Basics of Mechanical Ventilation for the COVID-19 Patient€¦ · Basics of Mechanical Ventilation...

HoomanPoor,M.D.AssistantProfessorofMedicine

DirectorofPulmonaryVascularDisease,MountSinai-NationalJewishHealthRespiratoryInstituteDivisionofPulmonary,CriticalCareandSleepMedicineZenaandMichaelA.WienerCardiovascularInstitute

IcahnSchoolofMedicineatMountSinai

BasicsofMechanicalVentilationfortheCOVID-19Patient

Financial Disclosures

None

Talk Objectives

• discusstherationaleofpositivepressureventilationforpatientswithARDSsecondarytoCOVID-19

•  reviewthebasicsofvolume-controlledventilation

•  explainhowtosetandadjusttheimportantparametersinvolume-controlledventilationforCOVID-19patientswithARDS

COVID-19 Causes ARDS

ARDSDefinition:•  acute•  bilateralopacities•  PaO2/FIO2ratio<300mmHgwithPEEP≥5cmH2O

•  notcompletelyexplainedbycardiacfailureorvolumeoverload

ARDS Pathophysiology •  lunginjuryandinflammationcreateleakycapillariesandleakyalveoli

•  alveolifillupwithfluid•  gasexchangeimpaired•  alveolicollapse•  lungsbecomestiffer• patientsultimatelydeveloprespiratoryfailure

Thompson,NEJM2017

Ventilator Support in ARDS

• deliverhighamountsofoxygen-  highFIO2

• providepositivepressuretoreduceworkofbreathing

-  ventilatorPUSHESairinsomusclesofinspirationdonothavetoworkashardtoSUCKairin

• providepositiveend-expiratorypressure(PEEP)

-  preventsopenalveolifromcollapsing

How to Inflate Lungs

êPpl

éPalv

Palv=alveolarpressurePpl=pleuralpressure

a)  increasepressureinsideofthelungs(Palv)

b)  decreasethepressureoutsideofthelungs(Ppl)

Poor,BasicsofMechanicalVentilation,2018

spontaneousventilation

Poor,BasicsofMechanicalVentilation,2018

spontaneousventilation

positivepressureventilation

Poor,BasicsofMechanicalVentilation,2018

Poor,BasicsofMechanicalVentilation,2018

Poor,BasicsofMechanicalVentilation,2018

Pair=proximalairwaypressurePalv=alveolarpressureQ=flowR=resistance

𝑄= 𝑃↓𝑎𝑖𝑟  − 𝑃↓𝑎𝑙𝑣 /𝑅 

Poor,BasicsofMechanicalVentilation,2018

Pair=proximalairwaypressurePalv=alveolarpressureQ=flowR=resistance

𝑄= 𝑃↓𝑎𝑖𝑟  − 𝑃↓𝑎𝑙𝑣 /𝑅 

spontaneousventilation

Suckairintolungs

Poor,BasicsofMechanicalVentilation,2018

Pair=proximalairwaypressurePalv=alveolarpressureQ=flowR=resistance

𝑄= 𝑃↓𝑎𝑖𝑟  − 𝑃↓𝑎𝑙𝑣 /𝑅 

positivepressureventilation

Pushairintolungs

Regardless of the mode of ventilation...

•  theventilatorincreasesairwaypressureforasettime

-  airflowintothepatient-  culminatesindeliveredtidalvolume

•  “phasevariables”determinethemodeofventilation-  ventilatorinstructions-  determine“when”and“how”breathsdelivered

𝑄= 𝑃↓𝑎𝑖𝑟  − 𝑃↓𝑎𝑙𝑣 /𝑅 

Phase Variables: “Anatomy of a Breath”

•  triggeràwheninspirationbegins•  targetàhowflowisdeliveredduringinspiration•  cycleàwheninspirationends• baselineàproximalairwaypressureduringexpiration

Poor,BasicsofMechanicalVentilation,2018

Modes of Ventilation

trigger

target

cycle

Forthesakeofsimplicity,use

volume-controlledventilation(VCV)

WhatmodeofventilationshouldIuse?

Trigger

• Whoinitiatesthebreath?-  ventilator-  patient

•  ventilator-triggered-  akaCONTROL-  variablethatissetàtime-  setrespiratoryrate(frequency=1/time)-  RR12bpmisonebreathevery5seconds

• patient-triggered-  akaASSIST-  floworpressurechangessensedbyventilator

Assist-Control à Hybrid Trigger

•  assisttrigger+controltrigger=assist-control(A/C)

“A/C”refersonlytothetrigger.

Volume-controlledventilationusesA/Casthetriggermechanism.

How Much Assist? How Much Control?

controlrespiratoryrate neuralrespiratoryrate-10bpm-breathevery6sec

-20bpm-breathevery3sec

Whatpercentageofthebreathswillbeassist,whatpercentagewillbecontrol?

100%ASSISTControlrateclockresetsafteran“assist”breath.

How Much Assist? How Much Control?

controlrespiratoryrate neuralrespiratoryrate-10bpm -20bpm

-breathevery3sec

How Much Assist? How Much Control?

controlrespiratoryrate neuralrespiratoryrate-30bpm-breathevery2sec

-20bpm-breathevery3sec

Whatpercentageofthebreathswillbeassist,whatpercentagewillbecontrol?

100%CONTROL

controlrespiratoryrate

lastbreathwasa“control”breath

actualrespiratoryrate

Target

Howisflowduringinspirationdetermined?-  flowrateissetinvolume-controlledventilation

Poor,BasicsofMechanicalVentilation,2018

deceleratingrampshape

peakinspiratoryflowrate

VCV is a Flow-Targeted Mode

VCV is a Flow-Targeted Mode

𝑄= 𝑃↓𝑎𝑖𝑟  − 𝑃↓𝑎𝑙𝑣 /𝑅 

Qwillnotchangewithchangesinrespiratory

system

Pairwillchangewithchangesinrespiratorysystem

pressurewaveform

peakpressure

Target

Poor,BasicsofMechanicalVentilation,2018

𝑄= 𝑃↓𝑎𝑖𝑟  − 𝑃↓𝑎𝑙𝑣 /𝑅 

𝑄= 𝑃↓𝑎𝑖𝑟  − 𝑃↓𝑎𝑙𝑣 /𝑅 

𝑄= 𝑃↓𝑎𝑖𝑟  − 𝑃↓𝑎𝑙𝑣 /𝑅 

bitingendotrachealtube

flowunchanged flow-targetedmode

Target

Poor,BasicsofMechanicalVentilation,2018

𝑄= 𝑃↓𝑎𝑖𝑟  − 𝑃↓𝑎𝑙𝑣 /𝑅 

𝑄= 𝑃↓𝑎𝑖𝑟  − 𝑃↓𝑎𝑙𝑣 /𝑅 

𝑄= 𝑃↓𝑎𝑖𝑟  − 𝑃↓𝑎𝑙𝑣 /𝑅 

sustainedinspiratoryeffort

flowunchanged flow-targetedmode

Cycle

Whendoesinspirationend?-  volumeissetinvolume-controlledventilation

Poor,BasicsofMechanicalVentilation,2018

tidalvolume

exhaledtidalvolumereturningtoventilator

Low Tidal Volume Ventilation

• hightidalvolumeinARDScauseslungstretchandfurtherlungdamage

-  “volutrauma”

•  lowtidalvolumeventilationisessential-  settidalvolumeto6cc/kgofidealbodyweight-  canbeuncomfortableforpatients(willlikelyneedsedation,andsometimesevenparalysis)

Baseline

• Whatisproximalairwaypressureduringexpiration?

•  akaPEEP

Poor,BasicsofMechanicalVentilation,2018

PEEP in ARDS

•  repetitiveopeningandclosingofalveolicausesfurtherlungdamage

-  “atelectrauma”

• PEEPpreventsopenalveolifromclosing

• maintainingalveoliopenwillimprovegasexchange

INCLUSION CRITERIA: Acute onset of 1. PaO2/FiO2 ≤ 300 (corrected for altitude) 2. Bilateral (patchy, diffuse, or homogeneous) infiltrates consistent with

pulmonary edema 3. No clinical evidence of left atrial hypertension PART I: VENTILATOR SETUP AND ADJUSTMENT 1. Calculate predicted body weight (PBW)

Males = 50 + 2.3 [height (inches) - 60] Females = 45.5 + 2.3 [height (inches) -60]

2. Select any ventilator mode 3. Set ventilator settings to achieve initial VT = 8 ml/kg PBW 4. Reduce VT by 1 ml/kg at intervals ≤ 2 hours until VT = 6ml/kg PBW. 5. Set initial rate to approximate baseline minute ventilation (not > 35

bpm). 6. Adjust VT and RR to achieve pH and plateau pressure goals below.

AARRDDSSnnee tt OXYGENATION GOAL: PaO2 55-80 mmHg or SpO2 88-95% Use a minimum PEEP of 5 cm H2O. Consider use of incremental FiO2/PEEP combinations such as shown below (not required) to achieve goal. Lower PEEP/higher FiO2

FiO2 0.3 0.4 0.4 0.5 0.5 0.6 0.7 0.7 PEEP 5 5 8 8 10 10 10 12

NIH NHLBI ARDS Clinical Network FiO2 0.7 0.8 0.9 0.9 0.9 1.0 PEEP 14 14 14 16 18 18-24 Mechanical Ventilation Protocol Summary Higher PEEP/lower FiO2 FiO2 0.3 0.3 0.3 0.3 0.3 0.4 0.4 0.5 PEEP 5 8 10 12 14 14 16 16 FiO2 0.5 0.5-0.8 0.8 0.9 1.0 1.0 PEEP 18 20 22 22 22 24 __________________________________________________________ PLATEAU PRESSURE GOAL: ≤ 30 cm H2O Check Pplat (0.5 second inspiratory pause), at least q 4h and after each change in PEEP or VT. If Pplat > 30 cm H2O: decrease VT by 1ml/kg steps (minimum = 4 ml/kg). If Pplat < 25 cm H2O and VT< 6 ml/kg, increase VT by 1 ml/kg until Pplat > 25 cm H2O or VT = 6 ml/kg. If Pplat < 30 and breath stacking or dys-synchrony occurs: may increase VT in 1ml/kg increments to 7 or 8 ml/kg if Pplat remains < 30 cm H2O.

INCLUSION CRITERIA: Acute onset of 1. PaO2/FiO2 ≤ 300 (corrected for altitude) 2. Bilateral (patchy, diffuse, or homogeneous) infiltrates consistent with

pulmonary edema 3. No clinical evidence of left atrial hypertension PART I: VENTILATOR SETUP AND ADJUSTMENT 1. Calculate predicted body weight (PBW)

Males = 50 + 2.3 [height (inches) - 60] Females = 45.5 + 2.3 [height (inches) -60]

2. Select any ventilator mode 3. Set ventilator settings to achieve initial VT = 8 ml/kg PBW 4. Reduce VT by 1 ml/kg at intervals ≤ 2 hours until VT = 6ml/kg PBW. 5. Set initial rate to approximate baseline minute ventilation (not > 35

bpm). 6. Adjust VT and RR to achieve pH and plateau pressure goals below.

AARRDDSSnnee tt OXYGENATION GOAL: PaO2 55-80 mmHg or SpO2 88-95% Use a minimum PEEP of 5 cm H2O. Consider use of incremental FiO2/PEEP combinations such as shown below (not required) to achieve goal. Lower PEEP/higher FiO2

FiO2 0.3 0.4 0.4 0.5 0.5 0.6 0.7 0.7 PEEP 5 5 8 8 10 10 10 12

NIH NHLBI ARDS Clinical Network FiO2 0.7 0.8 0.9 0.9 0.9 1.0 PEEP 14 14 14 16 18 18-24 Mechanical Ventilation Protocol Summary Higher PEEP/lower FiO2 FiO2 0.3 0.3 0.3 0.3 0.3 0.4 0.4 0.5 PEEP 5 8 10 12 14 14 16 16 FiO2 0.5 0.5-0.8 0.8 0.9 1.0 1.0 PEEP 18 20 22 22 22 24 __________________________________________________________ PLATEAU PRESSURE GOAL: ≤ 30 cm H2O Check Pplat (0.5 second inspiratory pause), at least q 4h and after each change in PEEP or VT. If Pplat > 30 cm H2O: decrease VT by 1ml/kg steps (minimum = 4 ml/kg). If Pplat < 25 cm H2O and VT< 6 ml/kg, increase VT by 1 ml/kg until Pplat > 25 cm H2O or VT = 6 ml/kg. If Pplat < 30 and breath stacking or dys-synchrony occurs: may increase VT in 1ml/kg increments to 7 or 8 ml/kg if Pplat remains < 30 cm H2O.

Use the High PEEP Ladder

• COVID-19patientsappeartobevery“PEEP-responsive”

• donotincreasePEEPabove16cmH2Owithoutguidancefromacriticalcarephysician

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PEEP

FIO2

Plateau Pressure (Ppl) •  estimateofthemaximumpressureinthealveolusduringtherespiratorycycle

•  tomeasurePpl,performinspiratorypausemaneuver

-  aftertidalvolumeisdelivered,expiratoryvalveremainsshutandairdoesnotleavepatient

-  pressuremeasuredatendofmaneuveriscalled“plateaupressure”

•  highPplcanleadto“barotrauma”-  pneumothorax,pneumomediastinum-  goalPplinARDSis≤30cmH2O

Plateau Pressure

plateaupressure

Your COVID-19 Patient Just Got Intubated

•  placeonvolume-controlledventilation•  setrespiratoryrateto20bpm•  settidalvolumeto6cc/kgofidealbodyweight•  setFIO2to100%•  setPEEPto15cmH20•  checkplateaupressure(Ppl)

-  ifPpl>30cmH2O,reducetidalvolumeto5cc/kg-  ifPplstill>30cmH2O,callforhelp

•  ensurepatientiswellsedated•  checkABGorVBG30minutesaftersettingsadjustedtoensureappropriatepH

-  ifpH<7.2,increaseRR(maximumof35bpm)

Your COVID-19 Patient is Improving

• weanFIO2andPEEPaspertheARDSnetladdertoensureSpO288-95%

• waitatleast12hoursbetweenchangesinPEEP

INCLUSION CRITERIA: Acute onset of 1. PaO2/FiO2 ≤ 300 (corrected for altitude) 2. Bilateral (patchy, diffuse, or homogeneous) infiltrates consistent with

pulmonary edema 3. No clinical evidence of left atrial hypertension PART I: VENTILATOR SETUP AND ADJUSTMENT 1. Calculate predicted body weight (PBW)

Males = 50 + 2.3 [height (inches) - 60] Females = 45.5 + 2.3 [height (inches) -60]

2. Select any ventilator mode 3. Set ventilator settings to achieve initial VT = 8 ml/kg PBW 4. Reduce VT by 1 ml/kg at intervals ≤ 2 hours until VT = 6ml/kg PBW. 5. Set initial rate to approximate baseline minute ventilation (not > 35

bpm). 6. Adjust VT and RR to achieve pH and plateau pressure goals below.

AARRDDSSnnee tt OXYGENATION GOAL: PaO2 55-80 mmHg or SpO2 88-95% Use a minimum PEEP of 5 cm H2O. Consider use of incremental FiO2/PEEP combinations such as shown below (not required) to achieve goal. Lower PEEP/higher FiO2

FiO2 0.3 0.4 0.4 0.5 0.5 0.6 0.7 0.7 PEEP 5 5 8 8 10 10 10 12

NIH NHLBI ARDS Clinical Network FiO2 0.7 0.8 0.9 0.9 0.9 1.0 PEEP 14 14 14 16 18 18-24 Mechanical Ventilation Protocol Summary Higher PEEP/lower FiO2 FiO2 0.3 0.3 0.3 0.3 0.3 0.4 0.4 0.5 PEEP 5 8 10 12 14 14 16 16 FiO2 0.5 0.5-0.8 0.8 0.9 1.0 1.0 PEEP 18 20 22 22 22 24 __________________________________________________________ PLATEAU PRESSURE GOAL: ≤ 30 cm H2O Check Pplat (0.5 second inspiratory pause), at least q 4h and after each change in PEEP or VT. If Pplat > 30 cm H2O: decrease VT by 1ml/kg steps (minimum = 4 ml/kg). If Pplat < 25 cm H2O and VT< 6 ml/kg, increase VT by 1 ml/kg until Pplat > 25 cm H2O or VT = 6 ml/kg. If Pplat < 30 and breath stacking or dys-synchrony occurs: may increase VT in 1ml/kg increments to 7 or 8 ml/kg if Pplat remains < 30 cm H2O.

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Further Reading

AvailablefreeonlineviatheLevyLibrarywebsite

Good Luck!