Hemodynamic

Monitoring

Pressure or Volumes?

Antonio Pesenti

University of Milan

Italy

antonio.pesenti@unimi.it

CCCF 2017

CVP• Is it useful?

• YES:

– It is an important diagnostic element !

Your best guess

• CVP CI HR SBP

• 0-2 2.0 160 70/ ??

• CVP CI HR SBP

• 10 2.0 160 70/ ??

•

Your best guess

• CVP CI HR SBP

• 0-2 2.0 160 70/ ??

• CVP CI HR SBP

• 10 2.0 160 70/ ??

•

Your best guess

• CVP CI HR SBP

• 0-2 2.0 160 70/ ??

• CVP CI HR SBP

• 15 2.0 160 70/ ??

•

Hemodynamic monitoring Tools

• Cardiac function or cardiac output?

• Filling pressures?

• Single measure or trend?

• Accuracy, precision, stability?

Tools

• Echo ( TEE vs TTE)

– CO +-

– Trend+-

– No real pressure

• (Thermo)dilution: reference

– Pressures, continuous

• Doppler output +-

• Pulse contour (calibration)

• Impedance +---

Cecconi et al Intensive Care Med 2015

• 500 ml in 24 min

• Static Marker in 36%

• Dynamic Markers in 22%

• No safety parameter in 72%

What is a Positive fluid

challenge ?• We give the prescribed amount of fluid

and the CO or the SV or the BP increased

more than a certain amount ( 10-15%).

• In my book:

– if no improvement and CVP increases more

than 3 mmHg, then stop

– If improvement and no change in CVP then

may repeat

– If no improvement and no change: think

FLUID RESPONSIVENESS

• Is not a disease

• Normal subjects respond to fluid load by

an increase in CO ( transient)

• Preload Dependence is a normal condition

• Lack of fluid responsiveness is an

abnormal state ( not necessarily

pathological)

Effect of 3 l saline infusion in 3hrsnormal subjects

Kumar Crit Care Med 2004

Fluid responsiveness tests

• Q . Why a test for fluid responsiveness?

• A. To be able to administer fluid safely.

• Q. When is fluid administration safe?

• A. When it does not cause filling pressures

to rise over safety limits.

Am Heart J 1984:107: 404

We assert that the essential function of the rightventricle is not to provide blood flow through thepulmonary but to maintain a low pressure in thehighly compliant systemic venous system.

By maintaining this low central venous pressure , theRV prevents the development of venous distensionand massive peripheral edema

Function of the right ventricle

Keep systemic

venous pressure

low

Function of the Left ventricle

Keep pulmonary

venous pressure

low

Value of filling pressures

Filling pressures tell us how well the heart

works

A better working heart gives the same

output with a lower filling pressure

A worse heart function results in higher

filling pressures for the same output

Filling Pressures

It is true that Frank Starling’s law of the

heart is based upon lenght rather than

pressures

Lenght and volumes are best to study the

heart

Pressures however is what tissues see

The body survives on pressures not

volumes

CVP• CVP is a stopping rule

– Would you give a fluid load to this patient:

• MAP 55 mmHg

• CVP 18 mmHG

• CO 4.5 l/min

• Sat v 65%?

• What if this patient had 20 cm H20 PEEP?

CVP• Would you give a fluid load to this patient:

– MAP 55 mmHg

– CVP 0 to 2,

– CO 4.5 l/min

– Sat 65%

• What if this patient is spontaneously breathing?

CVP• CVP in itself is not a predictor of fluid

responsiveness

• CVP is always a predictor of the risk of

fluid loading and of the price your patient

is going to pay.

CONCLUSION 1

Filling pressures are important global

parameters for adequacy of volemia and

heart function

CONCLUSION 1

Filling pressures are important global

parameters for adequacy of volemia and

heart function

Identical filling pressures may be

associated with very different CO

CONCLUSION 1

Filling pressures are important global

parameters for adequacy of volemia and

heart function

Identical filling pressures may be

associated with very different CO

Identical CO may be associated with

different filling pressures

CONCLUSION 1

Filling pressures are important global

parameters for adequacy of volemia and

heart function

Identical filling pressures may be

associated with very different CO

Identical CO may be associated with

different filling pressures

Filling pressures AND fluid responsiveness

are notthe same thing

CONCLUSION 2 PAOP is critical because it is the major

determinant of EVLW

CONCLUSION 2 PAOP is critical because it is the major

determinant of EVLW

CVP is critical because it is the major

determinant of body organs edema and

dysfunction

CONCLUSION 2 PAOP is critical because it is the major

determinant of EVLW

CVP is critical because it is the major

determinant of body organs edema and

dysfunction

If you want to do a fluid responsiveness

test, best are DRY Fluid challenges:

Mech Ventilation

Leg Raising

Anti shock trousers

Monnet and Teboul Crit Care 2015