7 Putting It All Together – Pre-reading for the FCUS Course

PUTTING IT ALL TOGETHER

SUMMARY

1. (Ongoing resus) Clinical assessment: formulate the question
2. Rapid US screening
3. Answer the question
4. Continue resuscitation
5. Re-scan/ monitor progress/ further investigations

FIRST, FORMULATE THE QUESTION

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.

• Why is the patient arrested / shocked/ breathless?
• Should I give more fluids? (Or inotropes, or vasopressors?)
• Is the ETT in the right place?

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

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.
  • 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
• 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 than 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

SCANNING THE ARRESTED PATIENT

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

• Is there a reversible cause?
• Is the ETT in the right place?

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

• Heart
• Lungs
• Elsewhere (sometimes)

3. Answer the question

4. Continue resuscitation

5. Re-scan / monitor progress / further investigations

ARREST SCREEN: KEY POINTS

• Don’t get in the way of CPR
• Ten seconds for each step: heart-lungs -elsewhere
• Make a working diagnosis
• Re-scan / monitor progress / further investigations

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:

• 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
    • Squashed RV
  • Thromboembolism (PE)
    • DistendedIVC
    • RV squashes LV•
  • Hypovolaemia
    • Flat IVC
    • Small volume heart

• 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

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 5 seconds!

CPR

Pulse check & scan heart

CPR

Pulse check & scan lungs

CPR

Pulse check & consider options

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)

Possible results:

1. Small volume chambers, heart beating
2. Big RV squashing the LV
3. Pericardial fluid
4. Cardiac standstill
5. Inadequate view

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

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.

4. Cardiac standstillUnless clinical assessment suggests reversibility (eg major hypothermia),cease resuscitation.You mayalso ID frankly non-survivable pathologye.g.ID a heart with all four chambers filled with thrombus. (see fig below)

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

STEP 2 OF THE SCREEN: SCAN THE LUNGS

What am I looking for?

• Lung sliding

Why?

• Tension PTX
• Incorrect ETT placement e.g. One lung ventilation
• Oesophageal intubation

Where shall I look?

• Start with the anterior chest. If you don’t see sliding, check the hemidiaphragms as well.

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-lineor 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.
• JB advice:
  • If you can’t differentiate the above conditions, go back to clinical assessment.
    • Is there a reason to suspect PTX? (e.g. chest trauma on that side)
    • Is the ETT a long way down at the teeth? (1-lung intubation)
    • Is the patient an asthmatic? (Mucous plug)
  • If you still can’t figure itout, pick the likeliest possibility and go with it (e.g. drain the possible tension PTX).

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
4. Re-scan / monitor progress / further investigations

THE SHOCKED PATIENT

SUMMARY

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

2.Rapid US screen

• Lungs
• IVC
• Heart

3.Answer the question

• Why is the patient shocked?
• 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:

• Why is the patient shocked?
• Should I give more fluids? (Or inotropes, or vasopressors?)

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, 3rdspacing…)

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
  • Re-scan with every bolus of IV fluid: if still shocked & B profile appears, cease fluids

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

N.B. look for ‘APO mimics’ eg fibrosis, and ‘fluid overload mimics’ e.g. cor pulmonale

BUT WHAT IF THE LUNG AND IVC GIVE CONFLICTING INFORMATION?

e.g. lungs dry & large IVC? Or lungs wet & small IVC?)

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

Go back & reassess the patient, then synthesize your findings (i.e. be a doctor)

WHAT ABOUT LA/LV FIGURE?

Step 1 of the scan: scan the lungs

Where to scan? At least two sites on each side (see figure above)

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:
  • PTX (absent sliding / absent B lines / absent lung pulse / +lung point)
  • Massive effusion (lonely squashed lung fluttering inside large fluid)
  • Pneumonia (Multiple B lines +consolidation)

STEP 2: IVC

DO I REALLY NEED TO SCAN THE IVC?

• A purist would reply ‘Not if Dx already obvious (e.g. 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 (e.g. cor pulmonale) and ‘falsely’ small (e.g. excessive probe pressure)

3 POSSIBLE OUTCOMES:

1. Large IVC, not changing with respiration = elevated CVPMultiple 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)

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 results

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

RESULTS OF STEP 3

STEP 4: STOP & THINK

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

• What causes have I excluded?
• What else is left?
• Can bedside US help any further?
  • Abdomen (hypovolaemia: AAA / free fluid)
  • 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 or both of:
  • 2 or 3-point compression DVT scan (is it a PE?)
  • Abdomen (is it AAA? Free fluid?)

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 and the IVC
• If lungs still dry/IVC flat, you can give more IV fluid. Once wet lungs appear / IVC full or patient improves, cease fluids

BUT WHAT ABOUT OTHER TREATMENT?

• Inotropes / pressors
• IV antibiotics
• Etc

That’s a doctor question.

If/when you decide your patient needs them, give them.

SUMMARY: THE SHOCKED PATIENT

1. Anterior lung fields (this time 2 points)
2. IVC
3. Single view heart
4. Take a step back & consider:
   1. Leg veins (obstructive: PE)
   2. Abdo (hypovol: AAA / free fluid)
   3. Other tests

SUMMARY: THE BREATHLESS PATIENT

1. (Ongoing resus) Clinical assessment: formulate the question: why is the patient breathless?
2. Rapid US screen
   1. Lungs
   2. IVC
   3. Heart
   4. 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

STEP1: SCAN THE LUNGS

Where shall I look?

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)
4. 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?

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 completely collapsed

Acute pulmonary oedema

• B-profile
  • Plenty of B-lines in all windows
  • Lung sliding is preserved
  • Often see effusions

Pneumonia or ARDS

• Lungs might look wet
  • Lung rockets in all windows
  • Lung sliding reduced or absent
  • Pleural line may be irregular
• Lungs might look patchy (wet/dry areas)
• Lungs might look chunky

Pulmonary embolus

• Lungs usually look dry
• Sometimes you can see chunks

Asthma/ COPD

• Lungs usually look dry

STEP 2: SCAN THE IVC

See the previous sections for how to scan and 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.

STEP 3: SCAN THE HEART

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

Why even bother?

• Well, just like the IVC:
  • 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.
  • This step is also prone to false positives and negatives
  • This step is skipped altogether in the BLUE protocol.
• But once again, most of us would scan the heart, to look for dual pathology.

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 2-3sites 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

SUMMARY: SCANNING THE BREATHLESS PATIENT

• Step 1: the lungs
• Step 2: the IVC
• Step 3: the heart
• Step 4: the veins

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 doctor 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.