ARDS Guidelines

1
ARDS Guidelines

• Dr. George John,
• Critical Care,
• Christian Medical College,
• Vellore

2
Causative Factors in ARDS
PRIMARY INJURY
HOST RESPONSE
CONSEQUENCES OF THERAPY
3
SPECTRUM OF LUNG INJURY
ALI
ARDS
Cardiogenic pulmonary oedema
P/F RATIO lt 200
Altered Starlings Forces
P/F RATIO 200 - 300
4
Pulmonary Changes

• Alveolar Flooding
• Interstitial inflammation
• Atelectasis
• Early Exudative Phase lt 1 week
• Late Fibro Proliferative Phase gt 1 week

5
Guidelines

• Oxygenation
• Ventilation
• Position
• Fluid management
• Miscellaneous

6
Oxygenation

• Lowest FiO2
• - to keep PaO2 55 80mm Hg
• Increase Alveolar Recruitment degree of
  penetration of gas into poorly / nonaerated lung
  regions
• - PEEP
• - recruitment manoeuver
• - inverse ratio ventilation
• Prone positioning ( proning )
• NO (Nitric Oxide)

7
The Pressure Profile
Peak Pressure
Plateau Pressure
Mean Pressure
PEEP
8
Ventilation

• VENTILATION
• Volume Control mode IE ratio 11 13
• - Tidal Volume 6ml / kg
• - Plateau Pressure lt 30cm H2O
• - High rate if CO2 high up to 35 / minute
• Measures to decrease CO2 production (sedation,
  decrease temperature)
• Permissive hypercapnoea
• If pH lt 7.30 use HCO3 infusion
• Other techniques
• ?Tracheal gas insufflation (TGI) / Expiratory
  washout (EWO)
• (use humidified gas only)
• ? Pressure Control Mode with pressure 30
• - many with less pressure needed for
  ventilation in the study
• - study done with VC mode

9
PositionPRONING

• Ventilation in the prone position improves
  oxygenation but most clinical studies have not
  shown that prone ventilation improves outcome. In
  a study of paediatric patients (2 weeks to 18
  years of age) with acute lung injury, prone
  positioning did not significantly reduce
  ventilator-free days or improve clinical outcome.
  
• However, in a study published in 2006, prolonged
  prone positioning (at least 20 hours a day) in
  patients greater than 18 years of age showed that
  it was safe and may reduce mortality.

10
Fluid ManagementLiberal versus Conservative

• Conservative strategy
• maintain a low target filling pressure (CVP of
  less than 4mm Hg or PAOP
• of less than 8 mm Hg)
• versus
• Liberal strategy maintain higher filling
  pressure CVP 10 14mm Hg or
• PAOP 14-18mm Hg. This was achieved by a
  combination of bolus fluid
• administration, use of frusemide or dobutamine,
  depending on the
• perfusion, urine output , measured filling
  pressures and cardiac output (if
• available).
• Result
• There was no significant difference in mortality
  (25.5 in the conservative group vs. 28.4 in the
  liberal group). However, the conservative
  strategy improved the oxygenation index, lung
  injury score, increased the number of ventilator
  free days and days not spent in ICU. The
  conservative strategy did not increase the
  incidence or prevalence of shock during the
  study. In addition, the conservative strategy did
  not increase the use of dialysis during the first
  60 days.

11
Monitoring

• In a landmark study published in 2006, the use of
  PA catheter guided therapy did not improve organ
  function or survival as compared to CVC guided
  therapy. The PA catheter was associated with more
  complications (twice as many catheter related
  complications, predominantly arrhythmias) than
  CVC guided therapy.

12
Cardiovascular

• Haemoglobin 8 10 g
• Maintain Cardiac Output
• Judicious fluids
• Use inotropes as needed

13
Other Modalities

• Steroids
• Earlier study
• Evidence that use of steroids after the first
  week of ARDS improves prognosis significantly.
• In 2006
• No benefit in the use of methylprednisolone
  after the first week of ARDS. Use of sterods
  after 14 days of ARDS was associated with
  increased mortality at 60 days. This was in spite
  of the steroid therapy and improving ventilator
  free shock free days during the first 28 days.
  Methyprednisolone did not increase infectious
  complications but was associated with a higher
  rate of neuromuscular weakness.
• Nitric Oxide
• No benefit
• Beta agonists
• The beta agonist lung injury trial (BALTI) has
  shown that treatment with
• intravenous albutamol (15ug / kg / hr) reduces
  extravascular lung water (EVLW)
• in patients with ALI / ARDS with a reduction in
  plateau pressures at Day 7.
• The effect on EVLW started at 48 hours. Patients
  receiving intravenous
• salbutamol had a higher incidence
  ofsupraventricular arrhythmias these were not
• sustained as the dose of salbutamol was modified
  in these patients. There was
• no improvement in mortality with the use of
  salbutamol however the study was
• not Powered to detect a difference in mortality.

14
Imitators

• Acute Interstitial Pneumonia (AIP)
• Acute Eosinophilic Pneumonia
• Acute BOOP
• DAH
• Acute HP

15
Suspecting Imitators

• Common features fever, cough, myalgia, raised
  WBC, CRP, LDH
• Distinguishing features BAL, Lung Biopsy,
  Response to steroids and prognosis (in some)

16
Possible Approach

• Early BAL infectious agents, differential WBC
  count
• Serological tests for autoimmune disease, CK
  (polymyositis)
• Haematocrit serial
• Ferritin (increased in adult Stills)
• Renal function
• Urine microscopy
• Lung biopsy if BAL is inconclusive, after
  considering risk vs. benefit. Specially important
  in DAH (vasculitis induced) necessary for
  immunofluorecent staing for ABMA.
•  The suggestion to start all these patients
  initially on steroids for 3 days till the BAL
  results / other tests are available is
  controversial and needs to be evaluated in a RCT.

17
References - 1

• Bernard GR et al. The American European Consensus
  Conference on ARDS. Am J Respir Crit Care Med
  1994 149 818 824
• Meduri et al. Corticosteroid rescue treatment of
  progressive fibroproliferation in late ARDS.
  Patterns of response and predictors of outcome.
  Chest 1994 105 1516 1527
• Meduri GU et al. Effect of prolonged
  methylprednisoloine therapy in unresolving acute
  respiratory distress syndrome. A randomized
  controlled trial. JAMA 1998 280 159 165
• Brun-Buisson C and Brochard L. Corticosteroid
  therapy in acute respiratory distress syndrome.
  Better late than never? JAMA 1998 280 182 183
• Cook D et al. A comparison of Sucralfate and
  Ranitidine for the prevention of upper
  gastrointestinal bleeding in patients requiring
  mechanical ventilation. N Engl J Med 1998 338
  791 - 79
• Amato MBP et al. Effect of protective ventilation
  strategy on mortality in the acute respiratory
  distress syndrome. N Engl J Med 1998 338 347 -
  354
• Stewart TE et al. Evaluation of a ventilation
  strategy to prevent barotrauma in patients at
  high risk for acute respiratory distress
  syndrome. N Engl J Med 1998 338 355 361
• Richecoeur J et al. Respiratory washout versus
  optimisation of mechanical ventilation during
  permissive hypercapnoea in patients with severe
  acute respiratory distress syndrome. Am J Respir
  Crit Care Med. 1999 160 77 - 85
• The Acute Respiratory Distress Syndrome Network.
  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 2000 342 1301 1308
• Gattinoni L et al. Effect of prone positioning on
  the survival of patients with acute respiratory
  failure. N Engl J Med 2001 345 568 573
• Nuckton T et al. Pulmonary dead space fraction as
  a risk factor for death in the acute respiratory
  distress syndrome. N Engl J Med 2002 346 1281
  1286
• New Management strategies in ARDS. Editor Levy
  MM. Critical Care Clinics, January 2002  
• Jindal SK et al. Adult respiratory distress
  syndrome in the tropics. Clin Chest Med 2002 23
  445 455

18
References - 2

• Kopp R et al. Evidence based medicine in the
  therapy of the acute respiratory distress
  syndrome. Intensive Care Medicine 2002 28 244
  245
• The ARDS Clinical Trials Network. Effects of
  recruitment manoeuvers in patients with acute
  lung injury and acute respiratory distress
  syndrome ventilated with high positive end
  expiratory pressure. Crit. Care Med. 2003 31
  2592 2597
• Marini JJ. Are recruiting maneuvers needed when
  ventilating acute respiratory distress syndrome?
  Crit. Care Med. 2003 31 2701 2702
• Barbas CSV. Lung recruitment menoeuvers in acute
  respiratory distress syndrome and facilitating
  resolution. Crit. Care Med. 2003 31 (Suppl)
  S265 S271
• Marini J Gattinoni L. Ventilatory management of
  acute respiratory distress syndrome a consensus
  of two Crit. Care Med 2004 32 250 255
• The Margaux IV Conference on Critical Illness
  Acute Lung Injury Understanding the mechanisms
  of injury and repair. Crit. Care Med. 2003 31
  (Suppl) S183 S342
• Schwarz MI et al. Imitators of the ARDS.
  Implications for diagnosis and treatment. Chest
  2004 125 1530- 1535
• Mancebo J et al. A multicenter trial of prolonged
  prone ventilation in severe acute respiratory
  distress syndrome. Am J Respir Crit Care Med.
  2006 173 1233 1239
• Barrett NA Kam PCA. Transfusion-related lung
  injury a literature review. Anaesthesia 2006
  61 777 785
• ARDS Clinical Trials Network. Pulmonary Artery
  versus Central Venous Catheter to guide treatment
  of Acute Lung Injury. The New Engl. J Med. 2006
  354 2213 - 2224
• ARDS CLINICAL Trials Network. Comparison of two
  fluid management strategies in Acute Lung Injury.
  The New Engl J Med. 2006 354 2564 2575
• Rivers EP. Fluid Management Strategies in Acute
  Lung Injury Liberal or Conservative or both?
  The New Engl J Med. 2006 354 2598 2600