Pierre SQUARA, MD Clinique Ambroise Paré, Neuilly

Pierre SQUARA, MD

Clinique Ambroise Paré, Neuilly

Should we (can we) Should we (can we) measure and optimize measure and optimize

VOVO22 in shock in shock

I.FundamentalsI.Fundamentals of hemodynamicsof hemodynamics

DeliveryDelivery

ConsumptionConsumption

Neededconsumption

I.FundamentalsI.Fundamentals ofof hemodynamicshemodynamics

DeliveryDelivery

ConsumptionConsumption death

life

Critical delivery

Neededconsumption


VOVO22

DODO22

NeededVO2

Critical DO2 DeliveryDelivery

ConsumptionConsumption

depend. Supply independency

Critical delivery

Neededconsumption

Lactate

Gnu uptake (/needs)Gnu deliveryGnu extraction Gnu density inGnu density outGnu transit time

VO2 (/needs)DaO2 EO2 SaO2

SvO2

CO

RangersRangers Doctors Doctors (SRLF 2001)(SRLF 2001)


100%0% 0% 0%0%0%

5%35% 15% 95%50%85%

Limitations in VO2 use arenot theoretical but practical then, must be reassessed periodically

A whole body VO2 equal to needs is not a garantee that circulation is adequate for each cell

But it is a pre-requisite ! Macro circulation must be stabilized before looking at the micro circulation.

Always consider the balanceAlways consider the balancebetween the VObetween the VO2 2 and and the needed VOthe needed VO22

I.FundamentalsI.Fundamentals of hemodynamicsof hemodynamics

Gattinoni L et al, In: Pinsky & Payen ed. Functional hemodynamic monitoring.

Springer 2005. p. 70-86.

II. Should we assess VOII. Should we assess VO22? ?

Key variableKey variableVO2 = plateau

Derived variablesDerived variablesDecreasing lactate CO =« good » SvO2 =« good »

Derived of derived variablesDerived of derived variablesAcceptable blood pressureClinical improvement

Prognostic value Prognostic value (AUC)(AUC)

0.72

0.700.54 (0.69)0.55 (0,68)

0.660.66

Squara et al J Crit Care, 1994

VO2 = CO x 1.34 x Hb x (SaO2 – SvO2)

Key variableVO2 = plateau

Derived variablesDecreasing lactate CO SvO2

Derived of derived variablesAcceptable blood pressureClinical improvement

Physiologic interestPhysiologic interest

Monitoring interestMonitoring interest

II. Should we assess VOII. Should we assess VO22? ?

Normal CO =2.3 – 3.2 L/min.m2 according to age

Increased CO Hypermetabolism Anemia Hypoxemia Impaired O2 tissue diffusion, utilization

Decreased CO Hypometabolism, general anesthesia Hypovolemia, hypertension Impaired pump function

Normal SvO2 = 68 – 74%

Increased SvO2 > 75% Hypometabolism, general anesthesia Hyperdynamic shunts Mitochondrial blockade

Decreased SvO2 < 68% Hypermetabolism Anemia Hypoxemia Low cardiac output,

II. Should we assess VOII. Should we assess VO22??

Is a specific value of Is a specific value of CO or SvOCO or SvO22 normal normal

adaptative adaptative or pathologic ?or pathologic ?

0,0

0,5

1,0

1,5

2,0

2,5

3,0

3,5

CO in L/min/m2

0 10 20 30 Min.

SvO2

0,3

0,4

0,5

0,6

0,7

VO2

100

133

166

200

233

PEP 15 PEP 10PEP 5

PEP 0


22

33

44

0.820.82 0.760.76 0.70.7 SvOSvO22

COCO

If If Stable Hb Stable Hb Stable SaOStable SaO22

Septic shockSeptic shock

CardiogenicCardiogenic shockshock5500

110000

115500 220000

Basal valueBasal value

VOVO22

DysoxiaDysoxia

No proof that CO orNo proof that CO orSvOSvO22 values are adequate to needs values are adequate to needs

VOVO22 = plateau unique = plateau unique

quantitative targetquantitative target


33 44 55 Ca-vOCa-vO22

DO2

VO2

True values

+10% CO or SvO2

CO = -0.5 L/min

Effects of systematic errors (Squara et al ICM, 2004)

III. Can we assess VOIII. Can we assess VO2 2 ??

20% variability in CO10% variability in CaO2

10% variability in SvO2

Effects of random errors (Squara et al ICM, 2004)

DO2

VO2


Additional supply dependency • Increased metabolic needs • Conformance• Non oxidative uptake

DO2

VO2

In any case these additional needs are part of the needs and must be :

• Limited• Balanced by appropriate supply

The ability to identify the critical DO2 point is marginally affected


VO2 using gas VO2 using PAC

On the same unshocked patients, it has been observed different curves (Phang, AJRCCM 1994, Mira, Chest 1994, Hanique, ICM 1993)

But the global plateau upsloping is usually easy to distinguish from O2 supply dependency

And new devices (CCO) allow decreasing the random errors, therefore the global upsloping is usually <10%


VO2

DO2

SvO2Optimal EO2 = Optimal EO2 = 30%Optimal EO2 = 40%

IV. Is there an alternative?IV. Is there an alternative?

DODO22

VOVO22

Method 1 :Method 1 :

Sum of 2 sums of squared residuals Sum of 2 sums of squared residuals John-Alder et al. Am J Physiol 1981John-Alder et al. Am J Physiol 1981

Method 2 : Method 2 :

Combined analysis of lactate Combined analysis of lactate variation variation (Gilbert et al, ARRD, 1986)(Gilbert et al, ARRD, 1986)

Adequate Adequate DODO22

Too low Too low DODO22

Too Too highhigh DODO22

VOVO22 plateau determination plateau determination

V. ToolsV. Tools

The crit DOThe crit DO22 (needed VO (needed VO22))

can be identifiedcan be identifiedIn 75-100% of cases In 75-100% of cases using 5 pointsusing 5 points

www.hemodyn.com

Always consider:Always consider:

« Matching the VO« Matching the VO22 and needed VO and needed VO22 » »

VOVO22 matches O matches O22 needs when: needs when:

1.1. Clinical status improvesClinical status improves

2.2. Lactate decreasesLactate decreases

3.3. CO and SvOCO and SvO22 are in are in empiricallyempirically expected expected ranges according to ranges according to estimatedestimated needs needs

4.4. VOVO22 reaches a plateau reaches a plateau

Conclusion Conclusion

My own guidelineMy own guideline

VO2 = plateau unique quantitative target

OK, If lactate decreases, bloodpressure increases and clinical status improves

CO and SvO2 inside acceptable rangesbut empirical objectives

Simple

Ressusitated but unstable

Persisting shock

Pierre SQUARA, MD Clinique Ambroise Paré, Neuilly

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