Estrategia de pulmón abierto

Edgar Jiménez, MD, FCCM

Director – UCI y Co-Chairman Medicina CríticaOrlando Regional Medical Center

Profesor Asociado de MedicinaUniversity of Florida, Florida State University &

University of Central Florida

PresidenteFederación Mundial de Sociedades de Medicina Crítica

Estrategia de “Pulmón Abierto” Utilizando Presiones Transpulmonares

2º Seminario de Ventilación Mecánica - VAFO

Asociación Panameña de Medicina Crítica y Terapia Intensiva

Hospital Santo Tomás, Ciudad de Panamá, Julio de 2011

Disclosures

• Research:

– NASA

– CareFusion®

– CCCTG & CIHR

Objectives

Using in vivo videomicroscopy will demonstrate the anatomical, physiological and pathophysiological findings of:

• Normal lungs• Acutely injured lungs• Lung recruitment using Ptp• Intra-abdominal hypertension

• 1966• “Oscar” for Special

Effects• Isaac Azimov• Richard Fleischer• Raquel Welch

Fantastic Voyage

Raquel Welch

Real-life“Fantastic Voyager”

Gary Nieman, BA

Director:

Critical Care Translational Research LaboratoryORMC, Orlando, FL

Cardiopulmonary and Critical Care LaboratorySUNY, Syracuse, NY

Labs in Syracuse, NYand Orlando, FL

How come?

In vivo videomicroscopy

Concept of RACE:Repetitive alveolar closing and expansion

Mechanisms of VILI

• Barotrauma• Volutrauma• Biotrauma• Atelectrauma

To understand:abnormal alveolar mechanics

We must first understand:

normal alveolar mechanics

“The end”of the Bronchial

Tree

F. Possmayer, PhD. U. of Western Ontario

How do we breathe?

Weibel et al Respir Physiol 1985

Alveolar Duct

Alveolar Duct

Expiration

Inspiration

Normal alveolar dynamics

G Nieman, SUNY

G Nieman, SUNY

Alveoli:Not Just a Bunch of Grapes

Prange H: Adv Physiol Educ 2003

Alveolar IndependenceStructural Support

Mead: JAP 1970

Honeycomb-like structural support

Hiroko & Nieman, SUNY 2005

Stressed alveolar sac

G Nieman, SUNY

G r a v i t y

Courtesy of Dr. Marcelo Amato

G r a v i t y


Stress

Strain

G r a v i t y


G r a v i t y


Pendeluft

Stresses on the Epithelium during Fluid Displacement

Bilek AM et al. J Appl Physiol 2003;94:770-783

Rigid airwayCourtesy of Dr. Marcelo Amato

Stresses on Epithelium during Airway Opening

Bilek AM et al. J Appl Physiol 2003;94:770-783

Flexible airway


VIAS YS He a lthca re , Inc.

Wa re a nd Ma ttha y NEJ M 342 (18): 1334

Capillary LeakCapillary LeakCapillary Leak

Fu Z, JAP 1992; 73:123

Capillary LeakCapillary LeakCapillary Leak

Fu Z, JAP 1992; 73:123

Steinberg J.et al. Am J Resp Crit Care Med 2004

Heterogeneous Lung Injury

Normal lung: In vivo Microscopy Histology + IHC

Injured lung:In vivo MicroscopyHistology + IHC

Steinberg et al. AJRCCM. 2004;169:57-63


Stable Alveoli

Unstable Alveoli

Low PEEP Group(3)


Stable Alveoli

Alveoli StabilizedWith PEEP

High PEEP Group(15)

PEEP = improves oxygenation

PEEP = improves oxygenation

It’s more than that!

PEEP = stabilizes alveoli

PEEP = decreases RACE

PEEP = decreases VILI

ARDSNet (NHLBI)

• NEJM, May – 2000• 10 University Centers• Criteria:

– Bilateral infiltrates– Intubation and mechanical ventilation– PaO2/FiO2 <300

28 Day Survival

0

0.2

0.4

0.6

0.8

1

0 7 14 21 28Days after study entry

Proportion Surviving 12

ml/kg

6 ml/kg

ARDSNet NEJM, 2000

Respiratory Cycle

Ppeak

PEEPTrigger

Pplat

Initial table for FiO2 & PEEP

ARDSNet NEJM, 2000

ARDSNet demonstrated:

An outcome changeprimarily associated to a

change in ventilatory strategy(LV)

A big question:

Is the ARDS Net Protocol enough?

Not really

• We may not know the true transpulmonary pressure (Ptp)

• Timid and arbitrary PEEP scale

Meta-Analysis Based on

• ALVEOLI• LOVS• EXPRESS

Briel, M. et al. JAMA 2010;303:865-873.

Clinical Outcomes in Patients Stratified by Presence of ARDS at Baseline

% HPEEP

LPEEP

P H PEEP

L PEEP

P HPEEP

LPEEP

P

D Hosp 32.9 35.2 .25 34.1 39.1 .049 27.2 19.4 .07

D ICU 28.5 32.8 .01 30.3 36.6 .001 19.6 16.8 .71

RESC 12.2 18.6 < .001 13.7 21.3 < .001 4.4 7.3 .70

D RESC 7.5 11.3 < .001 8.6 13.2 < .001 1.6 3.6 .15

All Pts ARDS Non-ARDS

Briel, M. et al. JAMA 2010;303:865-873.

Volume

Pressure

Zone ofOverdistention

“Safe”Window

Zone ofDerecruitmentand Atelectasis

Injury

Injury

Optimized Lung Volume “Safe Window”

• Overdistension – Edema fluid accumulation– Surfactant degradation– High oxygen exposure– Mechanical disruption

• Derecruitment– Atelectasis– Inflammatory response– Surfactant inhibition – Local hypoxemia– Compensatory overexpansion

Froese: Crit Care Med 1997

CT 1 CT 2CT 3

Froese: Crit Care Med 1997

How do We Open the Lung and Keep it Open?


• Open:

Recruitment maneuver


• Open:

Recruitment maneuver

• Keep it open:

PEEP or HFOV

Ware and Matthay NEJM 342 (18): 1334

Current Ventilation Practices

• Volume Ventilation, Low VT, PEEP

• Pressure Control Ventilation– PEEP, Inverse I:E Ratio

• VCV or PCV with PEEP adjusted by Ptp• Non-Conventional Ventilation

– APRV/Bi-Level– HFOV

• Pronation, iNO• ECMO

How do we know we have achieved OL-PEEP?

How do we do it?• ARDS Net• ALVEOLI, LOVS, EXPRESS• Decremental PEEP Trial• Pes and Ptp• Volumetric Capnography• Auscultation• Ultrasound• Respiratory Impedance Pletysmography• Electrical Impedance Tomography• HFOV - TOOLS

Can we do better?

Let’s talk about pressure…

Let’s talk about pressure…

and the trumpet player

How much airway pressure can a trumpet player generate?

Trumpet player

Bouhuys A: Physiology and musical instruments. Nature. 1969. 221:1199-1204

Bouhuys A: Physiology and musical instruments. Nature. 1969. 221:1199-1204

Cook. J Applied Phys. 1964. 1016

Answer: 100-120 cm H2O

Cook. J Applied Phys. 1964. 1016

So…

Why don’t we see more ALI and ARDS in these players?

Answer:

Because they keep the Ptp within tolerable limits

Answer:


with

the use of their respiratory muscles

Let’s go to extremes ofairway pressure

Paw at sea level:

Paw at sea level: 1034 cm H2O

Paw at a 33 ft dive:

Paw at a 33 ft dive: 2068 cm H2O


Add 1034 cm H2O for every 33 ft.

Paw at a 100 ft dive:


So…

Why don’t we see more ALI and ARDS in these divers?

Answer:


Answer:


with

a similar increase in the external environmental pressure

It’s all relative!

<0.5 MPH

17,000 MPH

17,000 MPH

<0.5 MPH

17,000 MPHSuccess!

What is the Paw at 10,000 ft?


795 cm H2O


795 cm H2O

30% lessthan MSL

What is the Paw atMt. Everest’s summit?


285 cm H2O


285 cm H2O

72% lessthan MSL

They can get in LOTS of trouble!

Management of ALI and ARDS using Transpulmonary Pressures

Management of ALI and ARDS using Transpulmonary pressures

• Factors that may alter current recomendations based on ↓Ccw:– Obesity– Edema/anasarca– Intra-abdominal pressure– Pregnancy– Chest wall deformities– Scars

The problem???

• With Pplat, we are measuring only one side of the equation!!!!!

• What happens with patients with compromised compliances?

The problem???

• With Pplat, we are measuring only one side of the equation!!!!!

• What happens with patients with compromised compliances?

• We DON’T KNOW!

Intrathoracic pressures

TRACHEAL PRESSURE

(Ptr)

PROX. AIRWAY PRESSURE (Paw)

PLEURALPRESSURE

(Ppl)(Pes)

ALVEOLAR PRESSURE

(Palv)

Pplat

TRACHEAL PRESSURE

(Ptr)


PLEURALPRESSURE

(Ppl)(Pes)

ALVEOLAR PRESSURE

(Palv)

Ptp

TRACHEAL PRESSURE

(Ptr)


PLEURALPRESSURE

(Ppl)(Pes)

ALVEOLAR PRESSURE

(Palv)

Ptp

TRACHEAL PRESSURE

(Ptr)


PLEURALPRESSURE

(Ppl)(Pes)

ALVEOLAR PRESSURE

(Palv)

Pes

Position of Esophagus and Pleura

Pplat and Ptp

• Kubiak, Jimenez, Silva, Nieman• Marked variability among patients in

abdominal and pleural pressures• For a given PEEP, Ptp may vary

unpredictably from patient to patient.

Malbrain ML et al. Incidence and prognosis of intraabdominal hypertension in a mixed population of critically ill patients: a multiple-center epidemiological study.Crit Care Med 2005;33:315-322.

Talmor D et al. Esophageal and transpulmonary pressures in acute respiratory failure. Crit Care Med 2006;34:1389-1394

Relationship Ptp - Tv

Talmor et al. Crit Care Med, 2006

Ptp

(cm H2O)

Tv(mL/kg)

Figure 1

0

5

10

15

20

25

30

Stage One Stage Two

Increasing IAP

0 0

Vt PEEP

Kubiak, Jimenez, Nieman, J Surg Trials, 2010

Kubiak, Jimenez, Nieman, J Surg Trials, 2010

Jimenez, Nieman ORMC, 2008

Transpulmonary Pressure, Plateau (Ptp-plat)

Increased Ptp :

↓ compliance

↑ negative Ppl

Decreased Ptp :

normal compliance

not assisting on the ventilator

Intrathoracic pressures

Tracheal pressures are measured at distal

end of ET Tube

Ptr (Paw)

Esophageal Pressure Measurements

Connections

Connections

Ptp

• Placed in lower 1/3 of esophagus, above diaphragm

• Measured pressures reflect pleural pressures

Esophageal Balloon

Paw

Pes

Breath Initiation

20

10

0

-10

-20

20

10

0

-10

-20

cm H2O

The Baydur Maneuver

Hypothesis

• Patients with ↑ Ppl with conventional settings:– Underinflation → causes hypoxemia– Raising PEEP to maintain a positive Ptp improves

aeration and oxygenation without overdistention.

Hypothesis

• Patients with ↓ Ppl with conventional settings:– Maintaining low PEEP would keep low Ptp– Prevents overdistention– Minimizing adverse hemodynamic effects of high

PEEP

Beyer J et al: The influence of PEEP ventilation on organ blood flow and peripheral oxygen delivery. Intensive Care Med 1982;8:75-80.

Goal

• To provide sufficient Ptp (Paw - Ppl) to:– Maintain acceptable PaO2

– Minimize repeated alveolar collapse– Minimize overdistention

Ptp = Ptr – Pes

Slutsky AS. Lung injury caused by mechanical ventilation. Chest 1999;116:Suppl:9S-15S.

Methods

• Supine• HOB 30º• Esophageal balloon catheter passed to 60 cm

from incisors– Gentle compression of abdomen

• Then withdrawn to 40 cm– Cardiac artifact

• 1/3 couldn’t be passed into stomach

Talmor D et al. Mechanical ventilation guided by esophageal pressure in acute lung injury. NEJM 2008; 359: 2095-2014

Methods

• Recruitment maneuver– 40 cm H2O X 40 sec.

– Max Ptp-plat < 25 cm H2O

• VT: 6 mL/kg PBW

• PBW:– ♂: 50 + 0.91 X (cm – 152.4)– ♀: 45.5 + 0.91 X (cm – 152.4)


Strategy

• PaO2: 55-120 mm Hg– Or SpO2: 88-98 %

• pH: 7.30-7.45• pCO2: 40-60 mm Hg

• VT: Adjusted to keep Ptp-plat < 25 cm H2O


Strain (dVgas/Vgas0)

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

Stre

ss (

PL

, cm

H2O

)

0

5

10

15

20

25

30

35

40

45

50

55

Stress-strain curve of healthy pigs

Specific Lung Elastance 5.8 cmH2O

Protti A. et al. Am J Respir Crit Care Med. 2011 Feb 4. [Epub ahead of print]

Protti A. et al. Am J Respir Crit Care Med. 2011 Feb 4. [Epub ahead of print]

Strategy

• PCV or VCV• I:E : 1:1 to 1:3• RR: < 35• RM: PRN for suction/disconnection


Table


Table

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

Ptp-PEEP

0 0 2 2 4 4 6 6 8 8 10 10


Study

• Stopped after 61 pts as criteria were met in interim analysis


PaO2/FiO2


Respiratory System Compliance(mL/cm H2O)


VD/VT


PEEP


Ptp - EE


Ptp - PEEP


Pplat


Ptp – PLAT


Ptp – EI


K-M Survival


ARDSNet Lung (ARMA)

Jimenez E, Nieman G, ORMC 2011

Ptp Lung

Jimenez E, Nieman G, ORMC 2011

Talmor presents:

An improvement in oxygenation and compliance with

Ptp significantly lower thanoverestimated Pplat

Talmor presents:

A persistent negative Ptp-PEEP when using the ARDS Net scale

A big question:

Is this enough?

Not really

• Arbitrary PEEP scale• We need to know how to adjust it better• We need to find morbidity/mortality data

What else can we use?

Volumetric Capnography

Terminology

• End-Tidal CO2 (ETCO2)

Peak concentration of CO2 at end exhalation.

• Time-Based Capnography

Concentration of CO2 plotted as a scale

• Volumetric Capnography

Concentration of CO2 integrated with flow.

Zero baseline (A-B)

Rapid, sharp rise (B-C)Alveolar plateau (C-D)

End tidal value (D)

Rapid, sharp downstroke (D-E)

• EtCO2 • Capnogram• RR

Capnography Volumetric CO2

• CO2 Elimination• Deadspace• Alveolar Ventilation• Cardiac Output / Perfusion• Physiologic Vd/Vt

PEEP & VCO2

VCO2 isCO2 elimination

from CO2 production… …in a steady state!!!

Important questions for us:

• Is the pt OK with LVHP (ARDS Net)?• Is the FiO2 > 0.60?

• Is your Pplat > 30 cm H2O?

• Is your Paw > 20 cm H2O?

• Is your Ptp plat> 20 cm H2O?

• PEEP > 15 cm H2O?

• OI > 15?

What’s Next ????

Estrategia de pulmón abierto

Education

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