Acute respiratory distress syndrome

1
Acute respiratory distress syndrome

• Prof.M.K.Arora
• Dr.Lenin
• Dr.Prabhu

www.anaesthesia.co.in anaesthesia.co.in_at_gmail.c
om
2
History

• Described by Ashbaugh et al in 1967
• Acute respiratory distress in adults Ashbaugh
  DG et al .Lancet 1967
• Adult respiratory distress syndrome Term was
  coined by Petty TL, Ashbaugh DG. Chest 1971

3
Other names

• Adult hyaline-membrane disease
• Adult respiratory insufficiency syndrome
• High output respiratory failure
• Congestive atelectasis
• Hemorrhagic lung syndrome
• Da Nang lung
• Stiff-lung syndrome
• Shock lung
• White lung
• Taylor RW et al Res Medica 1983117-21.

4
Definition

1. Lung injury score
2. Modified lung injury score
3. NAECC Definition

5
Definition

• Three part expanded definition
• Part 1- acute or chronic on course
• Part 2- lung injury score
• Part 3- associated risk factors such as sepsis,
  pneumonia, aspiration or major trauma
• Murray JF, Matthay MA 1988

6
Lung injury score

• Chest radiograph
• Hypoxemia score
• PEEP score
• Respiratory compliance score

7
Lung injury score

• CXR
• No consolidation ..0
• Confined to 1 quadrant 1
• 2 quadrant .2
• 3 quadrant .3
• 4 quadrant .4

• PaO2/FiO2
• gt300..0
• 225-299 1
• 175-224 2
• 100-174 3
• lt100..4

8
Lung injury score

• PEEP
• (when mechanically ventilated)
• lt5 cm H2O..0
• 6-8 cm H2O 1
• 9-11 cm H2O ..2
• 12-14 cm H2O ....3
• gt15 cm H2O ...4

• Compliance
• (when available)
• gt80 ml/ cm H2O ..0
• 60-79 ml/ cm H2O ...1
• 40-59 ml/ cm H2O 2
• 20-39 ml/ cm H2O 3
• lt19 ml/ cm H2O ...4

9
Lung injury score

• Add the sum of each component and divide by the
  number of components used
• 0- No lung injury
• 0.1-2.5 Mild to moderate lung injury
• gt2.5 Severe lung injury (ARDS)

10
(No Transcript)
11
Modified lung injury score

• PaO2/FiO2 lt174
• Bilateral infiltrates on chest x-ray

12
NAECC Definition 1994,1998

• Onset- acute and persistent
• Oxygenation criteria
• PaO2/FiO2 300 for ALI
• PaO2/FiO2 200 for ARDS
• Exclusion criteria-
• PAOP 18 mmHg
• Clinical evidence of left atrial hypertension
• Radiographic criteria-
• bilateral opacities consistent with pulmonary
  edema
• Bernard GR et al 1994

13
Incidence
Study Criteria Incidence
NHU task force 1972 75
Canary islands 1989 PaO2/FiO2 110 PaO2/FiO2 150 1.5 3.5
Utah 1995 PaO2/FiO2 110 4.8-8.3
Berlin 1995 LIS gt2.5 LIS gt1.75-lt2.5 3.0 17.1
Scandinavia 1999 PaO2/FiO2 300 PaO2/FiO2 200 LIS gt2.5 17.9 13.5 7.6
Rubenfled 2003 Current criteria (ALI) 64.2
14
Asso. clinical disorders-direct

• Less common
• Inhalational injury
• Pulmonary contusion
• Fat emboli
• Near drowing
• Reperfusion injury

• Common
• Aspiration pneumonia
• Pneumonia

15
Asso. clinical disorders-indirect

• Common
• Sepsis
• Severe trauma
• Multiple fractures
• Multiple blood transfusion

• Less common
• Acute pancreatitis
• Cardiopulmonary bypass
• DIC
• Burns
• Head injury

16
(No Transcript)
17
Risk factors predictive of mortality

• Liver dysfunction/ cirrhosis
• Sepsis
• Non pulmonary organ dysfunction
• Age gt than 65
• Organ transplantation, HIV, active malignancy,
  chronic alcoholism, mechanim of lung injury

18
Pathogenesis

• Lung injury
• The pulmonary response to a broad range of
  injuries occuring either
• -directly to the lungs
• -or as the consequence of injury or
• inflammation at other sites in the
• body

19
Acute Exudative Phase

• Exudative phase
• Commencing within 24 hrs
• 1-7 days
• Diffuse alveolar damage
• Diffuse Microvascular injury
• Neutrophil infiltration
• Edematous alveolar wall
• Hyaline membrane

20
Acute Exudative Phase

• Basement membrane disruption
• Type I pneumocytes destroyed
• Type II pneumocytes preserved
• Surfactant deficiency
• inhibited by fibrin
• decreased type II production
• Microatelectasis/alveolar collapse
• Self limited or progresses

21
(No Transcript)
22
(No Transcript)
23
(No Transcript)
24
Proliferative phase

• For 3-10 days
• Type II pneumocyte
• proliferate
• differentiate into Type I cells
• reline alveolar walls
• Fibroblast proliferation
• interstitial/alveolar fibrosis

25
(No Transcript)
26
Fibrotic Phase

• 1-2 weeks
• Characterized by
• local fibrosis
• vascular obliteration
• Repair process
• resolution vs fibrosis

27
Pathophysiology

• Interstitial / alveolar edema
• Severe hypoxemia
• due to intra-pulmonary shunt
• High ventilatory demands
• high metabolic state
• increased VD/VT
• decreased lung compliance
• Pulmonary HTN

28
Clinical features- CHF ARDS

• Anxiety, dyspnea, tachypnea
• Reduced lung volumes
• Decreased lung compliance
• ABG- respiratory alkalosis, hypoxemia
• CXR

29
Favour of ARDS

• ARDS risk factors
• PCWP
• BALF is proteinaceous and inflammatory
• Pathological findings

30
Diagnosis

• Based on clinical criteria
• no diagnostic tests
• Confirmatory tests
• PA catheter
• PAWP normal/reduced
• bronchial secretion proteinserum protein
• ratio gt 70 - 80
• CT scan-heterogenous pattern with a predominance
  of infiltration in the dependent region

31
(No Transcript)
32
(No Transcript)
33
Differential Diagnosis

• Cardiogenic pulmonary edema
• Bronchopneumonia
• Hypersensitivity pneumonitis
• Pulmonary hemorrhage
• Acute interstitial pneumonia (Hamman-Rich
  Syndrome)

www.anaesthesia.co.in anaesthesia.co.in_at_gmail.c
om