PEEP Cheifetz (Egypt) 3-09 (Final Version)

8/14/2019 PEEP Cheifetz (Egypt) 3-09 (Final Version)

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Ira M Cheifetz MDDuke Children's Hospital

Durham, NC

Dean R Hess PhD RRTMassachusetts General Hospital

Harvard Medical School

Boston, MA

PEEP: Bringing theEvidence to the Bedside


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16 yo with Crohns Disease

Immunosuppressed(mercaptopurine)

CMV pneumonia and diffuse

alveolar hemorrhage by BAL Febrile and pancytopenic (WBC

2K; HCT 26%; Plt 89K)

Intubated for severe hypoxemiawith tachypnea and dyspnea

Ventilator: VCV, VT 250 mL(6 mL/kg PBW), I:E 1:2, rate 26,

PEEP 14 cm H2O, FiO2 0.60

ABG: pH 7.41, PaCO2 41 torr,PaO2 64 torr


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The goal of PEEP in this patient is to:

A. Increase PaO2

B. Decrease FiO2

C. Decrease risk of VILI


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Preventing Overdistention and

Collapse Injury

Lung Protective Ventilation

V

OL

U

M

E

V

OL

U

M

E

PressurePressure

Limit Distending Pressure

Add PEEP

Limit Vt

Add PEEPAdd PEEP


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Few topics generate more controversy!

What is the role of PEEP in the reduction /prevention of VILI?

What is the role of PEEP with lung protective

ventilatory strategies?

What is optimal PEEP? Does it really exist?

How do you select the best PEEP for yourpatient?


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Edema in Rat Lungs after Ventilation

14/0 45/10 45/0

Webb HH et al. Am Rev Respir Dis. 1974;110:556-565.


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Does PEEP recruit alveoli?

Or, just prevent de-recruitment


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Inspiratio

n

Exhalation

Zone of

Atelectasis

Zone ofOverdistention

IdealPEEP


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53 patients: conventional vs. protective ventilation Conventional: lowest PEEP for acceptable

oxygenation and VT 12 mL/kg

Protective: PEEP above the lower inflection pointon the PV curve, VT < 6 mL/kg, recruitment

maneuvers, PCV

28 day mortality: protective-ventilation 38% vs.conventional-ventilation 71% (p< 0.001).

N Engl J Med 1998;338:347


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Control (n = 50): VT 911 mL/kg PBW,PEEP > 5 cm H2O

Pflex / LTV (n = 53): VT 58 mL/kg PBW,PEEP at Pflex +2 cm H2O

ICU mortality: 32% in Pflex/LTV group vs. 53% in

control group (p= 0.04)

Crit Care Med 2006; 34:1311


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A. Lower tidal volume only

B. Higher PEEP only

C. Combined effect of PEEP and tidal

volumeD. Unknown

Was the mortality difference in theAmato and Villar trials due to lowertidal volume, higher PEEP, or both?


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N Engl J Med 2000; 342:1301

861 ALI/ARDS patients (10 centers)

6 vs. 12 mL/kg PBW (VCV, Pplat 30 cm H2O)

25%in mortality with smaller tidal volume

Number-needed-to-treat: 12 patients


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ALVEOLI (Assessment of Low tidal Volume and

elevated End-expiratory volume to Obviate Lung Injury)

2 PEEP levels; VT 6 mL/kg PBW

Oxygenation and respiratory system compliancewere improved withPEEP

Stopped at 549 patients for futility

No safety concerns

N Engl J Med 2004;351:327


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Target VT 6 mL/kg PBW Control (n=508): Pplat 30 cm H2O (VCV), lower PEEP

Intervention (n=475): Pplat 40 cm H2O (PCV),

recruitment maneuvers (40 s at 40 cm H2O),initial PEEP 20 cm H2O

No significant difference in hospital mortality

Meade, JAMA 2008;299:637


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Target VT 6 mL/kg PBW Control (n=382): low PEEP (5-9 cm H2O)

minimal distension strategy

Experimental (n=385): PEEP set to achieve Pplat28-30 cm H2O (recruitment strategy);PEEP 163 cm H2O on day 1

No significant difference in mortality, butimproved lung function; reduced duration ofmechanical ventilation and organ failure

Mercat, JAMA 2008;299:646


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Why did these studies fail to show a

mortality benefit?

A. They were underpowered

B. Higher PEEP does not help

C. PEEP strategies were incorrect

D. Harm from higher Pplat offsets benefit ofPEEP

E. Unknown


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Benefit of Higher PEEP Offset by Higher Pplat?

LowerPEEP

HigherPEEP

6mL/kg

P

PlatorPEEP

(cmH2

0)

6 mL/kgNon-

recruitable 6 mL/kgRecruitable

Injury>

Benefit

Benefit>

Injury


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68 ALI/ARDS patients; chest CT at airwaypressures of 5, 15, and 45 cm H2O

Potentially recruitable lung varied

On average, 24% lung could not be recruited

Patients with a higher percent of potentially

recruitable lung had

oxygenation andrespiratory-system compliance, anddead space

N Engl J Med 2006;354:1775


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N Engl J Med 2006;354:1775


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FiO2 0.3 0.3 0.3 0.3 0.3 0.4 0.4 0.5 0.5 0.5 0.6 0.7 0.8 0.9 1.0

PEEP 5 8 10 12 14 14 16 16 18 20 20 20 20 20 20-24

FiO2 0.3 0.4 0.4 0.5 0.5 0.6 0.7 0.7 0.7 0.8 0.9 0.9 0.9 1.0

PEEP 5 5 8 8 10 10 10 12 14 14 14 16 18 20-24

Assess lung recruitabilityPaO2/FiO2 < 150 on 5 cm H2O PEEP

compliance ordeadspace withPEEP?

no

yes

Ramnath, Clin Chest Med 2006;27:601


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Optimal PEEP by Compliance

15 normovolemic ventilated patients

with acute lung injury O2 transport anddeadspace

correlated with compliance

Optimal PEEP varied; 0-15 cm H2O PMVO2 increased from PEEP 0 to the

PEEP resulting in maximum O2transport, but thenat higher PEEP

Compliance may be used to indicatethe PEEP likely to result in optimumcardiopulmonary function.

PEEP

Suter, N Engl J Med 1975;292:284


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0 10 20 30 400

0.4

0.8

1.2

1.6

normal

ARDS

airway pressure (cm H2O)

volumeabove

FRC(liters)

lower inflectionpoint

upper inflectionpoint

0 10 20 30 400

0.4

0.8

1.2

1.6

normal

ARDS

airway pressure (cm H2O)

volumeabove

FRC(liters)

lower inflectionpoint

upper inflectionpoint

Pressure-Volume Curve


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Rotta, J Pediatr (Rio J) 2003;79(Suppl 2):S149


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Owens, Stigler, Hess; Clin Chest Med 2008; 29:297


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Issues with Static PV Curves

Requires sedation / paralysis

Difficult to identify inflection points(Harris, AJRCCM, 2000) May require esophageal pressure to separate lung

from chest wall effects (Mergoni, AJRCCM, 1997;Ranieri, AJRCCM, 1997)

Deflation limb may be more useful than inflation limb(Holzapfel, Crit Care Med, 1983; Hickling, AJRCCM, 2001)

Pressure-volume curves of individual lung units notknown (Hickling, AJRCCM, 1998)

Role of static PV curve for setting PEEP

currently unknown!


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Decremental PEEP Trail

Theoretically attractive, but unproven!

Hickling, AJRCCM 2001;163:69 Richard, Critical Care2004, 8:163


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Esophageal Balloon Catheter

Benditt, Respir Care 2005; 50:68


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Setting PEEP for Acute Lung Injury

0 cm H2O: likely harmful

8-15 cm H2O: appropriate in most patients

> 20 cm H2O: seldom necessary

PEEP should be selected in the context ofprevention of ventilator induced lung injury.

The benefit of precise setting of PEEP isunproven.


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Cardiorespiratory Economics

O2 Supply = O2 Delivery = DO2

DO2 = cardiac output x oxygen content

O2 content = (1.34 x Hgb x O2 sat) + (0.003 x PaO2)


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Determinants of Oxygen Delivery

Hgb (O2 capacity)O2 binding (SaO2)

O2 dissolved (PaO2)Oxygen Content

Contractility

Afterload

Preload

Stroke Volume

Heart Rate

Cardiac Output

O2Delivery


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Effects on RV

thoraxRA

RV

PA

positive

pressureventilation

Right Ventricular Filling


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PPV increases right atrial pressure

spontaneous breathing

RAP= mean systemic venous pressure

Right AtrialPressure

PSV

Systemic Venous Return

00

00 Max

Systemic Venous Return

RV Preload


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How does increasing PEEP affect PVR?

A. Increases PVR

B. Decreases PVR

C. Either is possible


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Lung VolumeLung Volume

PVRPVR

Large VesselsLarge Vessels

AtelectasisAtelectasis

Effect of Lung Volume on PVR


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PVRPVR

Small VesselsSmall Vessels

AtelectasisAtelectasis

OverexpansionOverexpansion



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PVRPVRTotal PVRTotal PVR



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5)PVR

(d-sec/cm

Cheifetz. CCM. 1998.

1000

1500

2000

2500

3000

3500

4000

4500

5000

10 15 20

PEEP 5 PEEP 10

Tidal Volume (mL/kg)

Overdistention and PVR


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CardiacOutput

(mL/min)

Cheifetz. CCM. 1998.

500

550

600

650

700

750

800

850900

950

1000

10 15 20

PEEP 5 PEEP 10

Tidal Volume (mL/kg)

Overdistention and PVR


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0

100

200

300

400

500

600

0 5 10 15 20 25

PaO2 vs. PEEP

Pa

O2(torr)

PEEP (cm H2O)

overdistend

collapse


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Cardiac Output vs. PEEP

2

2.5

3

3.5

4

4.5

5

5.5

0 5 10 15 20 25

PEEP (cm H2O)PEEP (cm H2O)

overdistend

collapse

CO

(l/min)

CO

(l/min)


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DO2 vs. PEEP


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0

100

200

300

400

500

600

0 5 10 15 20 25

0

100

200

300

400

500

600

0 5 10 15 20 25

PaO2 vs. PEEPPaO2 vs. PEEP

DO2 vs. PEEPDO2 vs. PEEP

Optimize O2 delivery


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Setting the Ventilator

Ventilator-InducedLung Injury

Gas Exchange

Patient Comfort Hemodynamics


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20 yo female with ALL

Immunosuppressed lastChemoTx 10 days ago

Adenoviral pneumonia

Febrile and pancytopenic (WBC2K; hematocrit 25; platelets 89K)

Intubated for severe hypoxemia

with tachypnea and dyspnea Vent: PCV, PIP 32 cm H2O,

VT 6 mL/kg PBW, I:E 1:2, PEEP14 cm H2O, rate 26, FiO2 0.60

ABG: pH 7.41, PaCO2 41 torr,PaO2 64 torr


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The goal of PEEP in this patient is to:

A. Increase PaO2

B. Decrease FiO2

C. Decrease risk of VILI


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Setting the Ventilator

Ventilator-InducedLung Injury

Gas Exchange

Patient Comfort Hemodynamics

Documents

PEEP Cheifetz (Egypt) 3-09 (Final Version)