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Shock and Monitoring

Samuel A. Tisherman, MD, FACS, FCCMProfessorDepartments of CCM and SurgeryUniversity of Pittsburgh


Shock

Inadequate DO2

“Dysoxia”

Anaerobic metabolism Lactic acidosis

Activation of inflammatory cascades

Organ system dysfunction


ShockNormal cardiovascular system

Pathophysiology of shock

Categories of shock

Resuscitation

Monitoring


Key components of CV systemIntravascular volume

Cardiac outputPreloadHeart rateContractilityAfterload


Key components of CV system

Resistance circuit –arterioles

Distribution of organ flow

CapillariesLeakObstruction to flowShunts

Venous capacitance vessels

Vary venous return


Organ blood flowMost dependent upon mean arterial pressure (MAP)

AutoregulationMaintained during large variations of MAP60-130 mmHgCan be impaired - hypertension


Autoregulation


Supply and demandO2 delivery

HemoglobinSaturationCardiac output

O2 demand

VO2 = DO2 x ERO2

ER = extraction ratio

20-60%


O2 supply dependency

Oxygen delivery

Oxy

gen

cons

umpt

ion

CriticalDO2

CriticalDO2

DysoxiaLactic acidosis


Cytopathic HypoxiaSepsis

Normal oxygen deliveryImpaired mitochondrial O2 utilization

MediatorsInflammatory cytokinesInhibition of pyruvate dehydrogenaseInhibition of cytochrome a,a3 by NOIrreversible inhibition of one or more mitochondrial respiratory complexes by peroxynitritePoly(ADP-ribose) polymerase-1

Reperfusion Injury

ATPXanthine

Dehydrogenase

Hypoxanthine XanthineOxidase

O2

Oxygen radical formationLipid mediator release

Endothelial cell dysfunctionNeutrophil chemotaxisMicrovascular changes

Tissue injury

Ischemia

Reperfusion


It’s not the fall that gets you….


Organ failure

OrganDamage

IschemicInjury

Inflammatory mediators(TNF, NO, free radicals)

Reperfusioninjury


HyperdynamicLow SVR (wide PP)

HypotensionHypodynamic

Low CO (narrow PP)

Pulmonary edema?Distributive shock

SepsisNeurogenic shock

Adrenal insufficiencyLiver failureAnaphylaxis Medications

No Yes

Cardiogenic shockMI

Valvular dzHypovolemiaHemorrhageDehydration

JVD?

No Yes

RV failureObstructive

PETamponade

PTX

Classifications of shock


Hemorrhagic shockMost common cause of hypotension in trauma patients

Initial fluid should be crystalloid

TransfusionHypotensive after 2 L crystalloid (ATLS)Earlier for severe shock

Uncontrolled hemorrhageStop hemorrhageLimited fluid resuscitation


Cardiogenic shockResuscitation simultaneous with revascularization

Patients may need higher than normal filling pressures (poor LV compliance)

Inotropes may worsen ischemia

Pacing may be helpful for relative bradycardia

Intra-aortic balloon pump improves coronary perfusion and decreases afterload


Pulmonary embolismRisk factors

Hypercoagulability, stasis, trauma

PresentationRespiratoryCardiovascular

DiagnosisCT angio, VQ, echo, angio, d-dimer

ManagementAnticoagulation, thrombolytic, embolectomyPrevent the next one -?filter


Cardiac tamponadePentrating trauma more common than blunt

Beck’s triad (hypotension, distant heart sounds, JVD) obscured by hypovolemia

High index of suspicion

Diagnose: echo or pericardial window

Treatment:Need sternotomy or thoracotomy (trauma)Pericardiocentesis (non-trauma)


Septic shockDecreased preload

Hypovolemia (capillary leak)Increased venous capacitance

Vasodilatation

Cardiac dysfunctionVentricular dilatationDecreased ejection fraction

Cytopathic hypoxia


Endstage shock

Cardiacdecompensation

Vasomotordysfunction

Irreversible shockTerminal hypodynamic state


Initial management


Initial managementResuscitation

Ventilation?intubation early

InfusionBolus to effect?bloodClear lactate

Pump therapyInotropic supportAfterload reduction

VasodilatationVasopressor support

Definitive therapyStop bleedingCirculatory assistAntibiotics and drainage/debridement


Monitoring


CVPOnly elevated in disease

RV dysfunctionPulmonary hypertensionLV dysfunctionTamponadeHyperinflationIntravascular volume expansion

Poor correlation with volume responsiveness


PAOP and Preload

Muscle

LVEDV

LVEDP

LAP

PAOP


CVP and PAOP

Kumar, et al. CCM, 2004.


Functional Hemodynamic Monitoring

2-3 heart beats later


Resp variation in pulse pressure

Michard and Teboul. Crit care, 2000. Limitations: spontaneous breathing, arrhythmias.


Passive Leg Raising


Passive Leg Raising

Monnet, et al. CCM, 2012.


Preload EchoDistensibility index

Max-min DIVC x 100%Min DIVC

Collapsibility indexMax-min DIVC x 100%Max DIVC

Resp variability indexΔDIVC = Max-min DIVC x 100%

Mean DIVC

Feissel, et al. Intensive Care Med, 2004.


Mixed venous oxygen - SvO2

Decrease SvO2Decrease DO2

Hb, O2 sat, cardiac outputIncrease O2 demands

Fever, sepsis, exerciseNormal >65%Critical value ~40%

Resuscitation endpoint for sepsis and cardiogenic shock

Sepsis -> maldistribution of blood flowSvO2 normal with tissue dysoxia still present


Oxidative MetabolismGlucosePyruvate Lactate

Acetyl CoA

NADH/FADH2Electron transport chain

ADP 34 ATPO2 H2O

2 ATP Citric acidCycle

Mitochondria

2 ATP

Remember 2:38


Base DeficitDefinition

Amount of base needed to normalize pH with normal PCO2

LimitationsAdministration of bicarbonateAlcohol intoxicationHyperchloremic metabolic acidosisSeizuresPre-existing acidosis


LactateExcess production

Anaerobic metabolismInitial level and time to clearance useful

Decreased metabolism (liver, kidney)

Washout during reperfusion

SepsisIncrease flux of alanine from muscleDecreased PDH activityDecreased hepatic clearanceDysfunctional mitochondrial respiration


Near Infrared Spectroscopy

LocationMuscleStomachBowelLiver

MeasurementsPO2PCO2pHO2 saturation of hemoglobinTissue oxyhemoglobin coupling to cytochrome a,a3 redox

Mitochondrial O2

HyperdynamicLow SVR (wide PP)

HypotensionHypodynamic

Low CO (narrow PP)

Pulmonary edema?Distributive shock

SepsisNeurogenic shock

Adrenal insufficiencyLiver failureAnaphylaxis Medications

No Yes

Cardiogenic shockMI

Valvular dzHypovolemiaHemorrhageDehydration

JVD?

No Yes

RV failureObstructive

PETamponade

PTX

FluidsBlood

Hemostasis

FluidsInotropes

Specific Tx

InotropesIABP

Revascularize

FluidsVasopressors

EGDTxTreat cause

Base deficitLactate SvO2


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