Circulatory Shock, types and stages, compensatory mechanisms
3 lung and thorax
1. Lung & thorax
SAH & RNSH 2011
Critical Care Ultrasound Course
Thanks to:
Dr Paul Atkinson
Dr Bishr Faheem
Dr Daniel Lichtenstein
2. Scanning the lung
• Why scan the lung?
• Probe & scanner settings
• Technique
• Landmarks
• US findings
• Terminology: the lung profiles
• Matching the findings to the disease
• Sticking needles & tubes in the lung
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3. Why scan the lung?
• Diagnosis
• Air in pleura: PTX
• Fluid in pleura: blood, pus
• Fluid in lung tissue: APO/ pneumonia /
ARDS
• Consolidated lung tissue: pneumonia /
contusion / infarct (PE) / cancer
• Procedures
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4. Why bother?
• Lung US is more accurate than CXR for:
• PTX (>95% versus 50%)
• Pleural fluid (20ml versus 200ml)
• APO sens 97%, spec 94%, acc 95%
• PE?? Sens 74% … 81% if add DVT
• It’s also
• Faster (2 min versus 19 min)
• Safer
• Repeatable 4
6. Patient position
! No need to sit patient up (eg trauma)
! In fact, accuracy for PTX is improved if
lying flat… just harder to get round the
back for pleural fluid
! Air rises
! Fluid sinks
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7. Probe
! Ideally the curved probe
! Linear array no anatomical info
! Phased array poor image quality
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8. Preset
! Abdo / FAST
! Not the commercial ‘lung’ settings
! Turn off filters
! Multibeam / compounding
! Tissue harmonics
! Why? You are looking for artefacts
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9. Depth
! Close up consolidation? = 5cm
! Just sliding / A / B lines? = 10cm
! Base of lung / diaphragm? = 15cm
! Making sure rockets are rockets? =
15cm
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10. Probe position
! Sagittal
! Right angles to the ribs
! Makes sure that the landmarks (rib
shadows) stay in view
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12. Look between the ribs
RIB
RIB
PLEURAL LINE (WHERE THE ACTION IS)
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13. So:
! Curved probe
! FAST / abdo preset
! 10-15cm depth
! Turn off fancy filters
! Sagittal / long axis of patient
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14. Where will I scan?
Depends on clinical context
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15. The basic principle
! Air rises " scan highest point of the
chest
! Fluid sinks " scan lowest point
! Some diseases are patchy (eg
pneumonia, ARDS) " scan as much of
the lung as possible (at least look at
each lobe)
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16. Where will I scan?
! Cardiac arrest: highest point on each side
! Shock: 2 anterior (BLUE) points on each side
! Breathless: 3 points on each side
! Add 1 posterior (PLAPS) point
! Thorough look: as much of each lung as
possible (improves accuracy)
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26. PLAPS point
! ‘Postero- Lateral Alveolar / Pleural
Syndrome’
! What the %$#% ???
! Posterolateral = round the back
! Alveolar syndrome = consolidation
! Pleural syndrome = pleural fluid
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27. PLAPS point
! The PLAPS point is the lowest point of
the lung
! The Morison's Pouch of the
thorax’ (thanks to Dr Chris Wong)
! So this is where you find pleural fluid
! If there’s no fluid here, there’s no fluid
anywhere in the thorax!
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28. How to find the PLAPS point
! It’s the posterior continuation of the
lower BLUE point (as far around as you
can get the probe)
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31. Tip: watch out for the abdomen!
! If you scan the liver / spleen & think you’re still
above the diaphragm, it will resemble consolidation
! ESP if you are using linear probe
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36. NB: ‘normal lung’
! Pleural line looks like a ‘curtain’ sliding
back & forth
! Sparkle = scatter from air in lung
! You don’t really seeing normal lung at
all
! If it looks like liver:
! mirror
! hepatization
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38. What am I looking for?
! Pleural fluid
! Pleural sliding
! A lines: reverb artefact from pleural line
! B lines: hyperechoic reverberation effect
from air/water interface
! C: consolidation
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44. Pleural fluid: caveats
! Pleural vs pericardial fluid (pericardial =
delimited by descending aorta)
! Peritoneal fluid (where’s the diaphragm?)
! Small traces of fluid: easy to miss
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48. A, B & Z lines
! A lines = horizontal & static =
reverberation artefact from pleura
! B lines = vertical & move with resps
(prev ‘comet tails’) = thick vertical lines
which reach to edge of screen &
obliterate A lines
! Z lines = vertical, fade quickly, don’t
move with resps
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53. B lines
Vertical artefacts
Air/fluid mix in interlobular septa
Equivalent of Kerley B lines
Not seen in PTX
Even 1 B line rules out PTX at that site
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54. B lines
Vertical
Bright
Obliterate A lines
Don’t fade!
Reach all the way to the edge of the
screen!
1 or 2 per lung field is OK
3 or more = ‘rockets’
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56. Z lines
! ill defined
! DON’T move with respiration
! DON’T erase the A lines
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57. Lung rockets
‘When several B lines are visible in
a single scan, the pattern
evokes a rocket at lift-off, and
we have adopted the term ‘lung
rockets’’ (Lichtenstein p106)
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62. Top Tip
Up to 1/3 normal patients have rockets in
dependent regions
So if you see rockets in PLAPS points, it
doesn’t matter!
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63. Lung rockets = wet lungs
! Just in the bases = normal
! In all windows = cardiogenic oedema
! Patchy, with spared areas = non
cardiogenic oedema / widespread
pneumonia
! Localised = pneumonia / chronic
interstitial diseases eg fibrosis
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69. Applications of lung rockets
! Diagnosis
! Is it his CCF or COPD playing up today?
! Fluid status
! is this guy with a crap LV overloaded today?
! Guiding fluid resuscitation
! Fill him up until the rockets appear
! Dialyse him until the rockets disappear
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70. Validation
! Volpicelli et al, Am J Emerg Med 2006 (24):
689-696
! N=300 (75 had AIS)
! Combined gold standard incl 1 month
follow up
!
sens
spec
! Rockets
85.7%
97.7%
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71. Just remember
! Not all vertical lines are B lines
! Z lines = puny
! pseudo-rockets with subcut emphysema (don’t
move with respiration, & can’t see normal rib
shadow above them)
! Not all rockets = fluid
! widespread pneumonia
! widespread fibrosis
! rockets can be normal in lowest intercostal space
! Posterior lung rockets can be normal in supine
patients
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95. Stratosphere sign
! M-mode = motion mode
! If something isn’t moving, it’s a
straight line
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96. 2. No B lines
• i.e. the A’ profile (air is dry)
• Even a single B line rules out PTX
• Because B lines = air/fluid interface
• Absent sliding + B line = LUNG
• EG not ventilating
• EG pneumonia
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97. 3. The lung point sign
! Specific to PTX
! the site where normal lung gives way to PTX
! on one side of the image sliding is present
! on the other side it is absent.
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99. What if there’s no lung point sign?
there might still be a massive PTX which has
collapsed the entire lung. Go back to the
clinical picture & decide whether you need
to go ahead & decompress the chest.
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100. Can I trust lung US for PTX?
If you are just starting out:
! If you want to find all PTX: get a CT
! Stable patient, Negative CXR, positive
EFAST: get a CT … or ask a friend to scan
! Unstable patient, Negative CXR, positive
EFAST: decompress the chest
! Rushing to OT/ chopper, neg CXR, pos
EFAST: warn anaesthetist or insert ICC
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107. Alveolar consolidation
! If you can see lung tissue, it ain’t normal!
! It ain’t aerated
! Collapse
! Consolidation
! Atelectasis
! Contusion
! Infarction (PE)
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110. Terminology
• A profile = A lines (or no lines), sliding preserved
• A’ profile = A lines (or no lines), sliding absent
• B profile = lung rockets in all windows, sliding
preserved
• B’ profile = lung rockets in all windows, sliding
reduced / absent
• A/B profile = patchy rockets alternate with normal
areas
• C profile = areas of consolidation
• PLAPS positive = consolidation / effusion at bases
• PLAPS negative = anything else at bases (A lines /
B lines / rockets)
111. A word of advice about the A profile
• All A lines = A profile
• No lines seen? Still = A profile
• Up to 2 B lines per window are OK! Still = A profile
• Z lines? Still = A profile
133. Normal lungs
• A profile
• Up to 2 B lines per window are OK
• PLAPS negative
134. Pneumothorax
• A’ profile = A lines (or no lines), sliding absent
• There are no B lines at all on that side
• There will be a lung point unless lung is completely
collapsed
135. Acute cardiogenic pulmonary oedema
(APO)
• B profile =
• lung rockets in all windows
• lung sliding preserved
136. ARDS or pneumonia
B’ profile =
• lung rockets in all windows
• lung sliding reduced / absent
• And pleural line may be irregular
A/B profile
C profile
A profile anteriorly, PLAPS positive
137. Pulmonary embolus
A profile anteriorly, PLAPS positive or negative i.e.
lungs can look normal
Sometimes C profile (pulmonary infarcts)
140. Chest drains/
thoracocentesis
! Same rationale as central line placement
! Ensures you don’t stick ICC in the liver
! Tricks:
! Get patient to take maximal inspiration &
expiration
! Scan in 2 planes
! Scan in same position you’ll insert ICC
! Use real time US
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142. Lung US: top tips
! Curved probe / FAST preset
! At right angles to the ribs
! Is there sliding? Tip: compare sides
! A or B or C?
! PLAPS or no PLAPS?
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