Bài giảng hồi sức cấp cứu.Dung tích của phổi Ventilator induced lung injury

Ventilator Induced Lung
Injury


Ventilator Induced Lung Injury
• Barotrauma
• Volutrauma
• Stretch Injury
• Biochemical Injury

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Ventilator Induced Lung Injury
• Barotrauma
• Air leaking into
pleural space
• Air leaking into
interstitial space
(PIE)
• Tearing at
Bronchio-Alveolar
Junction as lung is
recruited and
allowed to
collapse
• Most occurs in
dependent lung
zones (transition
zone)

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Effect of 45 cmH2O PIP

Control

5 min

20 min
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Ventilator Induced Lung Injury
• Stretch Injury
• Alters capillary
transmural pressures
• Changes in transmural
pressure causes breaks
in capillary endo and
epithelium
• Increases leak of
proteinacious material
• Promotes Atelectasis

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Ventilator Induced Lung Injury
Stretch Injury

Alveolar
Space
A-C
Membrane

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Ventilator Induced Lung Injury
• Rodents ventilated
with three modes:
• High Pressure
(45 cmH2O), High
Volume
• Low Pressure
(negative pressure
ventilator), High
Volume
• High Pressure
(45 cmH2O), Low
Volume (strapped
chest and
abdomen)
Dreyfuss,D ARRD
1988;137:1159

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Ventilator Induced Lung Injury
• Volutrauma
• Caused by cycling of the
lung (change in surface
area), independent of
pressure required
• Alters Surfactant function
• Promotes Atelectasis
• Increases capillary leak of
proteinacious material
• Promotes Atelectasis

Dreyfuss,D ARRD 1988;137:1159

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Ventilator Induced Lung Injury
• Hyaline Membrane
Disease is not really a
disease, it’s the result
of volume cycling the
lungs
• CMV produces
consolidation, over
inflation and hyaline
membrane formation
• HFOV uniformly
inflates the lung
without hyaline

membrane formation
Meredith K, JAP 1989;
66:2150

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Ventilator Induced Lung Injury

Premature baboon model
Coalson J. Univ Texas San Antonio

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Ventilator Induced Lung Injury

Premature baboon model
Coalson J. Univ Texas San Antonio

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Alveolar Edema and
Hyaline Membrane

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Hemorrhage and Edema

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Adult ARDS
• HFOV - Caring for the
Baby in Adults
• Baby Lung Sitting on
Top of a Consolidated
Lung
• Tidal Volumes of
6-10 ml/kg based
on weight
• Tidal Volumes of
20-50 ml/kg
based on open
lung units
• Histology is similar
to infant lung injury
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Ventilator Induced Lung Injury
• Adult Acute
Respiratory Failure
– Atelectasis
– Overdistended
airways and
alveoli
– Cellular

accumulation
– Hyaline
Membranes

Lamy ARRD 1976; 114:267

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Ventilator Induced Lung Injury
• Adult ARDS late
stage lung structural
changes
• Enlarged air
space
• Septal
destruction
• Fibrotic lesions

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ARDS Pulmonary Injury
Sequence
• Phase 1 Early Exudative Treatment
• Endo/Epithelial Damage
• Type 1 Alveolar Cell Injury and/or Loss
• Capillary Congestion
• Interstitial/Alveolar Edema, Hemorrhage
• Protein Accumulation

• Surfactant Deactivation
• Atelectasis
• Hyaline Membrane Formation
• Inflammatory Cell Migration
• Volutrauma - Increased Protein Leak,
Atelectasis, etc.

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ARDS Pulmonary Injury
Sequence
• Phase 2 Proliferative (Day 5-10)
• Proliferation of Type 2 Cells
• Fibroblast Migration
• Interstitial Collagen Formation
• Increased Dead Space
• Decreased Compliance
• Increased Pulmonary Vascular Resistance

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ARDS Pulmonary Injury
Sequence
• Phase 3 Fibrotic (Day 10-14)
• Lung Destruction
• Emphysematous Changes
• Fibrosis
• Pulmonary Vascular Obliteration

• Chronic Lung Disease

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Ventilator Induced Lung Injury
• Biochemical Injury
• Biochemical agents
(mediators) attack the
lung
• Recruit fibrotic
proliferation cells to
the lung
• Atelectasis promotes
release of chemical
mediators
• Mediators released in
the lung can attack
other organ systems

• Cells

• Macrophages
• Endothelial and
Epithelial Cells
• Platelets
• Neutrophils

• Mediators

• Cytokines
• Leukotrienes
• PAF (Platelet
Activating Factor)
• Thromboxane
• TNF (Tumor
Necrotizing Factor)
• Complement
Proteins
• Interleukin-1,8

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Ware and Matthay NEJM 342 (18): 1334

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Pulmonary Injury Sequence
• There are two injury
zones during mechanical
ventilation
• Low Lung Volume
Ventilation tears
adhesive surfaces
• High Lung Volume
Ventilation overdistends, resulting in
“Volutrauma”
• The difficulty is finding

the “Sweet Spot”
Froese AB, Crit Care Med
1997; 25:906

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Ventilator Induced Lung Injury
Twenty Years of
One Year Follow
Up of Lung
Function (DLCO)
in ARDS
Survivors

Suchyta MR, ERS 1997

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Ventilator Induced Lung Injury
• HFOV with Surfactant as
Compared to CMV with
Surfactant in the Premature
Primate
– HFOV resulted in
• Less Radiographic
Injury
• Less Oxygenation
Injury

• Less Alveolar
Proteinaceous Debris

Jackson C
AJRCCM 1994; 150:534

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Ventilator Induced Lung Injury
• High Lung Volume Strategies
with HFOV
• Extended Surfactant
Activity
• Normalized Lamellar
Body Phospholipid levels
• Improved lung mechanics
• All Conventional Ventilator
Strategies
• Resulted in Death or
Decreased Surfactant
Performance
Froese A, ARRD 1993;
148:569

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