ARDS for the ED Physician

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• ARDS for the ED Physician
• Rafi Israeli, MD
• Assistant Professor of Medicine
• Emergency services Institute
• Cleveland Clinic Foundation
• Cleveland, Oh

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Conflicts of Interest

• None

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ARDS for the ED Physician

• History
• Clinical Course
• Pathophysiology
• Causes
• Incidence
• Therapy

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History

• 1967 Ashbaugh, et al. described Adult
  Respiratory Distress Syndrome
• Respiratory Distress
• Cyanosis
• Hypoxemia despite oxygen
• Diffuse infiltrates on Chest Xray
• Drawback No specific Criteria

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History

• 1988 Murray, et al. expanded the definition of
  ARDS using a 4- point scale, based on
• Extent of Chest Xray abnormalities
• Severity of Hypoxia PaO2/FiO2
• Amount of PEEP
• Search for cause of ARDS
• Drawback Does not predict Outcome
• Does not exclude Cardiogenic Pulm Edema

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History

• 1994Ameican- European Consensus Conference
  Committee
• Renamed Acute Resp Distress Syndrome
• Described ARDS as syndrome of inflammation and
  permeability
• Coined the term ALI as a precursor to ARDS

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History

• 1994Ameican- European Consensus Conference
  Committee Criteria
• Acute Onset
• Bilateral infiltrates
• PAWP 18
• ALI PaO2/FiO2 300
• ARDS PaO2/FiO2 200
• Drawback Does not specify cause

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Clinical CourseAcute Phase

• Rapid Onset
• Exudates
• Consolidations
• Respiratory failure
• Hypoxemia refractory to O2
• Inflammation (even in non-edematous lung)
• IL-1,6,8,10, Cytokines
• Diminished Lung compliance

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Clinical CourseAcute Phase

• Patchy infiltrates Coalesce
• Air Bronchograms
• Pulmonary Hypertension
• Intrapulmonary Shunting
• Endogenous Vasoconstrictors
• Hyperadrenergic State

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Clinical CourseFibrosing Alveolitis

• Persistent Hypoxia
• Pulmonary Fibrosis
• Worsening Compliance
• Neovascularization
• Pulmonary Hypertension
• Macrophages clear neutrophils
• Chronic Inflammation

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Clinical CourseRecovery

• Active transport of Na into interstitium
• Endocytosis of Protein
• Transcytosis of Protein
• Alveolar Epithelial type II cells proliferate
• Apoptosis of remaining neutrophils?

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The Normal Alveolus (Left-Hand Side) and the
Injured Alveolus in the Acute Phase of Acute Lung
Injury and the Acute Respiratory Distress
Syndrome (Right-Hand Side)
Ware L and Matthay M. N Engl J Med
20003421334-1349
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Pathophysiology

• Alveolar Epithelial Basement Membrane Breakdown
• Damage to Vascular Endothelium
• Third Spacing of Protein-Rich fluid
• Flooding of Alveoli
• Shock
• Type II cells damaged
• Less Surfactant
• Diminished fluid removal

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Pathophysiology

• Platelet Aggregation
• Microthrombi ? Shunting
• Fibrosis from disorganized repair of intersitium

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Causes

• DIRECT LUNG INJURY

• INDIRECT LUNG INJURY

• Aspiration
• Pneumonia
• Pulmonary Contusion
• Toxic Inhalation
• Near-Drowning

• Sepsis
• Shock
• Extrathoracic Trauma
• Multiple Fractures
• Burns
• Eclampsia
• Pancreatitis
• DIC

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Incidence Outcome

• 20-75 per 100,000
• 30 mortality
• Recovery may take 6-12 months
• Residual Restriction
• Obstruction
• Gas- Exchange Abnormalities
• Reduced Quality of Life

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Therapy

• Treat Underlying Cause
• Antibiotics
• Surgery
• Enteral Feedings
• Peyers Patches
• Less Catheter Sepsis
• Supportive ARDS Network (ARDSNet)

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TherapyMechanical Ventilation

• The Problem Ventilator- Induced Lung Injury
• High volumes and pressures Stress
• Overdistension Alveolar Cracking
• Cyclic Opening and closing of atelectatic alveoli
• Cause increased permeability and alveolar damage

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TherapyMechanical Ventilation

• The Problem Oxygen Toxicity
• Free Radicals
• Oxygen Washout and De-Recruitment
• High FiO2 can lead to further alveolar damage

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• Intubation almost always necessary
• In past, goal was to normalize pH, PaCO2, PaO2
• High volumes and pressures were used
• Worse outcomes

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TherapyLung-Protective Mechanical Ventilation

• Amato et al. 1998, Effects of a protective-
  ventilation strategy on mortality in the acute
  respiratory distress syndrome. N. Engl. J. Med.
  338347-54
• 53 pts with early ARDS
• Compared conventional ventilation of 12ml/kg to
  protective 6ml/kg
• Low PEEP. PaCO2 35-38
• Improved survival at 28 days
• Higher percentage of ventilator weaning
• Less barotrauma

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TherapyLung-Protective Mechanical Ventilation

• The Acute Respiratory Distress Network. 2000.
  Ventilation with lower tidal volumes as compared
  with traditional tidal volumes for acute lung
  injury and the acute respiratory distress
  syndrome. N. Engl. J. Med. 3421301-8
• Larger Trial. 861 patients
• Compared 12 ml/kg vs. 6ml/kg ventilation.
• Plateau pressures 50 cm H2O vs. 30 cm H2O.
• Trial ended early
• 39.8 mortality vs. 31 mortality
• THIS HAS CHANGED CLINICAL PRACTICE

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Therapy

• PEEP

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TherapyPEEP

• http//content.nejm.org/content/vol354/issue17/ima
  ges/data/1839/DC1/NEJM_Slutsky_1839v1.swf

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TherapyPermissive Hypercapnea

• Minute VentilationRR x Tidal Volume
• High PEEP Levels (12-15cm H2O)
• Low Tidal Volumes and Peak and Plateau Pressures
  result in Hypercapnea
• Carvalho et al.(1997) found the following
• Increased HR
• Increased PA pressures
• Increased Cardiac Output
• Respiratory Acidosis
• But no adverse Outcomes

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TherapyOptimal PEEP

• Gattinoni et al. 2006.Lung Recruitment in
  Patients with ARDS. N. Engl. J. Med. 3541775-86.
• What is optimal PEEP in individual Patient?
• PEEP in non-recruitable lung causes
  overdistension barotrauma and alveolar stress
• Study measured age of recruitable lung using CT

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TherapyOptimal PEEP

• Gattinoni et al. 2006.Lung Recruitment in
  Patients with ARDS. N. Engl. J. Med. 3541775-86
• Inclusion Criteria
• PaO2FiO2 lt 300
• Bilateral pulmonary infiltrates
• PACWP lt 18
• PEEP Trial Prior to CT, high airway pressures and
  PEEP were applied.
• Lung weight measured by CT

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Frequency Distribution of Patients According to
the Percentage of Potentially Recruitable Lung
(Panel A) and CT Images at Airway Pressures of 5
and 45 cm of Water from Patients with a Lower
Percentage of Potentially Recruitable Lung (Panel
B) and Those with a Higher Percentage of
Potentially Recruitable Lung (Panel C)
Gattinoni L et al. N Engl J Med 20063541775-1786
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TherapyOptimal PEEP

• Gattinoni et al. 2006.Lung Recruitment in
  Patients with ARDS. N. Engl. J. Med. 3541775-86
• Results
• In patients where higher age of recruitable
  lung, mortality higher, worse gas exchange.
• Use of PEEP in patients with lower age of
  recruitable lung was harmful.
• Results were variable

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Bedside Peep Adjustment

• Increase the Peep and Plateau pressure
  constant recruitment.
• If increase in plateau pressure is proportional
  to PEEP increase overdistension

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TherapySteroids

• Pros
• Inflammatory nature of disease
• Treatment of Fibrosing alveolitis

• Cons
• Historically, no benefit shown with high dose
  steroids
• Increased infection

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TherapySteroids

• Tang, et al.2009. Use of corticosteroids in
  acute lung injury and acute respiratory distress
  syndrome A systematic review and meta-analysis.
  Crit Care Med 3751594-1602
• Systematic review of studies with low-dose
  steroids
• Primary outcome Hospital mortality
• Secondary outcomes length of ventilation, ICU
  LOS, Lung injury score, PaO2FiO2.

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TherapySteroids

• Tang, et al.2009. Use of corticosteroids in
  acute lung injury and acute respiratory distress
  syndrome A systematic review and meta-analysis.
  Crit Care Med 3751594-1602
• Results
• 9 studies reviewed (4 RCT, 5 cohort)
• 648 total subjects, mean age 51
• 40-250mg/d Methylprednisolone
• 7-32 days

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TherapySteroids

• Tang, et al.2009. Use of corticosteroids in
  acute lung injury and acute respiratory distress
  syndrome A systematic review and meta-analysis.
  Crit Care Med 3751594-1602
• Mortality Trend toward reduction.
• RTC P0.08. Cohort P0.06.
• Combined P0.01
• Morbidity Reduced ventilation 4 days Reduced
  ICU stay 4 days
• Improved Disease Severity Scores
• Improved PaO2FiO2

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TherapySteroids

• Tang, et al.2009. Use of corticosteroids in
  acute lung injury and acute respiratory distress
  syndrome A systematic review and meta-analysis.
  Crit Care Med 3751594-1602
• Adverse Effects No difference in infection,
  musculoskeletal complications, GI bleeding, major
  organ failure.

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TherapyFluids

• Can diuresis or fluid restriction minimize
  alveolar edema?
• ARDSNet 2006. Comparison of Two-Fluid Management
  Strategies in Acute Lung Injury. N. Engl. J. Med.
  35424 2564-75
• Prospective, RCT comparing liberal fluid use vs.
  conservative (more Lasix, less boluses).
• More positive fluid balances in liberal vs.
  conservative .
• Subjects were intubated, PaO2FiO2lt 300
• Protocol initiated 43 h post ICU admission.

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TherapyFluids

• ARDSNet 2006. Comparison of Two-Fluid Management
  Strategies in Acute Lung Injury. N. Engl. J.
  Med. 35424 2564-75
• Hemodynamics Lower intravascular pressures in
  conservative group
• Lung Function Lower PEEP, plateau pressures,
  shortened ventilation time in conservative group
• Metabolic Higher creatinine values in
  conservative.
• Mortality No difference in 60 day mortality

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TherapyPA Catheter

• 1994 American- European criteria require the
  absence of LA hypertension
• PAC information often ambiguous
• Practitioners often misinterpret PAC info
• Associated Risks

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TherapyPA Catheter

• The Acute Respiratory Distress Network. 2006. PAC
  versus CVC to Guide Treatment of Acute Lung
  Injury. N. Engl. J. Med. 35421. 2213-24
• Included intubated pts with PaO2FiO2lt300.
• Bilateral infiltrates
• Excluded ALI gt 48 Hours, dialysis, irreversible
  conditions
• All pts were ventilated with low tidal volumes

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TherapyPA Catheter

• The Acute Respiratory Distress Network. 2006.PAC
  versus CVC to Guide Treatment of Acute Lung
  Injury. N. Engl. J. Med. 35421. 2213-24
• Death within 60 days was similar
• Ventilator- Free days similar
• No difference if patients were in shock
• More Arrhythmias in PAC group

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DiagnosisBNP

• Bajwa et al. 2008. Crit. Care. Med. Found that
  BNP Levels are elevated in ARDS.
• Levitt et al 2008. Crit Care found that BNP
  levels do not distinguish CHF from ARDS.
• Reasons
• Myocardial Dysfunction in sepsis
• Direct inflammation on myocytes
• RA and RV stretch in ARDS

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DiagnosisProcalcitonin

• Marker that indicates likelihood of having a
  systemic response to a bacterial infection
• One study found it to be a Marker for mortality
  in ARDS

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DiagnosisUltrasound

• Copetti et al. Cardiovascular Ultrasound 2008,
  616 

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NIVPPV

• Zhan, et al. 2011. Early use of noninvasive
  positive pressure ventilation for acute lung
  injury A multicenter randomized controlled
  trial. Crit Care Med
• RTC
• 40 patients randomized to high flow oxygen vs.
  NIVPPV
• Less intubations in NIVPPV (P lt0.04)
• Total organ system failure less in NIVPPV group
  (Plt0.001)

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NIVPPV

• No good studies assesing NIVPPV as a means to
  prevent intubation in ARDS.

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Prognosis

• Prognosis primarily depends on underlying cause
  of lung injury
• Sepsis has worst prognosis
• Pneumonia has intermediate prognosis
• Trauma has best prognosis

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Surviving Sepsis Guidelines

• 6 cc/ kg Tidal Volume
• End- inspiratory plateau pressures lt 30
• Hypercapnea is acceptable