Vent ModesVent ModesEducation and ExplanationEducation and Explanation

**Rule #1: Do not touch the vent.****Rule #1: Do not touch the vent.**Kindly ask your Respiratory Therapist to Kindly ask your Respiratory Therapist to

make the change for you.make the change for you.

IMVIMV

IMV stands for IMV stands for Intermittent Mandatory Intermittent Mandatory VentilationVentilation– This mode of ventilation would deliver a breath This mode of ventilation would deliver a breath

based entirely on time.based entirely on time.» If you set a rate of 12 a breath would be given every If you set a rate of 12 a breath would be given every

5 seconds regardless of where the patient is in their 5 seconds regardless of where the patient is in their breathing cyclebreathing cycle

– This is a mode of ventilation that is no longer This is a mode of ventilation that is no longer used because it can cause over stretching and used because it can cause over stretching and barotrauma.barotrauma.

IMV (continued)IMV (continued) What can be set?What can be set?

– Rate – How often the patient receives a breathRate – How often the patient receives a breath– Inspiratory Time/Flow – How quickly the patient receives Inspiratory Time/Flow – How quickly the patient receives

the ventilator breath. Measured in Sec, or LPMthe ventilator breath. Measured in Sec, or LPM– FiO2 – The FiO2 – The Fractional inspired OxygenFractional inspired Oxygen from 21% - 100% from 21% - 100%– Pressure/Volume – The amount of pressure or the volume Pressure/Volume – The amount of pressure or the volume

to be received.to be received.» Pressure measured in cmH2OPressure measured in cmH2O

– PEEP – PEEP – Positive End Expiratory Pressure Positive End Expiratory Pressure » Is used to distend the alveoli and thin the alveolar capillary (AC) Is used to distend the alveoli and thin the alveolar capillary (AC)

membrane.membrane.» Improves the gas transfer for the oxygen into the capillary system.Improves the gas transfer for the oxygen into the capillary system.» Increases a patients functional residual capacity (FRC)Increases a patients functional residual capacity (FRC)

AC/VCAC/VC

Assist ControlAssist Control or or Volume ControlVolume Control– Same mode of ventilation with a different name.Same mode of ventilation with a different name.– Every breath is the same, and a vent breath.Every breath is the same, and a vent breath.– Takes all the work away from the patient.Takes all the work away from the patient.– May be a “first choice” mode of ventilation in other May be a “first choice” mode of ventilation in other

institutions.institutions.– Can predispose a patient to atelectasis due to no change Can predispose a patient to atelectasis due to no change

in volume.in volume.– If: Patient is set at a rate of 12 and a Tidal Volume (Vt) If: Patient is set at a rate of 12 and a Tidal Volume (Vt)

of 500 but breathing 20 times per minute what is the of 500 but breathing 20 times per minute what is the patients Minute Ventilation (MV)?patients Minute Ventilation (MV)?

AC/VC (continued)AC/VC (continued)

It would be 10 LPM because every triggered It would be 10 LPM because every triggered breath is a volume of 500 mL.breath is a volume of 500 mL.

The set rate is really a “back up” rate.The set rate is really a “back up” rate. If the patient is sedated the rate of 12 will kick in If the patient is sedated the rate of 12 will kick in

and the patient will receive a breath every 5 and the patient will receive a breath every 5 seconds at the desired I time or flow.seconds at the desired I time or flow.

Have to make sure the I time is adequate for their Have to make sure the I time is adequate for their RR. Can easily become inversed if the patient is RR. Can easily become inversed if the patient is tachypneic.tachypneic.

AC/VC (continued)AC/VC (continued)

What can be set?What can be set?– RateRate– Inspiratory Time (I time) or Flow LPMInspiratory Time (I time) or Flow LPM– FiO2FiO2– VolumeVolume– PEEPPEEP

PCPC

Pressure ControlPressure Control– A pressure is set instead of a volume.A pressure is set instead of a volume.

– Every breath is still the same, and a “back up” rate is Every breath is still the same, and a “back up” rate is set.set.

» Same:Same: PressurePressure I time or FlowI time or Flow

– Volume delivered is determined by the patients lung Volume delivered is determined by the patients lung compliance.compliance.

– Have to make sure the I time is adequate for their RR. Have to make sure the I time is adequate for their RR. Can easily become inversed if the patient is tachypneic.Can easily become inversed if the patient is tachypneic.

So, what is lung compliance?So, what is lung compliance?

Lung compliance is how easily a breath can be pushed Lung compliance is how easily a breath can be pushed into the lung.into the lung.– Expressed as mL/cmH2OExpressed as mL/cmH2O– Can be static or dynamicCan be static or dynamic

» Static is preferredStatic is preferred

What can decrease lung complianceWhat can decrease lung compliance– BronchospasmBronchospasm– InflammationInflammation– Pulmonary EdemaPulmonary Edema– MucusMucus– Size of the endotubeSize of the endotube– Auto-PEEPAuto-PEEP– Pleural EffusionPleural Effusion– PneumoniaPneumonia– PneomothoraxPneomothorax– Anything that makes it more difficult to push a breath into a patientAnything that makes it more difficult to push a breath into a patient

SIMVSIMV

SIMV stands for SIMV stands for Synchronized Intermittent Synchronized Intermittent Mandatory VentilationMandatory Ventilation– This mode uses a microprocessor to determine where This mode uses a microprocessor to determine where

the patient is in their breathing cycle and will fit the the patient is in their breathing cycle and will fit the breath at the beginning of inspiration or in-between breath at the beginning of inspiration or in-between spontaneous breathsspontaneous breaths

– Much less likely to “stack breaths” and helps encourage Much less likely to “stack breaths” and helps encourage comfort on the vent.comfort on the vent.

– Patient will breath spontaneous volumes unassisted by Patient will breath spontaneous volumes unassisted by the vent in-between the vent breaths.the vent in-between the vent breaths.

SIMV VCSIMV VC

What can be set?What can be set?– RateRate– VolumeVolume– I time or FlowI time or Flow– FiO2FiO2– PEEPPEEP

SIMV PCSIMV PC

What can be set?What can be set?– RateRate– PressurePressure– I time or FlowI time or Flow– FiO2FiO2– PEEPPEEP

Now lets add PSVNow lets add PSV

PSV or PSV or Pressure Support VentilationPressure Support Ventilation– Is a pressure that augments a patients spontaneous Is a pressure that augments a patients spontaneous

breaths.breaths.– Is set as a pressure greater than the baseline PEEP.Is set as a pressure greater than the baseline PEEP.– Helps the patient overcome the resistance of the Helps the patient overcome the resistance of the

endotracheal tube.endotracheal tube.– Give the patient assistance for the work put in.Give the patient assistance for the work put in.– Volume of PS breath is completely determined by the Volume of PS breath is completely determined by the

patient effort.patient effort.– Most all “modern” modes of ventilation can have PS.Most all “modern” modes of ventilation can have PS.

» Ie: SIMV VC + PSV, SIMV PC +PSV, SIMV PRVC + PSVIe: SIMV VC + PSV, SIMV PC +PSV, SIMV PRVC + PSV

PRVCPRVC

Pressure Regulated Volume ControlPressure Regulated Volume Control– Combines the best of two modes of ventilation.Combines the best of two modes of ventilation.

» Allows the patient to breath in as much flow as they Allows the patient to breath in as much flow as they demand…..BUTdemand…..BUT

Is delivered over a set I time.Is delivered over a set I time. Set to a target volume.Set to a target volume. Pressure delivered will increase or decrease to lung Pressure delivered will increase or decrease to lung

compliancecompliance Is like having a therapist set the patient’s vent in PC and Is like having a therapist set the patient’s vent in PC and

adjusting the pressure each breath to acheave the target adjusting the pressure each breath to acheave the target volume.volume.

Every breath is a PRVC breath.Every breath is a PRVC breath.

PRVC (continued)PRVC (continued)

Not good for a patient who is breathing a lot Not good for a patient who is breathing a lot spontaneously.spontaneously.– The vent has a difficult time reaching the target volume The vent has a difficult time reaching the target volume

when the patient’s lung compliance is changing when the patient’s lung compliance is changing drastically due to spontaneous (negative pressure) drastically due to spontaneous (negative pressure) breaths.breaths.

– Works well when a patient’s overall respiratory rate is Works well when a patient’s overall respiratory rate is 20 or less, and their spontaneous volumes are about that 20 or less, and their spontaneous volumes are about that of the set volumeof the set volume

» Otherwise the patient could be under ventilated compared to Otherwise the patient could be under ventilated compared to set MVset MV

PRVC (continued)PRVC (continued)

At Sparrow hospital it is customary to place At Sparrow hospital it is customary to place patients in SIMV PRVC+PSV.patients in SIMV PRVC+PSV.

This allows the patients spontaneous This allows the patients spontaneous breaths to be pressure supported while breaths to be pressure supported while assuring a specific MV is achieved.assuring a specific MV is achieved.– This mode of ventilation is only offered on the This mode of ventilation is only offered on the

newest generation of vents (Servo I and Servo newest generation of vents (Servo I and Servo S), and is better than PRVC with assuring the S), and is better than PRVC with assuring the set MV.set MV.

Normal Vent SettingsNormal Vent Settings

Since the ARDS Net Study, hospitals Since the ARDS Net Study, hospitals around the country have been setting lower around the country have been setting lower Vt to decrease mortality.Vt to decrease mortality.– Normal:Normal:

» Vt = 8-10 cc per Kg of Ideal Body Weight (IBW)Vt = 8-10 cc per Kg of Ideal Body Weight (IBW)

» RR = 10-14 breaths per minuteRR = 10-14 breaths per minute

» FiO2 = Starts at 100% and weaned to pt toleranceFiO2 = Starts at 100% and weaned to pt tolerance

» I time = Usually set by the RT at 1 secI time = Usually set by the RT at 1 sec Increased or decreased based off of graphics and pt Increased or decreased based off of graphics and pt

comfort / respiratory cycle.comfort / respiratory cycle.

How To Change ABG’s With How To Change ABG’s With The VentThe Vent

To increase PO2To increase PO2– Increase FiO2 till it is 60% then consider Increase FiO2 till it is 60% then consider

increasing the PEEP.increasing the PEEP.– Increase the PEEPIncrease the PEEP

» This will allow for recruitment of alveoliThis will allow for recruitment of alveoli

» This will thin the AC membraneThis will thin the AC membrane

» O2 exchange will become easierO2 exchange will become easier

» Be Aware: Too high of PEEP can cause a decrease Be Aware: Too high of PEEP can cause a decrease in venous return or tamponade the heart (decrease in venous return or tamponade the heart (decrease BP) BP)

Changing ABG’s With The Vent Changing ABG’s With The Vent (continued)(continued)

Decrease PCO2Decrease PCO2– Increase the rateIncrease the rate

» Increasing the rate increases the patients MVIncreasing the rate increases the patients MV» Be Aware: Too high of a rate can cause air trapping Be Aware: Too high of a rate can cause air trapping

especially in those with an obstructive lung disease.especially in those with an obstructive lung disease.» Cuts into E time or the amount of time a patient has to Cuts into E time or the amount of time a patient has to

exhale.exhale.

– Increase the Vt.Increase the Vt.» This increases MV and is only recommended in patients This increases MV and is only recommended in patients

with compliant lungswith compliant lungs» Be Aware: Too high of a Vt will cause barotrauma and Be Aware: Too high of a Vt will cause barotrauma and

cytokine release.cytokine release.

This is the simplest mode of ventilation, This is the simplest mode of ventilation, and it is placed on the sickest patients.and it is placed on the sickest patients.

Works like a speakerWorks like a speaker Is the only vent that works off of an active Is the only vent that works off of an active

ventilation concept.ventilation concept.– All other modes of ventilation we push the All other modes of ventilation we push the

breath in and the patient passively exhales.breath in and the patient passively exhales.– With the oscillator we push the breath in and With the oscillator we push the breath in and

pull the breath out with a piston.pull the breath out with a piston.

HFOV (High Frequency HFOV (High Frequency Oscillation Ventilation)Oscillation Ventilation)

HFOV (continued)HFOV (continued)

Works well as an oxygenator, but not so well Works well as an oxygenator, but not so well as a ventilator.as a ventilator.

Should be considered when a patients FiO2 Should be considered when a patients FiO2 is greater than 60% on a PEEP greater than is greater than 60% on a PEEP greater than 10cm H2O10cm H2O

Only 4 things are set and control ventilation.Only 4 things are set and control ventilation.– MAP (works like PEEP and is started 2-MAP (works like PEEP and is started 2-

4cmH2O greater than that on the ventilator.4cmH2O greater than that on the ventilator.

HFOV (continued)HFOV (continued)

– FiO2 (amount of inspired O2. Normally set at 100% and FiO2 (amount of inspired O2. Normally set at 100% and weaned down)weaned down)

– The P or The P or d d P (this is where ventilation occurs)P (this is where ventilation occurs)» Is initially set by increasing till there is jiggling in the Is initially set by increasing till there is jiggling in the

mid thigh. (YES REALLY)mid thigh. (YES REALLY) This is called the Chest Wiggle Factor (CWF)This is called the Chest Wiggle Factor (CWF)

» Please remember: Only about 20% of the actual pressure Please remember: Only about 20% of the actual pressure set makes it to the alveoli.set makes it to the alveoli.

– And finally the HZ. (1HZ = 60 cycles in a minute)And finally the HZ. (1HZ = 60 cycles in a minute)» Is initially set between 3HZ and 6HZIs initially set between 3HZ and 6HZ» The Vt is determined by the amount of distance between The Vt is determined by the amount of distance between

peaks in the waves.peaks in the waves.

How To Change Your ABG With How To Change Your ABG With HFOVHFOV

To increase PO2To increase PO2– Increase the FiO2Increase the FiO2– Increase the MAPIncrease the MAP

» This will thin the alveolar wall and make it easier to This will thin the alveolar wall and make it easier to move the O2 into the capillary system.move the O2 into the capillary system.

» Be aware: Just like PEEP, the higher the setting the Be aware: Just like PEEP, the higher the setting the more likely for a decrease in venous return or more likely for a decrease in venous return or tamponade of the heart to occur. (decrease BP)tamponade of the heart to occur. (decrease BP)

Changing ABGs with HFOV Changing ABGs with HFOV (continued)(continued)

To decrease PCO2To decrease PCO2– Increase the PIncrease the P

» This increases the venilatory pressure.This increases the venilatory pressure.

– Decrease the rateDecrease the rate» Wait a minute this goes against everything we know!Wait a minute this goes against everything we know!

» The oscillator is trapping gas in the lung, by The oscillator is trapping gas in the lung, by decreasing the HZ we allow more time for CO2 to decreasing the HZ we allow more time for CO2 to escape. (this increases the Vt)escape. (this increases the Vt)

– As a last ditch the cuff can be deflated some to As a last ditch the cuff can be deflated some to allow a leak and more CO2 to escape.allow a leak and more CO2 to escape.

Good LuckGood Luck

Remember every patient is differentRemember every patient is different– Just because a mode of ventilation works with Just because a mode of ventilation works with

most patients does not always make it a fit for most patients does not always make it a fit for all your patients.all your patients.

And lastlyAnd lastly– If you have a question, please ask your If you have a question, please ask your

Respiratory Therapist.Respiratory Therapist.

Thank YouThank You