Bài giảng hồi sức cấp cứu.Dung tích của phổi 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 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 Bài giảng hồi sức cấp cứu.Dung tích của phổi Ventilator induced lung injury HFOV Caring for the Baby in Adults Baby Lung Sitting on Top of a Consolidated Lung Tidal Volumes of 610 mlkg based on weight Tidal Volumes of 2050 mlkg based on open lung units Histology is similar to infant lung injury

Ventilator Induced Lung

Injury

Ventilator Induced Lung Injury

• Barotrauma

• Volutrauma

• Stretch Injury

• Biochemical Injury

Ventilator Induced Lung Injury

• Tearing at Bronchio-Alveolar Junction as lung is recruited and

allowed to collapse

• Most occurs in

Effect of 45 cmH2O PIP

Control 5 min 20 min

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

Ventilator Induced Lung Injury

Stretch Injury

Alveolar Space A-C Membrane

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)

Ventilator Induced Lung Injury

• Volutrauma

• Caused by cycling of the lung (change in surface area), independent of pressure required

• Alters Surfactant function

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

Ventilator Induced Lung Injury

Premature baboon model

Coalson J Univ Texas San Antonio

Ventilator Induced Lung Injury

Premature baboon model

Coalson J Univ Texas San Antonio

Alveolar Edema and

Hyaline Membrane

Hemorrhage and Edema

on weight

• Tidal Volumes of 20-50 ml/kg

based on open lung units

• Histology is similar to infant lung injury

Ventilator Induced Lung Injury

• Adult Acute Respiratory Failure– Atelectasis

– Overdistended airways and alveoli

– Cellular accumulation– Hyaline

Membranes Lamy ARRD 1976; 114:267

Ventilator Induced Lung Injury

• Adult ARDS late stage lung structural changes

• Enlarged air space

• Septal destruction

• Fibrotic lesions

ARDS Pulmonary Injury

• Hyaline Membrane Formation

• Inflammatory Cell Migration

• Volutrauma - Increased Protein Leak, Atelectasis, etc

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

ARDS Pulmonary Injury

• Pulmonary Vascular Obliteration

• Chronic Lung Disease

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

• Thromboxane

• TNF (Tumor Necrotizing Factor)

• Complement Proteins

• Interleukin-1,8

Pulmonary Injury Sequence

• There are two injury zones during mechanical ventilation

• Low Lung Volume Ventilation tears adhesive surfaces

• High Lung Volume Ventilation over-distends, resulting in

Ventilator Induced Lung Injury

Twenty Years of One Year Follow

Up of Lung Function (DLCO)

in ARDS Survivors

Suchyta MR, ERS 1997

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

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

Ventilator Induced Lung Injury

Ventilator Induced Lung Injury

Control animal histology

Ventilator Induced Lung Injury

HFOV animal histology

Ventilator Induced Lung Injury

CMV animal histology

Ventilator Induced Lung Injury

• HFOV Stimulates Significantly Less Neutrophil Activity Than CMV

• Neutrophil Activity Has a Role in the Genisis of

ARDS, Releasing Active Oxygen Species,

Proteinases and Arachidonic Acid Metabolites

Sugiura M, JAP 1994; 77:1355

Ventilator Induced Lung Injury

• HFOV produces less inflammatory markers than CMV

Ventilator Induced Lung Injury

• Activation of alveolar macrophages and pro-inflammatory cytokines play a pivotal role in Ventilator Induced Lung Injury

Takata M, AJRCCM 1997;

156:272

Risk Factors for ARDS

• Metabolic Events - Pancreatitis, Uremia

• Systemic Mediator Release Associated Diseases

– Disseminated Intravascular Coagulopathy– Cardiopulmonary Bypass Anaphylaxis– Extrapulmonary Infection Transfusion Reaction

“Open up the lung up

and keep it