Trigger/Limit/Cycle/Baseline

Trigger/Limit/Cycle/BaselineMechanical VentilationTriggerAll breaths on a ventilator need to be triggeredTriggerAll breaths on a ventilator need to be triggeredThey can beTime triggeredTriggerAll breaths on a ventilator need to be triggeredThey can beTime triggeredPatient triggeredTriggerAll breaths on a ventilator need to be triggeredThey can beTime triggeredPatient triggeredFlow triggeredTriggerAll breaths on a ventilator need to be triggeredThey can beTime triggeredPatient triggeredFlow triggeredPressure triggeredTime triggeringTime triggering means the ventilator starts the breathTime triggeringTime triggering means the ventilator starts the breathThis will happen when there is no patient effort

Time triggeringTime triggering means the ventilator starts the breathThis will happen when there is no patient effortThis is based on the set respiratory ratePatient TriggeringA breath can be triggered by the patientPatient TriggeringA breath can be triggered by the patientFlow triggering is the most commonPatient TriggeringA breath can be triggered by the patientFlow triggering is the most commonPressure triggering is another optionFlow TriggeringFlow triggering starts with a base flowThis flow is continuously flowing through the circuitFlow TriggeringFlow triggering starts with a base flowThis flow is continuously flowing through the circuitThe ventilator knows how much flow is going through the circuitThe liter flow leaving the ventilator should be the same as the liter flow coming backFlow TriggeringAs the patient inhales some of the flow goes into the patient lungsThis means less flow is returning to the ventilatorThe ventilator senses that as a patient effort and starts a breathFlow TriggeringThe difference in the flow coming out of the ventilator and coming back to the ventilator is how sensitivity is determinedThe less flow needed to be deflected by the patient the more sensitive it isThe more flow needed to be deflected by the patient the more difficult it is to trigger, i.e. less sensitiveFlow Triggering10 lpm is leaving the ventilator 10 lpm is returning to the ventilatorAs a patient inhales and takes in 2 lpm 8 lpm is returning to the ventilatorThis reduction in returned flow tells the ventilator to start a breath

Flow TriggeringIf you increase the amount of flow needed to be inhaled by the patient the less sensitive the machine is10 lpm is leaving the ventilator 10 lpm is returning to the ventilatorAs a patient inhales and takes in 4 lpm 6 lpm is returning to the ventilatorPressure TriggeringNegative pressure is generated when a patient inhalesPressure TriggeringNegative pressure is generated when a patient inhalesThis negative pressure is in both the patients lungs and the ventilator circuitPressure TriggeringNegative pressure is generated when a patient inhalesThis negative pressure is in both the patients lungs and the ventilator circuitThe ventilator senses the negative pressure as a patient effort and starts a breathPressure TriggeringSo the patient needs to generate -2cmH2O to start a breathIf you increase the amount of negative pressure needed the more difficult it is for the patient to trigger, i.e. less sensitive LimitingLimiting is what contols are in effect during the inspiratory phaseLimitingLimiting is what contols are in effect during the inspiratory phaseAfter a breath is initiated certain limits will be in effect depending on which type of breath is being deliveredLimitingLimiting is what contols are in effect during the inspiratory phaseAfter a breath is initiated certain limits will be in effect depending on which type of breath is being deliveredLimiting factors are what define a type of breathLimitingLimiting is what contols are in effect during the inspiratory phaseAfter a breath is initiated certain limits will be in effect depending on which type of breath is being deliveredLimiting factors are what define a type of breathThe two most common limits areLimitingLimiting is what contols are in effect during the inspiratory phaseAfter a breath is initiated certain limits will be in effect depending on which type of breath is being deliveredLimiting factors are what define a type of breathThe two most common limits arePressureLimitingLimiting is what contols are in effect during the inspiratory phaseAfter a breath is initiated certain limits will be in effect depending on which type of breath is being deliveredLimiting factors are what define a type of breathThe two most common limits arePressureFlowPressure LimitedPressure limited breaths have a set peak airway pressurePressure LimitedPressure limited breaths have a set peak airway pressureThe pressure in the patients lungs will not go over the set pressurePressure LimitedPressure limited breaths have a set peak airway pressureThe pressure in the patients lungs will not go over the set pressureThe following breaths are pressure limitedPressure LimitedPressure limited breaths have a set peak airway pressureThe pressure in the patients lungs will not go over the set pressureThe following breaths are pressure limitedPCVPSVPRVCPressure LimitedPressure Control Ventilation (PCV)Pressure is set with the intention of reaching the peak pressure and holding the pressure for part of the inspiratory timePressure LimitedPressure Control Ventilation (PCV)Pressure is set with the intention of reaching the peak pressure and holding the pressure for part of the inspiratory timePressure Support Ventilation (PSV)Pressure is set to augment a patients own tidal volumePressure LimitedPressure Control Ventilation (PCV)Pressure is set with the intention of reaching the peak pressure and holding the pressure for part of the inspiratory timePressure Support Ventilation (PSV)Pressure is set to augment a patients own tidal volumePressure Regulated Volume Control (PRVC)Pressure changes with each breath with the intention of reaching a specific volumeFlow LimitedFlow limiting is used when a specific volume needs to be deliveredFlow LimitedFlow limiting is used when a specific volume needs to be deliveredEach breath has a rigid flow rate and pattern that will deliver the specific volumeFlow LimitedFlow limiting is used when a specific volume needs to be deliveredEach breath has a rigid flow rate and pattern that will deliver the specific volumeTherefore the breath is limited to a predetermined flowVolume Control is a type of flow limited breathPressure vs. Flow LimitingPressure limited breaths have a variable flow which allows better gas distributionPressure vs. Flow LimitingPressure limited breaths have a variable flow which allows better gas distributionThe pressure is limited therefore if lung conditions change the volume will changePressure vs. Flow LimitingPressure limited breaths have a variable flow which allows better gas distributionThe pressure is limited therefore if lung conditions change the volume will changeIf lungs become stiffer the volume will go down as the pressure remains the samePressure vs. Flow LimitingFlow limiting will deliver a volume no matter what the lung conditions

Pressure vs. Flow LimitingFlow limiting will deliver a volume no matter what the lung conditionsVolume will be consistent but pressures will change

Pressure vs. Flow LimitingFlow limiting will deliver a volume no matter what the lung conditionsVolume will be consistent but pressures will changeIf the lungs become stiffer the pressures will go up

Pressure vs. Flow LimitingPRVC uses pressure limiting but will automatically adjust the pressure to deliver a volumePressure vs. Flow LimitingPRVC uses pressure limiting but will automatically adjust the pressure to deliver a volumeSo the pressure is not set, the volume is setPressure vs. Flow LimitingPRVC uses pressure limiting but will automatically adjust the pressure to deliver a volumeSo the pressure is not set, the volume is setThe ventilator will adjust the pressure to achieve the volumePressure vs. Flow LimitingPRVC uses pressure limiting but will automatically adjust the pressure to deliver a volumeSo the pressure is not set, the volume is setThe ventilator will adjust the pressure to achieve the volumeThis allows for the variable flow which is better for gas distributionPressure vs. Flow LimitingPRVC uses pressure limiting but will automatically adjust the pressure to deliver a volumeSo the pressure is not set, the volume is setThe ventilator will adjust the pressure to achieve the volumeThis allows for the variable flow which is better for gas distributionIf the lungs become stiffer the pressures will go upCyclingCycling is what determines how the breath will stop and allow the patient to exhale

CyclingCycling is what determines how the breath will stop and allow the patient to exhaleMost breaths are time cycled

CyclingCycling is what determines how the breath will stop and allow the patient to exhaleMost breaths are time cycledAny breath type that requires a set Ti is time cycledThese include the following breath types

CyclingCycling is what determines how the breath will stop and allow the patient to exhaleMost breaths are time cycledAny breath type that requires a set Ti is time cycledThese include the following breath typesPRVC

CyclingCycling is what determines how the breath will stop and allow the patient to exhaleMost breaths are time cycledAny breath type that requires a set Ti is time cycledThese include the following breath typesPRVCPCV

CyclingCycling is what determines how the breath will stop and allow the patient to exhaleMost breaths are time cycledAny breath type that requires a set Ti is time cycledThese include the following breath typesPRVCPCVVolume Control

CyclingFlow is also used to cycle a breath off

CyclingFlow is also used to cycle a breath offPressure Support Ventilation (PSV) is flow cycled

CyclingFlow is also used to cycle a breath offPressure Support Ventilation (PSV) is flow cycledAs 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

CyclingFlow is also used to cycle a breath offPressure Support Ventilation (PSV) is flow cycledAs the inspiratory flow starts to slow down the ventilator will sense that the lungs are getting full and cycle off allowing the patient to exhaleDuring that same breath it is being pressure limited

CyclingFlow is also used to cycle a breath offPressure Support Ventilation (PSV) is flow cycledAs the inspiratory flow starts to slow down the ventilator will sense that the lungs are getting full and cycle off allowing the patient to exhaleDuring that same breath it is being pressure limitedSo 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

BaselineBaseline is what limits are in effect during exhalationExhalation is passiveThe only limit will be added pressure, i.e. PEEPThe baseline should be assessed via total PEEP to accurately measure the baselineRise Time or SlopeRise time is part of the inspiration so could be considered a limiting factorRise Time or SlopeRise time is part of the inspiration so could be considered a limiting factorIt is usually not included in the definition of a breathRise Time or SlopeRise time is part of the inspiration so could be considered a limiting factorIt is usually not included in the definition of a breathRise time adjusts the initial flow rate of a breath Rise Time or SlopeRise time is part of the inspiration so could be considered a limiting factorIt is usually not included in the definition of a breathRise 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/SlopeThe less time the Rise time is the faster the breath ramps up to full speedRise Time/SlopeThe less time the Rise time is the faster the breath ramps up to full speedThe longer the Rise Time is the slower the breath reaches peak flowRise Time/SlopeSo 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/SlopeSo 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 breathIf 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 flowRise Time/SlopeA short Rise Time may be helpful in patient with high inspiratory demands, such as asthma

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

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

Inspiratory Cycle OffInspiratory cycle off is part of the flow cycling breathInspiratory Cycle OffInspiratory cycle off is part of the flow cycling breathPressure Support Ventilation (PSV)Inspiratory Cycle OffInspiratory cycle off is part of the flow cycling breathPressure Support Ventilation (PSV)Flow cycling is used to end a PSV breathInspiratory Cycle OffInspiratory cycle off is part of the flow cycling breathPressure Support Ventilation (PSV)Flow cycling is used to end a PSV breathNormal inspiration goes to zero flow and then reverses the flow to exhaleInspiratory Cycle OffInspiratory cycle off is part of the flow cycling breathPressure Support Ventilation (PSV)Flow cycling is used to end a PSV breathNormal inspiration goes to zero flow and then reverses the flow to exhaleBecause 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 exhalingInspiratory Cycle OffInspiratory cycle off is part of the flow cycling breathPressure Support Ventilation (PSV)Flow cycling is used to end a PSV breathNormal inspiration goes to zero flow and then reverses the flow to exhaleBecause 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 exhalingFlow cycling allow the breath to end prior to reaching zero flowInspiratory Cycle OffSome ventilators have a preset flow rate that will cycle the PSV breath into exhalationInspiratory Cycle OffSome ventilators have a preset flow rate that will cycle the PSV breath into exhalationSome ventilators allow the flow rate to be adjustedInspiratory Cycle OffSome ventilators have a preset flow rate that will cycle the PSV breath into exhalationSome ventilators allow the flow rate to be adjustedWhen setting Inspiratory Cycle Off it is a percentageInspiratory Cycle OffSome ventilators have a preset flow rate that will cycle the PSV breath into exhalationSome ventilators allow the flow rate to be adjustedWhen setting Inspiratory Cycle Off it is a percentageThe percentage is based on the peak inspiratory flow achieved during the breathInspiratory Cycle OffSome ventilators have a preset flow rate that will cycle the PSV breath into exhalationSome ventilators allow the flow rate to be adjustedWhen setting Inspiratory Cycle Off it is a percentageThe percentage is based on the peak inspiratory flow achieved during the breathThe percent is what determines when the breath will release the pressure and allow exhalationInspiratory Cycle OffIf you set the Inspiratory Cycle Off at 25% the inspiratory breath will end when the flow is 25% of the peak flow during that breathInspiratory Cycle OffIf you set the Inspiratory Cycle Off at 25% the inspiratory breath will end when the flow is 25% of the peak flow during that breathIf the peak flow was 60 lpm the breath will end at 25% of that or 15 lpmInspiratory Cycle OffIf you set the Inspiratory Cycle Off at 25% the inspiratory breath will end when the flow is 25% of the peak flow during that breathIf the peak flow was 60 lpm the breath will end at 25% of that or 15 lpmThe higher the % set the sooner the breath will be cycled offInspiratory Cycle OffIf you set the Inspiratory Cycle Off at 25% the inspiratory breath will end when the flow is 25% of the peak flow during that breathIf the peak flow was 60 lpm the breath will end at 25% of that or 15 lpmThe higher the % set the sooner the breath will be cycled offThis may cut off a patient breath early