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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
16
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.
16
Further Reading
AvailablefreeonlineviatheLevyLibrarywebsite
Good Luck!