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Managing ARDS 2010

John J. Marini

University of Minnesota

SCCMMiami Beach 2010

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So, Whats New This Year?

Conceptual Advances VILI causes

Individual Complexity

Monitoring Use of Pes for PTP Availability of FRC

Treatment Options Extra-Pulmonary Gas Exchange

Clinical Trials Evidence / Meta-Analysis PEEP

Proning

Principal Theme:Principal Theme:

Individually Titrate Rx

Severity Timing

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Take-Away Messages-1

ARDS is a set of problems, not a disease.

For many treatments, timing is veryimportant.

VILI vulnerability is greatest in earliestphase.

Both tidal volume and PEEP must be

adjusted empiricallybased on ventilationdemand, lung capacity, and breathingeffort.

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Take-Away Messages-2

Reducing demandis essential.

Open Lungs are not foreverybody. Proning helps severe recruiters, not

everyone.

Maintaining net fluid balance is crucial tooutcome.

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The Myth of ARDS

Diverse Etiologies

Common Pathophysiology

Unified Clinical Approach

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ARDS Diversity and

Responsiveness to Rx

Underlying etiology

Identification accuracy

Pathophysiologic expression (Genetics) Severity

Regional mechanics

Phase of illness

Background co-morbidities and co-interventions

Need to Individualize

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PEEP Tidal Volume

V I L I

Plateau

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Stretch

Shear

Recognized Mechanisms of

Airspace Injury

Opening & Closure

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Stretch

Shear

Airway Trauma

Recognized Mechanisms of

Airspace Injury

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PEEP Tidal Volume

Stress Strain

Strain (VT+FRC) / FRC

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PEEP

Alveolar Pressure

Less Driving PressureShorter Lever Arm

Fewer Units

at Risk

Open Lung Rationale

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Primary Goal for PEEP Selection

Minimize the airway pressures

needed to accomplish

simultaneouslythe goals of lung

protection, gas exchange, and

oxygen delivery.

High PEEP ??

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9Phoenix, Susan; Anesthesiology. 110(5):1098-1105, May 2009Phoenix Anesthesiology May 2009

ARDS Rel Risk ofBarotraumaHigh vs. Low PEEP

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0

10

20

30

40

50

60

1st Q 2nd Q 3rd Q 4th Q

LOV

Control

Baseline Oxygenation Index (FiO2 x MAP / PaO2)

Sub-Groups of the Negative LOVS Trial

P=0.57PEEP Refractory?

Not Sick Enough

Severity

Recruitability

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6

Fig. 2

Phoenix Anesthesiology May 2009

ARDS Relative Risk ofDeathHigh vs. Low PEEP

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Setting Plateau Pressure and PEEP...What

Surrounds the Lung is Important!

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Lung Stress is Proportional to

TransalveolarPressureWhich Plateau Pressure Is Safest?

Depends on Effort and Chest Wall Stiffness!

Stiff CW Active Inspiration

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Good Idea, but

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Esophageal Balloon Estimation of PPL

Not Always Simple, Accurate, or

Representative

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6ml/kg--Could One Size Fit All?

Chest Wall

Innate Capacity

Whats His

VentilatoryDemand?

PBW = 85 Kg

PBW = 50 Kg

PBW = 130 Kg

What About Tidal Volume?

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Adjust Tidal Volume for Demand

Weight

(pbw) Kg

Minute

Ventilation

6ml/kg Frequency

50 10

15

20

300 ml

500--30

670--30

33

50

67

85 10

15

20

510 ml

500--30

670--30

19

28

38

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VTPBW is NotGood Enough

(VT+FRC ) / FRC

GattinoniAJRCCM2008

Sick LUNGS Are NotUniform

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Absolute Aerated Lung Volume

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Best PEEPin 2010? ... Set Lowest

Feasible VT & Titrate Decrementally!

Chest Wall

Innate Capacity

Adjust VT forPredictedWeightTitratePressures to

Physiologic Endpoints

and Adjust VT for

Minute Ventilation!

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Recruitment is Transientif

PEEP Unchanged Afterward

RimensbergerICM2000

VOLUME

(% TLC)

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10

20

30

40

50

10-15 Minutes

AirwayPress

ure(cmH2O)

Decremental PEEP Setting

After Recruitment

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Check Inspiratory PV Shape With Constant

Flow After Setting VT & PEEP

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Inspiratory PV Shape Can Be

Characterized By Stress Index

Grasso, Ranieri

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Tidal Recruiting

Predominates?

Over Distention

Predominates?OK?

Stress index is notwell suited

for heterogeneous lungs orabnormal chest walls.

CONSTANT

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Time (seconds)

00 3030 6060 9090

--0.100.10

--0.080.08

--0.060.06

--0.040.04

--0.020.02

0.000.00

0.020.02

0.040.04

0.060.06

0.080.08

IMPEDANCE

CHANGES

UPPER LUNG

TOTAL LUNG

LOWER LUNG

CONSTANT

FLOW

Amato

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APRV and HFV

Both are open lung approaches [ mPaw]

APRV

Emphasizes spontaneous breathing

One mode for all phases HFV

Requires deep sedation

Best used early

In experienced hands, both are attractive options Neitherhas proven benefit vs. optimized lung

protective (open lung?) ventilation

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VT , Plateau Pressure, and PEEP

Is ThatAllWe Need to Know??

I

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ConditionallyImportant to VILI During

High Stress / Strain Ventilation

PaCO2 and pH

Minute Ventilation and

Flow Frequency

Position

Vascular Pressures

Temperature Other

dP/dt (Inspiratory Flow)

I:E (Adverse Tension-Time

Product)

Off-Radar Stealth Factors??

C diti l B fit f H i

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ConditionalBenefit of Hypercapnia

Stress Severity

Kregenow, Crit Care Med2006

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A Fluid Conservative Strategy

Reduces Time On Ventilator

NEJM June 2006

Lung-Protective Ventilation

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Have We IgnoredAirwayFlow?

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FlowDamage to the BabyLung?

>3 times effective Stretch

>3 times theAir Flow

ForAnyGiven Minute

Ventilation

??????

70 L/minSpecific Flow >3 x 70 = 210 L/min!!

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How Might We Modify SpecificFlow

Through The Baby Lung?

Decrease the Driving Pressure (PCV)

Alter the Flow Profile (ACV)

Adjust the Flow Amplitude (I:E Ratio)

Reduce the Minute Ventilation Need

Sedation / Paralysis

Fever reduction

Extrapulmonary CO2Elimination

Nova Lung, TGI

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Importance ofFlow to VILI

Two Components

Minute Ventilation

Cumulative Volume Over Time

DeterminesAverage Inspiratory Flow -- VE/Ti

Inspiratory Flow Characteristics

Settings

Flow (ACV) Driving Pressure and I:E ratio (PCV)

Waveform

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Lower Frequency & VE Reduce

VILI

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Rich, J Trauma, 2000

Inflation PatternsAirway Pressure vs. Time

Extended Time at Pmax Reduced dP/dT

Lower Breathing Frequency

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Low Pressure

Control

High Pressure

Normal Rate

High PressureExtended I:E

High Pressure

Short I:E Ratio

High Pressure

Low Insp. Flow

Rich, J. Trauma, 2000

Stretch?

Shear? Mean PAW?

Low f

Normal f

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Arterio-Venous Gradient Drives Flow

(Passive)

Nova-Lung

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Pump-Powered Veno-Venous Flow

Hemo-lung

Pump Regulated Blood Flow

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Two BirdsOne Stone

Terragni Crit Care Med2009

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Therapeutic Hypothermia For ARDS?

O2 Demand

Inflammation

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RegionalHighPEEP-like Effect

Sustained Traction of Supine Dependent Units

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DPaCO2 (115 pz)

DPaCO2

0 7 14 21 28

30

40

50

60

70

80

90

100

Days

Survival%

Recruiters (?) Benefited From Proning

p=0.01

Gattinoni Crit Care Med2003

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Proning May Benefit the Most

Seriously Ill ARDS Subset

M

ortalityR

ate

> 49 40- 49 31- 40 0 - 310.0

0.1

0.2

0.3

0.4

0.5 Supine

*p

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Copyright restrictions may apply.

Kaplan-Meier Survival Curves of the Prone-Supine II Study Population: Entire Population andPatients With Moderate and Severe Hypoxemia

Taccone et al, JAMA 2009

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Proning Improves O2 Exchange

in AllPatient Categories

Su

detal.,IntCare

Med

2010

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Proning May Improve Mortality in

Severely IllPatients with ARDS

Sude

tal.,IntCareM

ed

2010

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Proning Favors Lymphatic Drainage

And Helps Drain Airway Secretions

ProneProne

SupineSupine

Albert & Hubmayr, AJRCCM2000

ProneProne

SupineSupine

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Proning May Reduce VAP

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The Environment Changes

ImpressivelyOver Time

Recruitability, VILI risk, &

Advisability of Therapies

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PneumoniaDay 1

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Primary ARDS

Day 2 Day 7

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Before Proning

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Propagation After Proning

N S t i l Di

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PEEP

Alveolar Pressure

Shorter Lever Arm

Fewer Units at Risk

PEEP

Non-Symmetrical Disease

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PEEP

Alveolar Pressure

Shorter Lever Arm

Dependent Position

Low PEEP

High Driving Pressure

Hospital-Acquired ARDS?

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Take-Away Messages

ARDS is a set of problems, not a disease.

For many treatments, timing is very important.

VILI vulnerability is greatest in earliest phase.

Both tidal volume and PEEP must be adjustedempiricallybased on demand and lung capacity.

Reducing demandis essential.

Proning is helpful for some, not all.

Maintaining net fluid balance is crucial tooutcome.

High PEEP and Open Lungs are for early &sickest

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End of this LongStory?

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Thank You

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I t f St id I i N t ?

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Impact of SteroidsImpressive or Not ?

Conditional on Timing