Imaging of Acute Lung Injury Sujal R. Desai, MBBS, MD ESTI SPEAKER
Background
Imaging tests vital in Ix of lung injury
The Imaging of Acute Lung Injury
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Increased numbers of patients surviving
Plain CXR both common and vital; CT and other tests providing a supportive “problem-solving” role
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Sujal R Desai King s College Hospital, London
Aims
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Further insights from CT…?
Chest Radiography on ICU The Benefits of Digital Radiography
Consider (briefly) the “basic” radiological aspects of imaging critically ill-patients
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Review the h specifics f off imaging in acute lung l injury (ALI) & acute respiratory distress syndrome (ARDS)
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Discuss the value of and pathophysiological insights from CT (± other imaging tests) in ALI & ARDS
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Imaging on the ICU
Imaging on the ICU
The Issue of the Routine Chest Radiograph
The Issue of the Routine Chest Radiograph
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A daily routine in many units
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Important for •
Detection of complications
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Monitoring progress
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1 2
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15-65% show clinically unsuspected changes / 15progression
Henschke CI Bedside chest radiography: diagnostic efficacy Radiology 1983;149:23-26 Strain DS Value of routine daily chest x-rays in the medical intensive care unit. Crit Care Med 1985;13:534-536
Day 1
Day 5
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Imaging in Lung Injury
Some Key Questions
Some Key Questions
What is/are the principal roles of CXR, CT, US in the management of patients with ALI/ARDS?
What is/are the principal roles of CXR, CT, US in the management of patients with ALI/ARDS?
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SUNDAY
Imaging in Lung Injury
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Does CT add anything…?
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Is there any prognostic information in imaging tests?
Does CT add anything…?
Is there any prognostic information in imaging tests?
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Imaging in Lung Injury Principal Roles of Radiological Tests
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Diagnosis
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Monitoring progress / resolution
The Diagnosis of ALI/ARDS
• Detection of (clinically-unsuspected) complications
DG et a.l Acute repiratory distress in adults Lancet 1967;2:319-323
Bernard et al. The American-European consensus conference on ARDS: definitions, mechanisms, relevant outcomes, and clinical trial coordination Am J Respir Crit Care Med 1994;149:818-824
Bernard et al. The American-European consensus conference on ARDS: definitions, mechanisms, relevant outcomes, and clinical trial coordination Am J Respir Crit Care Med 1994;149:818-824
Desai SR et al. Acute respiratory distress syndrome caused by pulmonary and extrapulmonary injury: a comparative CT study Radiology 2001;218:689-693
ARDS
ARDS
Variable CT Appearances
Variable CT Appearances PULMONARY
ATYPI CAL Desai SR et al. Acute respiratory distress syndrome caused by pulmonary and extrapulmonary injury: a comparative CT study Radiology 2001;218:689-693
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EXTRAPULMONARY
TYPICAL
Desai SR et al. Acute respiratory distress syndrome caused by pulmonary and extrapulmonary injury: a comparative CT study Radiology 2001;218:689-693
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ARDS
Pulmonary versus Extrapulmonary ARDS
Unilateral ARDS
PULMONARY
SUNDAY
ARDS
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EXTRA PULMONARY
Desai SR et al. Acute respiratory distress syndrome caused by pulmonary and extrapulmonary Injury: A Comparative CT Study Radiology 2001;218:689-693
Padley SPG et al. Asymmetric ARDS following pulmomary resection: CT findings initial observations Radiology 2002;223:468-473
Imaging in ALI/ARDS Recurrent Pneumothorax and Chest Drains 47 Pneumthoraces ARDS=21; non-ARDS=26
Monitoring Progress
ARDS
Non-ARDS
14/21 recurrent
2/26 recurrent
Detection of Complications HORIZONTAL
TUBE
12/14 ARDS; 2/2 non-ARDS
1 Heffner JE et al Recurrent penumothoraces in ventilated patients despite ispilateral chest tubes Chest 1995;108:10531058
Imaging in ALI/ARDS
Imaging in Lung Injury
Malpositioned Chest Drains a few examples!
Some Key Questions
• What is/are the principal roles of CXR, CT, US in the management of patients with ALI/ARDS? •
Does CT add anything…?
Is there any prognostic information in imaging tests?
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Imaging in ALI/ARDS
Imaging in ALI/ARDS
Quantification of data on CT images
Quantitative CT
KEY PRIN CIPLES
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Hyperinflated (~ > -900 HU)
De ns ity
Normal Aeration ((~ - 500 to -900 900 HU)
CT Dens ity of lun g de te rm ine d by relative am ount of air
Air on CT is black
Poorly aerated (~ -100 to -500 HU)
Decr eas e in r elative am ount o f air ma nifest s a s increa si ng whitenes s
Non aerated (~ -100 to 100 HU)
Imaging in ALI/ARDS
Imaging in ALI/ARDS
Categorising lung CT patterns
Pathophysiological Relationships LOW COMPLIANCE
1 Gattinoni L et al. What has computed tomography taught us about the acute respiratory distress syndrome Am J Respir Crit Care Med 2001;164:1701-1711
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Imaging in ALI/ARDS
Imaging in ALI/ARDS
Lung Recruitment
Lung Recruitment
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Gattinoni L et al. Lung recruitment in patients with the acute repiratory distress syndrome N Engl J Med 2006;354:17011775-1786
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Gattinoni L et al. What has computed tomography taught us about the acute repiratory distress syndrome Am J Respir Crit Care Med 2001;164:1701-1711
Gattinoni L et al. Lung recruitment in patients with the acute repiratory distress syndrome N Engl J Med 2006;354:17011775-1786
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Imaging in ALI/ARDS
Why the AP Gradient ?
Why the AP Gradient A Normal Phenomenon?
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Imaging in ALI/ARDS
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Pelosi P et al. Vertical gradient of regional inflation in adult respiratory distress syndrome Am J Respir Crit Care Med 1994;149:8-13
Imaging in ALI/ARDS
Imaging in ALI/ARDS
Cardiac Compression
Cardiac Compression
Malbouisson LM et al. Role of the heart in the loss of aeration characterizing lower lobes in acute respiratory distress sndrome Am J Respir Crit Care Med 2000;161:2005-2012
Malbouisson LM et al. Role of the heart in the loss of aeration characterizing lower lobes in acute respiratory distress sndrome Am J Respir Crit Care Med 2000;161:2005-2012
Imaging in ALI/ARDS
Imaging in ALI/ARDS
Cardiac Compression Effects of Prone Positioning
Beneficial Effects of Dependent Atelectasis ? VENTRAL “Unprotected”
DORSAL “Protected” Albert RK et al. The prone position eliminates compression of the lungs by the heart Am J Respir Crit Care Med 2000;161:1660-1665
Desai SR et al. Acute respiratory distress syndrome: CT abnormalities at long-term follow-up Radiology 1999;210:2935
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Imaging in ALI/ARDS
Imaging in ALI/ARDS
Lung Sequelae in Survivors
Lung Sequelae in Survivors
Desai SR et al. Acute respiratory distress syndrome: CT abnormalities at long-term follow-up Radiology 1999;210:2935
Desai SR et al. Acute respiratory distress syndrome: CT abnormalities at long-term follow-up Radiology 1999;210:2935
Imaging in ALI/ARDS
Imaging in ALI/ARDS
Lung Sequelae in Survivors
Fibrosis in ARDS
Desai SR et al. Acute respiratory distress syndrome: CT abnormalities at long-term follow-up Radiology 1999;210:29-35
Ichikado K et al. Acute interstitial pneumonia: comparison of high-resolution computed tomography findings between survivors and nonsurvivors Am J Respir Crit Care Med 2002;165:1551-1556
Imaging in ALI/ARDS
Imaging in ALI/ARDS
Fibrosis in ARDS
Early Fibrosis in ARDS N-TERMINAL PROCOLLAGEN PEPTIDE III
MITOGENIC ACTIVITY OF BALF in ARDS vs CONTROLS Ichikado K et al. Acute interstitial pneumonia: comparison of high-resolution computed tomography findings between survivors and nonsurvivors Am J Respir Crit Care Med 2002;165:1551-1556
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Marshall RP et al. Fibroproliferation occurs early in acute respiratory distress syndrome and impacts on outcome Am J Respir Crit Care Med 2000;162:1783-1788
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Imaging in ALI/ARDS
Some Key Questions
Fibrosis and Prognosis in ARDS
SUNDAY
Imaging in ALI/ARDS
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What is/are the principal roles of CXR, CT, US in the management of patients with ALI/ARDS? •
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Does CT add anything…?
Is there any prognostic information in imaging tests?
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Ichikado K et al. Acute interstitial pneumonia: comparison of high-resolution computed tomography findings between survivors and nonsurvivors Am J Respir Crit Care Med 2002;165:1551-1556
Imaging in ALI/ARDS
Imaging in ALI/ARDS
Fibrosis and Prognosis in ARDS
Fibrosis and Prognosis in ARDS
Ichikado K et al. Acute interstitial pneumonia: comparison of high-resolution computed tomography findings between survivors and nonsurvivors Am J Respir Crit Care Med 2002;165:1551-1556
Ichikado K et al. Acute interstitial pneumonia: comparison of high-resolution computed tomography findings between survivors and nonsurvivors Am J Respir Crit Care Med 2002;165:1551-1556
Imaging in ALI/ARDS
Imaging in ALI/ARDS
The Unanswered Questions
Closing Remarks
Morphological differences between ALI and ARDS?
If so, do these predict outcome, duration on ventilator?
Prediction of likely steroidresponsiveness ?
Imaging tests are integral to the management of critically-ill patients
Plain chest radiography is the “workhorse” investigation; routine probably acceptable for ICU patients…
CT (+ others) useful supporting role
CT continues to provide pathophysiological and prognostic insights in lung injury
