3 lung and thorax

transcript

Lung & thorax

SAH & RNSH 2011Critical Care Ultrasound Course

Thanks to:Dr Paul AtkinsonDr Bishr Faheem

Dr Daniel Lichtenstein

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

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

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

The Technique

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

Probe! Ideally the curved probe! Linear array no anatomical info! Phased array poor image quality

Preset! Abdo / FAST! Not the commercial ‘lung’ settings! Turn off filters

! Multibeam / compounding! Tissue harmonics

! Why? You are looking for artefacts

Depth! Close up consolidation? = 5cm! Just sliding / A / B lines? = 10cm! Base of lung / diaphragm? = 15cm! Making sure rockets are rockets? =

Probe position! Sagittal ! Right angles to the ribs! Makes sure that the landmarks (rib

shadows) stay in view

Find those ribs

‘RIB’‘RIB’

Look between the ribs

RIBRIB

PLEURAL LINE (WHERE THE ACTION IS)

So:! Curved probe! FAST / abdo preset! 10-15cm depth! Turn off fancy filters! Sagittal / long axis of patient

Where will I scan?

Depends on clinical context

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)

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)

BLUE points & PLAPS points

BLUE points & PLAPS points! What the %$#% ???! Daniel Lichtenstein’s BLUE protocol! BLUE is not an acronym! PLAPS is, though

BLUE points & PLAPS points! Upper BLUE point = upper lobe! Lower BLUE point = middle lobe /

lingula! PLAPS point = lower lobe

Lichtenstein’s BLUE points

Lichtenstein’s BLUE points in theory

Lichtenstein’s BLUE points in practice

Lichtenstein’s PLAPS point

PLAPS point! ‘Postero- Lateral Alveolar / Pleural

Syndrome’! What the %$#% ???! Posterolateral = round the back! Alveolar syndrome = consolidation! Pleural syndrome = pleural fluid

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!

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)

How to find the PLAPS point

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

Tip: Get round as far back as you can!

wrong right

Normal lung

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

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

Pleural fluid

! Site: dependent regions! Appearance:

! black = anechoic (fresh blood, transudate/ exudate)

! echogenic / stuff = blood, exudate! Amount: as little as 20ml! Sensitivity >97%, specificity 99-100%

(Sisley et al, J Trauma 1998)

Pleural fluid

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

Pleural or pericardial fluid?

Duh! Just look all over the thorax

A, B & Z lines

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

A lines

A linesHorizontal artefactsOnly air is present

Present in dry lungsPresent in PTX

B-line

B line

B linesVertical artefacts

Air/fluid mix in interlobular septaEquivalent of Kerley B lines

Not seen in PTXEven 1 B line rules out PTX at that site

B linesVerticalBright

Obliterate A linesDon’t fade!

Reach all the way to the edge of the screen!

1 or 2 per lung field is OK3 or more = ‘rockets’

Z-lines(Note: A line maintained)

Z lines

! ill defined! DON’T move with respiration! DON’T erase the A lines

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)

Lung rockets

3 or more B lines per lung field = ‘rockets’

Not ‘comets’

International consensus dropped the term (terminology is confusing enough already)

Rockets

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!

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

Remember: 1 or 2 B lines are OK. Lung is still dry at that point!

A, B or Z lines? Dry or wet?

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

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%

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

Lung sliding

! Visceral pleura glides on parietal pleura! Why is it important?! A lines + sliding = dry lung = A profile! A lines without sliding = PTX = A’ profile! Rockets + sliding = APO = B profile! Rockets without sliding = ARDS / pneumonia

= B’ profile

Lots of things can prevent lung sliding

! CAL! Apices ! Failure to ventilate

! eg R main stem intubation (L lung doesn’t move)

! Eg pain (chest splinting)! Pneumothorax! Pneumonia & ARDS

Lots of things can prevent lung sliding

! CAL! Apices ! Failure to ventilate

! eg R main stem intubation (L lung doesn’t move)

! Eg pain (chest splinting)! Pneumothorax! Pneumonia & ARDS … ???

How the hell do pneumonia / ARDS reduce lung sliding?

Here’s how:

ARDS/ disseminated pneumonia:Exudate

Proteinaceous‘sticky’

Reduced / absent lung sliding, irregular

pleural lineB’ profile

APO:Transudate

Lung sliding is preserved, smooth

pleural lineB profile

Is sliding preserved?

So how do I diagnose PTX?

Diagnosis of PTX

1. No lung sliding2. No B lines3. Ideally, a lung point

1. aNo lung sliding

Which side is the PTX?

Tip 1: compare sides

Tip 2: M-mode can help

! Sliding = seashore sign! No sliding = stratosphere sign! But beware ‘false seashore’ with chest

wall movement!

Normal: seashore sign

PTX: stratosphere sign

Stratosphere sign! M-mode = motion mode! If something isn’t moving, it’s a

straight line

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

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.

Lung point sign

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.

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

Sliding or not?

Consolidationa.k.a. the C profile

Alveolar consolidation! If you can see lung tissue, it ain’t normal!! It ain’t aerated

! Collapse ! Consolidation ! Atelectasis ! Contusion! Infarction (PE)

Alveolar consolidation

Putting it all together

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)

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

A, A’, B, B’ or C?

A, A’, B, B’ or C? (NB trick question)

PLAPS: positive or negative?

Normal lungs

• A profile • Up to 2 B lines per window are OK• PLAPS negative

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

Acute cardiogenic pulmonary oedema (APO)

• B profile = • lung rockets in all windows• lung sliding preserved

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

Pulmonary embolus

A profile anteriorly, PLAPS positive or negative i.e. lungs can look normal

Sometimes C profile (pulmonary infarcts)

Asthma / COPD lungs look ‘normal’

• A profile • PLAPS negative

Sticking needles in thorax

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

Let’s wrap this up

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?

Any questions?

3 lung and thorax

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