11 shock algorithm

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The shocked patient

Adapted from Lichtenstein's BLUE points & FALLS protocol

(with permission)

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Summary

1 (Ongoing resus) Clinical assessment: formulate the question

2 Rapid shock screen3 Form a working diagnosis4 Continue resuscitation 5 Re-scan / monitor progress / further

investigations

1. Formulate the question

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1. Formulate the question

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

b. Why is the patient shocked?

The shock screen won’t tell you the diagnosis every time, but it will tell you when not to give IV fluids… or when to stop (B profile

appears)

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Why is the patient shocked?

• Obstructive (TPTX, massive PE, tamponade)

• Cardiogenic• Hypovolaemic (fluid loss, 3rd spacing…)• Distributive (septic, anaphylactic,

neurogenic)• Dissociative (CO, cyanide)

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Why is the patient shocked?

• Obstructive (TPTX, massive PE, tamponade)

• Cardiogenic (lung rockets)• Hypovolaemic (fluid loss, 3rd spacing…)• Distributive (septic, anaphylactic,

neurogenic)• Dissociative (CO, cyanide)

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Should I give more fluids?

• Lungs: wet or dry?• IVC: collapsing or distended?

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Should I give more fluids?

Wet lungsDistended IVC… probably not

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

eg cor pulmonale)

Dry lungsSmall IVC

…yes (but re-scan with every bag of IV fluid: if still shocked & B profile appears, cease fluids)

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What if lungs dry & large IVC?(or lungs wet & small IVC?)

A. Each sign has false positives & negatives.

Go back & reassess the patient, 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.

2. The shock screen

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Curved probe, abdominal preset

• Machine settings: as for arrest screen

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A 3-step scan (plus 1)

1. Anterior lung fields (this time 2 points)2. Single view heart3. IVC (hypovolaemia / obstructive shock)4. Take a step back & consider:

• Leg veins (obstructive: PE)• Abdo (hypovol: AAA / free fluid)• Other tests

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The shock scan

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The shock scan

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Step 1: anterior chest: upper & lower BLUE points

• Probe sagittal, midclavicular line• 2 spots on each side• i.e. upper chest & lower chest

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Recall: upper & lower BLUE points

1 1

2 2

Step 1 findings

One lung not sliding

Both lungs slidng

A’ profile B’ profile A profile B profile A/B or C profile

Recall: A lines versus B lines

A lines B lines

Recall: A lines versus B lines

A linesHorizontal artefactsOnly air is presentPresent in dry lungsPresent in PTX

B linesVertical artefactsAir/fluid mix in lungNot seen in PTXEven 1 B line rules

out PTX at that site

A vs A’ profile: is sliding present?

A vs A’ profile: is sliding present?

A vs A’ profile: is sliding present?

A or A’ profile?

A or A’ profile?

A & A’ profile

A lines (or no lines) in all 4 lung windows+

Pleural sliding present = A profile = dry lungsPleural sliding absent = A’ profile = PTX /

1 lung ventilation / other

B & B’ profile:Multiple B lines = wet lungs

Multiple B lines = pulmonary oedemaAPO = cardiogenic oedema

ARDS = non cardiogenic oedemaPneumonia = local oedema

Note the difference w.r.t. pleural sliding

ARDS/ disseminated pneumonia:Exudate

Proteinaceous‘sticky’

Reduced / absent lung sliding, irregular

pleural lineB’ profile

APO:Transudate

Lung sliding is preserved, smooth

pleural lineB profile

B or B’ profile?

B or B’ profile?

B or B’ profile?

B & B’ profile

At least 3 B lines in all 4 anterior windows= wet lungs

Pleural sliding present = B profile = APO

Pleural sliding reduced /absent, irregular pleural line = B’ profile = disseminated pneumonia / ARDS

Is that 100% true?

No, but it’s close.B profile + preserved lung sliding = almost

always APO.B profile + absent sliding = almost always

pneumonia.

NB remember the 90% rule

Recall: A/B profile

The windows show a mix of A & B=

Patchy wet lung(s) (usu pneumonia)

Recall: C profile

Recall: C profile

The windows show anterior consolidation=

PneumoniaARDS

(rarely: PE)

Small amounts of consolidation = ‘irregular pleural line’

Step 1 findings

One lung not sliding

Both lungs sliding

A’ profile B’ profile A profile B profile A/B or C profile

Step 1 findings

One lung not sliding

Both lungs sliding

A profile:Continue

IVT

B profile:Pulmonary

OedemaTreat.

A/B or C profile:

PneumoniaContinue

IVTTreat cause.

A’ profile:PTX?

Look for lung point,consider DDX. Treat

B’ profile:Pneumonia

Treat.

Step 2

Step 2 (after PTX ruled out)

Single view of heart

Wait a minute!

Do I need to scan the heart if I already have a diagnosis from the lung scan (PTX,

pneumonia, APO)?

Controversial

Most of us would still scan heart to be sure.Some wouldn’t.

(See APO note next slide)

This step only yields useful information if it demonstrates obvious pathology: ie ‘rule in, not rule out’.

If negative, you will need to proceed to step 3.

Step 2 (if lung sliding & B profile)

This is usually acute cardiogenic pulmonary oedema (APO). Occasionally severe bilateral

pneumonia / ARDS can look like this.

Fibrosis can look like this, but is usually limited to upper or lower lobes.

If you saw B profile on step 1…… and step 2 shows poor

LV function= acute cardiogenic

pulmonary oedema(APO)

And step 2 shows ‘normal’ LVStill probably APO- start

treating(but re-check clinical picture

to be sure it's not severe bilateral pneumonia /

ARDS)

LV failure commonly appears as spuriously 'normal' LV on basic 2D echo. So if B profile but heart looks OK, start

treating for APO, then proceed to focused TTE & reassess patient.

Back to the heart.What am I looking for?

Tamponade?Massive PE?

Hypovolaemia?

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Step 2: single view heart

• Using the curved probe, subcostal view is easiest• Probe transverse, marker to patient's right• ID heart (probe angled cephalad)• Options if you can't obtain an adequate view:

• Try different window (apical, parasternal)• Try different probe (phased array)• Get help

Subcostal scan heart

Step 2: single view heart (& dry lungs)

Big RVSquashing LV

Pericardial fluid Inadequate view

Small volume heart

Heart grossly NAD

?

Step 2: single view heart (& dry lungs)

Big RVSquashing LV

Pericardial fluid

Inadequate view

Small chambers or heart grossly

normal

PE (probably)

Consider

thrombolysis

Tamponade (probably)

Drainage

Hypovolaemia/ sepsis?Could still be PE!

IV fluidProceed to step 3

Try another windowTry cardiac probe

Get help

Step 3

IVC

Hang on!

Do I need to scan the IVC if I already have a diagnosis from steps 1 & 2?

(PTX, massive PE, tamponade, pneumonia, APO)

Controversial

Not if Dx already obvious (eg tamponade).Yes if Dx still unclear: dry lungs, small volume

heart (e.g. you haven’t ruled out PE yet)But remember that IVC can be ‘falsely’ large

(eg cor pulmonale) and ‘falsely’ small (eg XS probe pressure)

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So proceed to step 3...

...if lungs are dry & no obvious PE or tamponade

But be a doctor & synthesize the findings.

Step 3: dry lungs, small vol heart, IVC

Anything elseSmall IVC

Large IVC & collapsing

Inadequate view

Large IVC<50% collapse

?

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IVC 1

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IVC 1

50

IVC 2

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IVC 3 (transverse)

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IVC 3 (transverse)

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Large IVC (>2.3cm), <50% collapse

= elevated CVPMultiple causes

…but probably not fluid responsive

Actions:Reassess clinical picture

Consider other testsAvoid indiscriminate IVT

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Anything else

Small IVC <1.5cmCollapsing IVC >50%

= fluid responsive

Actions:Give IVT

Proceed to step 4

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Inadequate view

Reconsider whether you really need the IVC information

Actions:Either get help

Or proceed to step 4

So: dry lungs, small vol heart, IVC…

Anything elseSmall IVC, not collapsing

Large IVC, collapsing

Inadequate view

Large IVC<50% collapse

Caution with fluidsProceed to step 4

Give fluidsProceed to step 4

Get help or cut your losses

Proceed to step 4

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Step 4

• Take a step back• Have a think (& another look at the patient &

other information)• What causes have I excluded?• What else is left?• Can bedside US help any further?

• Abdomen (hypovol: AAA / free fluid)• Leg veins (obstructive: PE)

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Who needs step 4?

Anyone with:Dry lungs, lung sliding present, diagnosis still

unclear, and…***shock unresponsive to fluids***

Is it sepsis?Is it a ruptured AAA?

Is it PE?

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Step 4

Options: either/ both of:3-point compression DVT scan (is it a PE?)

Abdomen (is it AAA? Free fluid?)

Step 4: dry lungs, diagnosis unclear, shock unresponsive to IV fluids

DVT not seen:Scan the abdomen

DVT seen= PE

3-point compression leg veins

Normal aortaAAA ruled out

Now what?PTO

AAA seen =Ruptured AAA

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Now what?

You’ve reached the end of the scanPatient still shockedFluids 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.

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But while arranging other tests…

Keep scanning the lungs

If lungs still dry, you can give more IV fluid

Once B profile appears or patient improves, cease fluids

Recap: the shock scan

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A 3-step scan (plus 1)

1. Anterior lung fields (this time 2 points)2. Single view heart3. IVC (hypovolaemia / obstructive shock)4. Take a step back & consider:

• Leg veins (obstructive: PE)• Abdo (hypovol: AAA / free fluid)• Other tests

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The shock scan

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The shock scan

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Further tests?

After resuscitation phaseIf shock screen didn't sufficeIf clinical picture demands it

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Summary

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).