critical care ultrasound course dr justin bowra …...the san critical care ultrasound manual justin...

THE SAN CRITICAL CARE ULTRASOUND MANUAL

JUSTIN BOWRA 1

Critical Care Ultrasound Course

Dr Justin Bowra CCUS Manual 7:

Putting it all together:

SCANNING THE CRITICALLY ILL PATIENT

Adapted from the RUSH protocol, and Lichtenstein's BLUE, FALLS & SESAME protocols


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A WORD OF WARNING FROM JB CCUS is most useful in the sickest patients, because the US features of the

responsible diseases are more obvious.

In fact, these US techniques have only been ‘road tested’ in the critically ill, and NOT those with mild degrees of illness, so its accuracy is unknown in

mild illness.

Put it another way: CCUS will pick up cardiogenic pulmonary oedema or a massive PE, but not mild CCF or a small PE.


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Summary

1. (Ongoing resus) Clinical assessment: formulate the question

2. Rapid US screen

3. Answer the question

4. Continue resuscitation

5. Re-scan / monitor progress / further investigations

First, formulate the question For clinicians, performing the clinical assessment comes before performing the US. In the critically ill patient, US can assist with a number of questions, according to the context, e.g:

a. Why is the patient arrested / shocked / breathless?

b. Should I give more fluids? (Or inotropes, or vasopressors?)

c. Is the ETT in the right place?

The CCUS screen won’t tell you the diagnosis every time, but it will usually help.


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How to perform a rapid US screen in the critically ill patient

Which probe?

As this is a rapid screen (not a formal echocardiogram), and it’s only looking for the bloody obvious, you can use either:

• The abdominal (curved) probe

• The cardiac (sector) probe

Which preset?

Once again, it’s not that important. You can get away with either:

• abdominal preset

• cardiac preset

Where to start my scan?

• Overall principle: it depends on the clinical context. Some people prefer to start with the heart, others with the IVC.

• The arrested patient: start with the heart.

• The breathless patient: start with the lungs.

• The shocked patient: this can be a tricky one.

o If the clinical picture points to a cause, start there E.G:

§ You suspect tamponade: start with the heart.

§ You suspect pneumothorax: start with the lungs.

o In truly undifferentiated shock: it’s up to you. I prefer to start with the lungs, then the IVC. That’s because:

§ Lungs/IVC are easier to scan then the heart

§ Lungs/IVC are faster to scan then the heart

§ Lungs/IVC provide more direct info

§ E.G. Wet lungs + ‘normal’ TTE = likely still to be CCF


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Most importantly…

If the lungs are dry, your team can keep bolusing IV fluid while you keep scanning.


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The arrested patient


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Summary: scanning the arrested patient

1. (Ongoing resus) Clinical assessment: formulate the questions a. Is there a reversible cause? b. Is the ETT in the right place?

2. Rapid US screen (don’t get in the way of CPR)

a. Heart

b. Lungs

c. Elsewhere (sometimes)

3. Answer the question

4. Continue resuscitation


Arrest screen: key points

1. Don’t get in the way of CPR

2. Ten seconds for each step: heart – lungs - elsewhere

3. Make a working diagnosis


1. Formulate the question

Whenever using any test to assist diagnosis and treatment, remember you are a clinician first. Think: why do I need to use US? In the case of the arrested patient, US can assist with the following two questions:

a. Why is the patient arrested: is there a reversible cause?

US can help ID the following causes:

• Tension PTX: one lung shows:

◦ Absent lung sliding

◦ Absent B lines

◦ NB remember that 1-lung intubation has a similar US picture, see below.

• Tamponade:

◦ Pericardial fluid

◦ Distended IVC


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◦ Squashed RV

• Thrombolembolism (PE)

◦ Distended IVC

◦ RV squashes LV

• Hypovolaemia

◦ Flat IVC

◦ Small volume heart

b. Have I successfully intubated? Occasionally it can be difficult to confirm ETT placement (eg if unable to obtain an ETCO2 trace). By demonstrating bilateral pleural sliding, chest US can rapidly demonstrate that the ETT is correctly placed.


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2. How to perform a rapid US screen in the arrested patient

Caution: don't get in the way of CPR!

You need to scan during the pulse check

You have ten seconds!

CPR

Pulse check & scan heart

CPR

Pulse check & scan lungs

CPR

Pulse check & consider options


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Step 1 of the US screen: single view of the heart

• Window: any can be used, but the subcostal is most likely to be successful if you use the curved probe.

• Probe transverse and angled towards the head (cephalad)


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Possible results:

1. Small volume chambers, heart beating

2. Big RV squashing the LV

3. Pericardial fluid

4. Cardiac standstill

5. Inadequate view


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1. Small volume chambers, actively beating heart

This is pseudo-EMD. You still have a chance!

Action:

• Ongoing resuscitation with IV fluids

• While seeking the cause

2. Big RV squashing the LV

A distended, high pressure RV squashing LV is most likely a PE in the context of cardiac arrest.

Caveats:

• Is it chronic? Thickened RV wall

Action:

• consider thrombolysis

• If in doubt, consider 3-point DVT scan


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Arrested patient, high pressure RV compressing LV. Massive PE. Parasternal long axis view.


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3. Pericardial fluid In the context of the arrested patient, a substantial pericardial effusion suggests a tamponade. Caveat:

• It might be an incidental finding, esp likely if small volume • Aortic dissection: needs OT • Penetrating chest trauma: needs ED thoracotomy.

Action: immediate pericardiocentesis.


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Substantial pericardial fluid compressing RV. Pericardial tamponade. Subcostal short axis view.


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4. Cardiac standstill

Unless clinical assessment suggests reversibility (eg major hypothermia), cease resuscitation. You may also ID frankly non-survivable pathology e.g. ID a heart with all four chambers filled with thrombus. (see fig below)


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Arrested patient, chambers filled with thrombus, cardiac standstill. Parasternal short axis view.

5. Inadequate view

If you can't obtain an adequate view, available options:

◦ Try a different window

◦ Try the cardiac probe on the cardiac preset

◦ Get help!

◦ Turn off the machine.


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Step 1: single view heart

Big RV

Pericardial fluid

Cardiac standstill

Inadequate view

Pseudo-EMD

PE

Consider

thrombo-lysis

Tamponade

Drainage

Hypovolaemia

IV fluid Proceed to step 3

R.I.P.

Exclude other reversible

causes Cease CPR

Keep looking Get help


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Step 2 of the screen: scan the lungs

What am I looking for? Lung sliding.

Why?

• Tension PTX

• Incorrect ETT placement eg

o One lung ventilation

o Oesophageal intubation

Where shall I look? Start with the anterior chest. If you don’t see sliding, check the hemidiaphragms as well.


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TOP TIP: you don’t need to be exact

•  If tension PTX, it will fill the hemithorax •  You’ll see it anywhere on the anterior chest

Step 2 findings

Neither lung is sliding?

One lung is not sliding?

Both lungs ventilating

PTX or

1 lung ventilation

Not ventilating!

No PTX

Check the airway

Check the ETT Is there a lung Point (PTO)?

Go to step 3


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TRAPS: Pneumothorax (PTX) or 1-lung intubation?

This can be very tricky to differentiate in the arrested patient.

• In both conditions, lung sliding is absent.

• In 1-lung intubation, you might be lucky and see a B-line or two.

• In PTX, the lung pulse is absent. In 1-lung intubation, the lung pulse is present in patients with a pulse. But in the arrested patient, lung pulse will also be absent (or very weakly present in PEA).

• In a small PTX, there will be a lung point: if you’re in a hurry, this just means that sliding is absent at the anterior chest (= highest point) and present at the diaphragm (=lowest point). But in a tension PTX, the entire lung is collapsed and there will be no lung pulse.

Other mimics

• A large mucous plug may block one bronchus, mimicking a 1-lung intubation.

My advice

• If you can’t differentiate the above conditions, go back to clinical assessment.

o Is there a reason to suspect PTX? (e.g. chest trauma on that side)

o Is the ETT a long way down at the teeth? (1-lung intubation)

o Is the patient an asthmatic? (Mucous plug)

• If you still can’t figure it out, pick the likeliest possibility and go with it (e.g. drain the possible tension PTX).


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Step 3 of the scan: scanning elsewhere (seldom required)

What am I looking for? Cause of hypovolaemia.

Why?

• Patient is in PEA: heart is beating but no output

• Chambers are small volume.

What am I looking for? Cause of hypovolaemia.

Where shall I look?

• The abdomen: free fluid and AAA.

Arrest screen: summary

1. Don’t get in the way of CPR

2. Ten seconds for each step: heart – lungs - elsewhere

3. Make a working diagnosis



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The shocked patient


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Summary

1. (Ongoing resus) Clinical assessment: formulate the question 2. Rapid US screen

a. Lungs b. IVC c. Heart

3. Answer the question a. Why is the patient shocked?

b. Should I give more fluids? (Or inotropes, or vasopressors?) 4. Continue resuscitation 5. Re-scan / monitor progress / further investigations

First, formulate the question

In the shocked patient, US can assist with the following two questions:

a. Why is the patient shocked?

b. Should I give more fluids? (Or inotropes, or vasopressors?)

The shock screen won’t tell you the diagnosis every time, but it will tell you when it’s safe to give IV fluids (dry lungs & small IVC)… or when to stop (wet lungs, large IVC).

a. Why is the patient shocked?

If you (& the patient) are lucky, the rapid shock screen might reveal one of the following causes:

• Obstructive (TPTX, massive PE, tamponade)

• Cardiogenic (wet lungs)

• Hypovolaemic (fluid loss, 3rd spacing…)

b. Should I give more fluids?

• Are the lungs wet or dry?

• Is the IVC full or empty?

If US demonstrates dry lungs and a small IVC, give fluids (but re-scan with every bag of IV fluid: if still shocked & B profile appears, cease fluids).


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If US demonstrates wet lungs and distended IVC, the answer is ‘no more fluids’ and you should reach for inotropes / pressors etc.

(NB look for ‘APO mimics’ eg fibrosis, and ‘fluid overload mimics’ eg cor pulmonale)

BUT what if the lung and IVC give conflicting information? (eg lungs dry & large IVC?) (or lungs wet & small IVC?)

This isn’t common, but recall that each sign has false positives & negatives (eg IVC distended due to chronic cor pulmonale).

Go back & reassess the paeient, then synthesize your findings.

=Be a doctor.

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What about large LA/LV? Surely that suggests I should avoid IVT?

A. Not in isolation.

Even patients with dilated cardiomyopathy can suffer hypovolaemic shock.

But be sensible & consider smaller boluses,

and correlate with other findings.


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Step 1 of the scan: scan the lungs

Where to scan?

At least two sites on each side (see figure below).

What am I looking for?

• Bilateral dry lungs: safe to give fluids (=fluid tolerant). Might not be fluid responsive, so move to step 2 (IVC).

• Bilateral wet lungs (> 3 B lines in all lung fields) = fluid intolerant = most likely cardiogenic pulmonary oedema. Could still be bilateral widespread inflammatory oedema (e.g. ARDS & severe pneumonia). Once again, time for step 2 (IVC).

• Unilateral pathology:

o PTX (absent sliding / absent B lines / absent lung pulse / + lung point)

o Massive effusion (lonely squashed lung fluttering inside large fluid)

o Pneumonia (Multiple B lines + consolidation)


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Step 1 findings

One lung not sliding

Both lungs slidng

A profile: Continue

IVT

B profile: Pulmonary

Oedema Treat.

A/B or C profile:

Pneumonia Continue

IVT Treat cause.

A’ profile: PTX?

Look for lung point, consider DDX. Treat

B’ profile: Pneumonia

Treat.

Step 2


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Step 2: IVC

Do I really need to scan the IVC?

• A purist would reply ‘Not if Dx already obvious (eg pneumonia).’

• However, most of us would look, to get a feel for fluid responsiveness.

Beware false positives & negatives!

• But remember that IVC can be ‘falsely’ large (eg cor pulmonale) and ‘falsely’ small (eg XS probe pressure)

3 possible outcomes:

1. Large IVC, not changing with respiration = elevated CVP

Multiple causes…but probably not fluid responsive

Actions:

• Reassess clinical picture

• Consider other tests

• Avoid indiscriminate IVT

2. Flat IVC & collapsing = fluid responsive

Actions:

• Give IVT

• Proceed to step 4

3. Inadequate view, or somewhere between the 2 extremes: IVC window is probably not helpful

Possible actions:

• Try scanning the other veins instead eg IJV (caution with probe pressure). If the IVC is ‘the poor man’s CVP’, then the IJV is ‘the poor man’s IVC.’

• Or get help

• Or proceed to step 3 (the heart)


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The IVC is most useful at extremes In breathless patients at 45 degrees (semirecumbent):

IVCCI <15% suggests patient is wet (eg CCF)

In the supine, spontaneously breathing, shocked patient:

IVCD <0.9cm suggests patient is dry

IVCCI > 50% suggests patient is dry IVCCI <50% suggests patient is wet

In ventilated supine patients:

An IVCCI >2.5cm suggests patient is full. An IVCD <1.2cm suggests RAP <10mmHg

But all this comes from small studies with conflicting reults.

So: dry lungs, & IVC shows…

Anything else Small IVC, not collapsing

Large IVC, collapsing

Inadequate view

Large IVC <50% collapse

Avoid IV fluids Proceed to step 3

Give IV fluids Get help or cut your losses

Proceed to step 3


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Step 3: single view of the heart

• For details (window, possible results): see Arrest algorithm

But surely I need all 4 cardiac windows?

Not for this scan.

You’re in a rush. It’s a screening test, looking for bloody obvious

pathology in a critically ill patient. For more subtle pathology, yes you will need plenty

of windows.


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Controversy If step 1 & 2 have already demonstrated a diagnosis (tension PTX,

pneumonia, APO) some consider it unnecessary to scan the heart, while others (including me) prefer to ‘make sure’ by including the heart.

After all, there may be dual pathology.

And there’s another thing:

LV failure commonly appears as spuriously 'normal' LV on basic 2D echo. So if wet lungs/big IVC but

heart looks OK, start treating for APO, then proceed to focused TTE & reassess patient.


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Results of step 3:

Step 3: single view heart

Big RV Big IVC

Pericardial fluid Big IVC

Inadequate view

Small / normal heart Collapsing IVC

PE (probably)

Consider thrombolysis

Tamponade (probably)

Drainage / fix dissection

Hypovolaemia/ sepsis

IV fluid Consider aorta/

EFAST

Try another window Try cardiac probe

Get help

!#?!!


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Step 4: stop & think

Take a step back & have another look at the patient & other information.

• What causes have I excluded?

• What else is left?

• Can bedside US help any further?

o Abdomen (hypovolaemia: AAA / free fluid)

o Leg veins (obstructive: PE)

Who needs step 4?

Anyone with:

Dry lungs with sliding, flat IVC, diagnosis still unclear, and…

***shock unresponsive to fluids***

• Is it sepsis?

• Is it a ruptured AAA?

• Is it PE? (unlikely in my view, but you never know)

Options: either/ both of:

• 2 or 3-point compression DVT scan (is it a PE?)

• Abdomen (is it AAA? Free fluid?)


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Step 4: dry lungs / flat IVC / heart OK, or inadequate views, & shock still unresponsive

to IV fluids Scan the abdomen

DVT seen = probably PE

Scan for DVT

Still haven’t found anything?

Now what? PTO

Free fluid AAA

Aortic dissection

Compression US leg veins

EITHER / BOTH


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Now what?

You’ve reached the end of the scan.

If patient still shocked and fluids didn’t work, you’ve ruled out cardiogenic, PTX, tamponade…

…but not PE.

If it’s still on your list, you need a different test.

But while arranging other tests,

Keep treating the patient (e.g. pressors / fluids)

Keep scanning the lungs & IVC.

If lungs still dry/ IVC flat, you can give more IV fluid.

Once wet lungs appear / IVC full or patient improves, cease fluids.


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But what about other Px?

Inotropes / pressors IV antibiotics

Etc

That’s a doctor question. If/when you decide your patient needs them, give

them.

75

Top tip

Remember to be a doctor. Bedside US is there to assist your clinical

judgement, not replace it.


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Summary: the shocked patient

1. Anterior lung fields (this time 2 points)

2. IVC

3. Single view heart

4. Take a step back & consider:

• Leg veins (obstructive: PE)

• Abdo (hypovol: AAA / free fluid)

• Other tests

The shock screen won’t tell you the diagnosis every time, but it will tell you when it’s safe to give IV fluids (dry lungs & small IVC)… or when to stop (wet lungs, large IVC).


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The breathless patient


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Summary

1. (Ongoing resus) Clinical assessment: formulate the question: why is the patient breathless?

2. Rapid US screen a. Lungs b. IVC c. Heart d. A new step: Veins for DVT

3. Answer the question 4. Continue resuscitation 5. Re-scan / monitor progress / further investigations

First, formulate the question

In the shocked patient, US can assist with the question:

Why is the patient breathless?

In the severely breathless patient, US can reach a diagnosis in approximately 90% of cases.

A four-step scan

1. The lungs: this time 3 or 4 points on each side

2. IVC as before

3. Heart as before

4. Veins for DVT


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Step 1: scan the lungs

Where shall I look? (See CCUS 2: LUNG for details.)

3 or 4 points on each side this time, to get a better look at the lung:

1. The upper anterior chest

2. The lower anterior chest

3. The posterolateral chest (the ‘Morison’s Pouch of the Chest’, a.k.a. Lichtenstein’s PLAPS point)

Note: even this is just a screening test.

When you’ve finished stabilizing the patient, scan as much of the lung as possible, especially the back of the chest.

Q: What am I looking for? (See CCUS 2: Lung for details)

Normal lungs Dry(-ish) air

Scatter, often with A-lines Up to 2 B lines per window are OK No chunkiness No pleural fluid

Pneumothorax Very dry air Usually see A-lines No sliding No B lines No lung pulse See a lung point unless lung is completely collapsed

APO B profile = Plenty of B lines in all windows Lung sliding preserved Often see effusions

ARDS or pneumonia Lungs might look wet • lung rockets in all windows • lung sliding reduced / absent • And pleural line may be irregular

Lungs might look patchy (wet / dry areas) Lungs might look chunky


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Pulmonary Embolus Lungs usually look dry.

Sometimes you see chunks.

Asthma/ COPD Lungs usually look dry.


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Step 2: scan the IVC

See the previous sections for how to scan & interpret images.

Why even bother?

Well, to be fair you probably don’t need to if the diagnosis is obvious. This step is probably only useful if the lungs ‘appeared normal’ and you’re looking for PE.

And there’s another problem: false positives & negatives.

• If the patient has very high intrathoracic pressures from severe asthma/COPD, or chronic cor pulmonale, the IVC will be distended anyway… i.e. not every big IVC is due to a massive PE.

• If the IVC is small, could the patient still have a PE? Of course. A submassive PE will make someone very breathless if they have little inspiratory reserve.

This is why Lichtenstein’s BLUE Protocol skips the IVC and heart and goes straight to the veins to look for a DVT.

Until a more definite answer is reached on this issue, probably each clinician needs to make up his/her mind on this step.


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Step 3: scan the heart

See the previous sections for how to scan & interpret images.

Why even bother?

Well, just like the IVC:

1. You probably don’t need to if the diagnosis is obvious. This step is probably only useful if the lungs ‘appeared normal’ and you’re looking for PE.

2. This step is also prone to false positives and negatives

3. This step is skipped altogether in the BLUE protocol.

But once again, most of us would scan the heart, to look for dual pathology.


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Step 4 (or step 2 if using the BLUE protocol): scan the veins

Can I skip this step?

Well, sometimes: especially if you’ve found a cause for the breathlessness and you’re in a hurry. But if the patient’s not improving and you’re looking for dual pathology,

then it’s worth including this step.

What am I looking for?

A deep venous thrombosis (DVT).

Why?

If you see a DVT in an acutely SOB patient and no other obvious cause for their symptoms, then you may as well assume there’s a PE.

Is that always true?

No. But if you are considering thrombolysis, it’s always comforting to see a DVT.

Where and how shall I look? This course does not strictly cover DVT scanning. See CCUS Appendix: a quick guide to DVT compression US for details eg ‘5 sites to consider compressing’.

You may choose to scan as many or as few of the following sites as you consider appropriate (although most of us only scan 2-3 sites on each leg):

• Upper femoral vein (at or around the femoral confluence in the groin) • Lower femoral vein (just above and medial to the knee) • Popliteal fossa (behind the knee) • Below the knee • Upper limbs: IJV, subclavian vein

NB: this is rule-in, not rule-out. Even if you scan all the above sites and attain the published expert sensitivity of 81%,

you’ll still miss 19% of patients with PE.


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Summary: scanning the breathless patient

Step 1: the lungs

Step 2: the IVC

Step 3: the heart

Step 4: the veins


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Outstanding issues

1. Does RV/IVC distension occur in status asthmaticus / severe COPD? If so, this could limit its use as a discriminator for massive PE (and is the reason Lichtenstein does not include it on the BLUE protocol)

BUT realistically we assume that a sensible dr can pick asthma/COPD clinically, so this should not be an issue.

2. Scanning for DVT

• Include upper limb? Only adds 4% sensitivity

• Include below knee? This will be controversial for many

• Details less important than the understanding that this is ‘rule-in’, not ‘rule-out’

3. Should we include heart / IVC or not?

4. Finally, validation studies are needed: by non-experts, in the setting of all breathless patients in the ED.

critical care ultrasound course dr justin bowra …...the san critical care ultrasound manual justin...

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