shock heraklion

8/6/2019 Shock Heraklion

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New concepts in thepathophysiology of shock

D. Georgopoulos, Professor of Medicine,

Director of ICU, University Hospital of Heraklion,University of Crete, Heraklion


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VO2

(2)

CaO2 = 1.36 x Hb x SaO2 + (0.003xPaO2)

Amount of O2 = Truck volume x CaO2

CaO2


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VO2

2

CaO2 = 1.36 x Hb x SaO2 + (0.003xPaO2)

Amount of arterial O2 = Truck volume x CaO2

CaO2CvO2

CvO2 = 1.36 x Hb x SvO2 + (0.003xPvO2)

Amount of venous O2 = Truck volume x CvO2

VO2 = Truck volume x (CaO2 - CvO2)


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VO2

2

CaO2CvO2

DO2 = SV x HR x CaO2

Fick equation

VO2/min = SV x HR x (CaO2 - CvO2)


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DO2 = SVxHRx(CaO2-CvO2)

VO2

Critical value

Sepsis


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Shock - Definition

Shock = Tissue hypoxia

Arterial blood pressure should not be

used for shock definition


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Shock

Hypovolemic Cardiogenic ObstructiveDistributive

(Vasodilatory)

Cardiac output Cardiac output


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Vasodilatory shock is the final

common pathway for long-

lasting and severe shock ofany cause


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Shock

Hypovolemic Cardiogenic ObstructiveDistributive

(Vasodilatory)

Cardiac output Cardiac output


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Why?


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Landry and Oliver New Engl J Med 2001;345:588

Tissue

hypoxia


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Activation of ATP-sensitive

Potassium Channels

(Open ATP-K+)

Increased synthesis

of NO

Deficiency of

vasopressin

Energy depth

(tissue hypoxia)


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A section of the neurohypophysis from a normal dog

Before After 1 hr of severe hemorrhagichypotension (mean AP


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Tissue hypoxia

(Shock)

Nitric Oxidesynthase

ATP, H+

, lactatein vascular smooth muscle

Vasopressinsecretion

Open KATP

Nitric Oxide

cGMP

Cytoplasmic Ca++

Phosphorylated

myosin

Vasodilation

Vasopressinstores

PlasmaVasopressin

Landry and Oliver New Engl J Med 2001;345:588


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Vasodilatory shock is the final

common pathway for long-

lasting and severe shock ofany cause


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Microcirculation

The microcirculation, with its hugeendothelial surface, is in fact the

largest organ in the human body


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Shock: Complete stasis in

the capillaries

Healthy volunteer

Shock: Some capillariesshowing stasis and others

showing high flow

Orthogonal polarisation

spectral imaging


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Normal Sepsis

De Backer et al. Am J Respir Crit Care Med 2002


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De Backer et al. Am J Respir Crit Care Med 2002;166:98


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De Backer Am Heart J 2004;147:91


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Sakr et al. Crit Care Med 2004;32:1825


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Evolution of small vessel perfusion


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ROC curve for the change in small vessel perfusion

within 24 hrs of the onset of shock


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It is rational to open the

microcirculation during tissuehypoxia

Evidence?


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8 patients with septic shock were fluidresuscitated such as mean AP was > 60 mmHgand CVP > 12 mmHg

After the pressure goal had been reachednitroglycerin infusion was started with an I.Vbolus dose of 0.5 mg and followed bycontinuous infusion of2 mg/hr

The dose was increased and fluids were infuseduntil peripheral circulation seemed to berestored

Lancet 2002; 360:1395


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Patients characteristics

Age 59 (range 27-79)

APACHE-II27 (range 11-37)

The amount of fluids ranged between 2.2and 8.3 L

CVP ranged between 11 and 25 mmHg

Mean AP ranged between 60 to 80 mmHg

Spronk et al. Lancet 2002;360:1395


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Sludged erythrocytes

Before After nitroglycerin


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7 out of 8 patients were discharged from the hospital

1 required renal replacement therapy

1 patient died 6 days after treatment from cerebral haemorrhage


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Take home messages

Vasodilatory shock is the final commonpathway for long-lasting and severe shockof any cause

Microcirculation plays an important(probably the most important) role in thepathophysiology of shock

Therapies targeting the microcirculationmight influence the outcome of patientswith shock

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