SvO2 = SaO2

Risk adapted peri – operative haemodynamic management
Clinical relevance of
perioperative ScvO 2 monitoring
___________________________________________
Euroanaesthesia 2007 Meeting
Munich, Germany, 9.-12. June 2007
Claus-Georg KRENN
Dept. of Anaesthesia and General Intensive Care, University Vienna
claus.krenn@meduniwien.ac.at

standard hemodynamic monitoring
___________________________________________________
31 of 36 medical shock
patients:
– resuscitated to normal
MAP and CVP
– have global tissue hypoxia
(Scv02 < 70% ) and
– lactate >2 mmol/L
Rady, AJEM 1994

Rady, AJEM 1994
MAP
[mmHg]
180
150
120
90
60
30
Standard hemodynamic monitoring
might be not enough
to assess tissue oxygenation in
patients at risk !!!
n= 1232
DO2 ml*m-2 *min-1 100 300 500 700 900 1100

Für die Entwicklung der Lehre vom Kreislauf war es gewiss
ein Verhängnis, dass das Stromvolumen verhältnismäßig so
umständlich, der Blutdruck aber gar so leicht bestimmbar ist -
deshalb gewann das Blutdruckmanometer einen geradezu
faszinierenden Einfluss, obwohl die meisten Organe gar
nicht Druck, sondern Stromvolumen brauchen.
A. Jarisch
„Kreislauffragen“ ; 1928

The conventionally measured variables such as bl od
pressure, heart rate and urine output were of little
prognostic value.
Only variables related to volume and flow
(blood volume, cardiac output, oxygen delivery and consumption)
had a significant prognostic value.
W. C. Shoemaker 1979

Macrohemodynamics
═
regional blood flow

Macrohemodynamics
═
regional blood flow

Macrohemodynamics
═
regional blood flow
need for a relieable clinically applicable and
useful indicator of adequate tissue oxygenation

Macrohemodynamics
═
regional blood flow
need for a relieable clinically applicable and
useful indicator of adequate tissue oxygenation
monitoring should be dynamic -
interventions immediately affect parameter

physiologic key question of oxygen transport
___ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __
… adequacy or mismatch

the controversy of increasing O 2 transport
___________________________________________________________
10
5
0
-5
-10
-15
-20
-25
-30
0 2 4 6 8 10 12 16 20 24
„goal directed therapy“
GDT
… increase O 2 delivery to (supra)normal values !!!
WC Shoemaker et al. 1973, Arch Surg 106

the controversy of increasing O 2 transport
____________________________________________________
Hayes et al., N Engl J Med 1994

ScvO 2
___ __ __ __ __ __ __ __ __ __ ___
VO 2 DO 2 DO 2 VO 2
Stress PaO 2 PaO 2 Anesthesia
Pain Hb Hb Hypothermia
Shivering CO CO
Fever Hypovolemia

Oxygen delivery (DO 2)
______________________________
1) not necessarily increases
oxygen consumption
2) why not measure
oxygen consumption ?
3) use mixed venous oxygen
satturation as marker
of oxygen consumption
SvO 2

Meta – analysis of hemodynamic optimization
________________________________________________________________

Meta – analysis of hemodynamic optimization
___________________________________________________________

from SvO 2 to mixed central venous O 2 satturation
___________________________________________________________________
.
ScvO 2
SvO 2

from SvO 2 to mixed central venous O 2 satturation
___________________________________________________________________
.
V. cava sup.
- before the
right heart
ScvO 2
SvO 2

early goal directed therapy
___ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ _
E. Rivers et al.;
N Engl J Med 2001

early goal directed therapy
___ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ _

early goal directed therapy
___ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ _
E. Rivers et al.;
N Engl J Med 2001

ScvO 2 - continuous measurments
_________________________________________________
continuous fiberoptic
venous oxymetry

ScvO 2 - continuous measurments
_________________________________________________

is ScvO 2 a valuable parameter for monitoring ?
_________________________________________________________
� in all patients ?
� in all clinical
situations ?
� without endangering
by itself ?
� with impact on
prognosis ?

ScvO 2 in critically ill patients
___ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ ___
� 61 patients, paired measurment on admission
� correlation coefficient 0.945
� both parameters are closely related and
interchangeable for the first evaluation
Ladakis et al. Respiration 2001:68

ScvO 2 in critically ill patients
_____________________________________________
� continuously measured in high-risk patients,
paired measurment
Reinhart et al. ICM 2004: 30

ScvO 2
___ __ __ __ __ __ __ __ __ __ ___
� was unaffected by changes in
physiologic variables (pH, temp., a.s.o.)
� averaged 7 ± 4 % higher
� paralleled SvO 2 in more than 90%
� correlation coeff. r = 0.96

ScvO 2 in septic shock patients
___ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __
� 16 patients, paired measurments over 24 h
Varpula et al., ICM 2006; 32:1336

ScvO 2
___ __ __ __ __ __ __ __ __ __ ___
� difference between SvO 2 and ScvO 2
varies considerably over time
� ScvO 2 being higher at all TP
� ScvO 2 inadequate tool to estimate the
flow-weighted oxygen balance of the whole
body (SvO 2 )
� but accurately reflects hypovolemia

ScvO 2 in critically ill patients
______________________________________________
� 53 patients, surgical and medical
� calculating VO 2 on basis of ScvO 2 produced
unaccaptable large errors
� difference might be attributed to mixing with
coronary sinus blood
Chawla et al., CHEST 2004:126

ScvO 2 in perioperative patients at risk
__________________________________________________
� Morbidity
� Increased length of hospital stay
� Mortality

high risk patients
__________________________________
� Emergency abdominal aortic surgery
� Trauma, such as fractured neck of femur
� Neurological
� Cardiovascular
� severe valvular heart disease
� aortic dissection
� Gastrointestinal
� Colon resection
� large and small bowel obstruction
� Pancreatic surgery

Reason for being high risk
________________________________________
� Co-morbidity
� elderly patients with significant medical problems
� Type of surgery
� often long procedure with significant blood loss
fluid shift, electrolyte and nutritional problems
and possibility of post-op pain (effects breathing)
� abdominal surgery is associated with physiological
stress response
� Emergency or elective
� Patients who present with urgent emergency
cases have worse outcomes

ScvO 2
___ __ __ __ __ __ __ __ __ __ ___
� fluctuations occur in the post-op period
� not only associated with DO 2 but also
related to oxygen consumption
� ScvO 2 changes are independently
associated with postoperative complications
ScvO 2 lowest value (cut off 64 %) was
significantly lower in patients who
developed complications

• absolute values
differed unaccaptable
r = 0.76
• however the trend was
clinically acceptable as
substitute of SvO 2

ScvO 2 in cardiac surgical patients
___ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ _
� 60 patients, 5 TP, 300 paired measurments
Sander et al. ICM 2007

ScvO 2
___ __ __ __ __ __ __ __ __ __ ___
� weak correlation over all measurments
� more pronounced association in
values below 70%
� attributed to increase of oxygen extraction
rate of splanchnic circulation in the course of
ACBP crafting
� ScvO 2 might overestimate SvO 2
� thus only high values can exclude tissue hypoxia

� Goal directed therapy – setting ,
aiming at adequate DO 2 by improving CO
(stroke volume optimization) by
fluid and catecholamine administration
� resulted in reduced mortality and HLoS

ScvO 2
___ __ __ __ __ __ __ __ __ __ ___
� reflects the degree of oxygen extraction
from the upper part of the body including
the brain
� values are slightly higher than SvO 2
� difference to SvO 2 might vary with
cardiovascular insufficiency
� thus in case of low SvO 2 it should not be
used alone but in combination with other
markers

Nguyen et al., Crit Care Med 2007, 35

… perfusion –
deficit ?
practical aproach ?
________________________________
advanced
monitoring
global or regional
problem ?
S cvO 2 ? EGDT

Conclusion ScvO 2 - monitoring
_______________________________________
� identify high risk patients and implement
ScvO 2 monitoring early - as easy as with
insertion of the central venous catheter

Conclusion ScvO 2 - monitoring
_______________________________________
� implement early in high risk patients
� check signs of reduced tissue perfusion
s.a.: complete hemodynamic evaluation
(CO, stroke volume ~ variation, GEDV,
lactate, PDR of ICG, diuresis)

Conclusion ScvO 2 - monitoring
_______________________________________
� implement early in high risk patients
� check signs of reduced tissue perfusion
� rely on the course targeting your
hemodynamic goals which in almost all cases
mirrors the course of SvO 2

Conclusion ScvO 2 - monitoring
_______________________________________
� implement early in high risk patients
� check signs of reduced tissue perfusion
� rely on the course
� treat according to a standardized algorythm
aiming at adequate (regional) perfusion

focus on : „early and goal directed“
___________________________________________________________________________

Gemischtvenöse Sättigung SvO2
• SvO2 = SaO2 – VO2
folgt aus der Umwandlung von
• VO2 = CO × (CaO2 – CvO2)
Sauerstoffverbrauch berechnet
CO ⋅ Hb ⋅ 1,34

ScvO 2
___ __ __ __ __ __ __ __ __ __ ___
� adequately reflects hypovolemia
� only high values [ ›70%] can exclude
inadequate oxygen delivery
� is no general estimate of SvO 2