiratory Cycle Off at 25% the inspiratory breath will end when the flow is 25% of the peak flow during that breath If the peak flow was 60 lpm the breath will end at 25% of that or 15 lpm The higher the % set the sooner the breath will be cycled off

Inspiratory Cycle Off If you set the Inspiratory Cycle Off at 25% the inspiratory breath will end when the flow is 25% of the peak flow during that breath If the peak flow was 60 lpm the breath will end at 25% of that or 15 lpm The higher the % set the sooner the breath will be cycled off This may cut off a patient breath early