Fluid challenge Revisited
D. Matamis M.D
I.C.U PAPAGEORGIOU Hospital
Thessaloniki Greece
Physiology
DO2 – VO2 - SvO2
Determinants of Tissue Oxygenation
Relationship between Ht and DO2
VO2-VCO2 production during shivering
VO2-VCO2 production during agitation
VO2-DO2 dependence
Tissue Hypoxia
DO2/VO2 imbalance
O2 reserves
Decrease in O2 delivery
25% of the Ο2 delivered in the
periphery is used
DO2=CO x CaO2 x 10
-
Increase in O2 Consumption
Is it reasonable?
- CaO2 =20 ml/dl
- (a-v)DO2 = 5 ml/dl
- SvO2 75%,
VO2= CO x (a-v)DO2
Marathon Runners
Deep Divers (mammals, Birds)
Tissue Hypoxia -The Concept of
Supra-normal Values

Critically ill patients are suffering
– Trauma
– Severe Sepsis
– Extensive Surgery

Goals of the hemodynamic optimization
–
DO2 ?
–
SvO2 ?,
–
C.O ?
If we increase DO2
Mortality
SvcO2 ?
Regional SvO2
–
–
–
–
–
–
SvcO2
jugular SvO2
hepatic SvO2
renal SvO2
coronary sinus SvO2
mesenteric SvO2
SvO2 or SvcO2 ?
SvO2 or SvcO2 ?
PRO
CON

Fluids are primarily required to reverse hypovolemia

Hypovolemia may be due to external or internal fluid losses
 External fluid losses (Bleeding, losses from G.I, U.T (diabetes, diabetes
insipidus), skin or peritoneal surface)
 Internal fluid losses (exudation, transudation or redistribution of the
body fluids – distributive shock, especially in sepsis)

Volume replacement is essential to restore C.O and perfusion to vital organs
and tissues
Misconceptions about fluid administration

We should stop fluid administration because the CVP is high

We should stop fluid administration because there is evidence of lung edema
on the chest X ray

We should stop fluid administration because the patient has already received
a large volume in a short period of time

Tachycardia is mainly due to volume deficit and we should prompt increase
the fluid administration

I gave fluids to increase the CVP to 12 mmHg to exclude an underlying
hypovolemia
Clinical end points of fluid challenge
To increase SV and C.O
 To increase ABP
 To increase urine output


When the decision of fluid loading is based on clinical criteria
and /or CVP measurements, 50% of the patients do not respond
by a significant increase in SV and CO
Methods of preload assessment
Static indices
CVP
 PAOP

Dynamic indices
Pulse Pressure Variation (PPV), or Stroke Volume
Variation (SVV)
 Aortic blood flow velocity
 IVC collapsibility
 Passive Leg Rising (PLR)
 2D ECHO of the heart chambers

CVP-PAOP
CVP (Pressure) reflect the preload of the RV=RV Volume

Limitations



RV compliance
Ventricular inter-dependence
Lung hyperinflation – PVR
PAOP (Pressure) = LA pressure=LVED Pressure = LVED Volume

Limitations



LV Compliance
Tachycardia, MV disease,
Lung Hyperinflation (High PEEP, auto PEEP)
Static indices CVP-PAOP
Static indices CVP-PAOP
Static indices CVP-PAOP
Am J Respir Crit Care Med 2000. 162:134-138
PPmax
PPmean
PPV =
PPmax – PPmin
PPmean
The pulse pressure variation is the variation in pulse pressure over the ventilatory cycle,
measured over the previous 30 second period.
Dynamic indices - PPV
Dynamic indices - Aortic Blood Velocity
Chest 2001.119:867
Dynamic indices - SVV
Dynamic parameters of volume responsiveness – Stroke Volume Variation
SVmax
SVmin
SVmean
SVV =
SVmax – SVmin
SVmean
Dynamic indices - SVV
Dynamic indices - SVV

Stroke volume
SV increases during inspiration
SV decreases during inspiration
Dynamic indices - SVV
Many studies have shown that SVV is a very accurate predictor of fluid
responsiveness
SVV > 15% a positive response to fluid loading is very likely
SVV< 10% a positive response to fluid loading is very unlikely
Using SVV to predict fluid responsiveness
Limitations of the SVV
- Sustained cardiac arrhythmia
- In Spontaneous Breathing patients (false negative)
- In ARDS patients ventilated with small Vt (<8ml/kg)(false negative)
- RV failure (false positive)
- Drugs ( Esmolol)
In cases of false negative SVV
is there an alternative solution?
- When giving fluids is not risky (Surgery patients)
– Give fluids and monitor SV and CO


If SV and CO up Responder
If SV and CO stable
Inotropes
- When giving fluids is risky (ARDS patients)
- PLR maneuver for 1-2 minutes
Passive leg raising and fluid responsiveness
Crit Care Med 2006;34:1402
Positive response
Negative response
Passive Leg Raising - PLR
IVC collapsibility
IVC collapsibility
Attention !!!!!!

Patients should not receive fluids because the SVV or PPV or
IVC collapsibility is high

We - healthy individuals - are all fluid responders

The first question must be << does my patient need an
increase in SV or in CO>>

Dynamic parameters will never answer this question

Clinical examination +++

Biological tests (lactates, SvO2, C.O)
Algorithm for SVV based protocol
Cardiac Output Evaluation
The absolute value of C.O. is meaningless. Hypo, Hyperthermia, Drugs)
ICU patients
Frequent modifications of Mechanical Ventilation and PEEP, TR, Sedation,
General Anesthesia, Surgery, Variations of body temperature in the O.R.,
Substantial blood losses.
SvO2, ScvO2, (a-v)DO2, DO2, VO2.
Adequacy of C.O and oxygen transport, quality of tissue oxygenation.
Pulse Contour Cardiac Output (PCCO)
Pulse contour Cardiac Output (PCCO):
Flaws & Limitations

Aortic Valve disease

Arrhythmias

Quality of the arterial waveform

Frequent & rapid changes in arterial compliance

Need for frequent calibrations - every 4h or before important acquisitions
Minimally invasive???
Maximizing Oxygen delivery in critically ill patients: A
methodologic appraisal of the evidence.
Heyland et al. Crit Care Med 1996;24:517-24

7 randomized trials 1016
patients included

Major problem:
crossover of the patients

Time of intervention
Pre or postoperative in the ICU

Timing of inotropic support
Crit. Care Med 2002;30:1686-92
21 randomized controlled trials
Mortality reduction with
hemodynamic optimization
a.
b.
when treated early before
MSOF
when group mortality is
>20%
SvcO2 use in Sepsis
N Engl J Med 2001;345:1368-1377
Do I need to increase CO ?
ScvO2
Will my patient respond to fluid loading?
SVV
CO response to PLR or fluid loading
Conclusion