K9.Sepsis

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The Pathophysiology of Sepsis /

SIRS and MOF

INFECTION AND TROPICAL PEDIATRIC DIVISION

Department of Child Health

Medical Faculty, University of Sumatera Utara

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Objectives

The Definitions of Sepsis and the SepsisSyndromes.

The Factors that precipitate and perpetuate theSepsis Cascade.

The Pathogenesis of Multiple Organ

Dysfunction in Sepsis.

Treatment options in Sepsis

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What is Sepsis?

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Definitions (ACCP/SCCM, 1991)

Systemic Inflamatory Response Syndrome

(SIRS): The systemic inflammatory

response to a variety of severe clinicalinsults (For example, infection).

Sepsis: The systemic inflammatoryresponse to infection.

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SIRS is manifested by two or more of the

following conditions:

Temperature >38 degrees Celsius or 90 beats per minute.

Respiratory rate>20 breaths per minute

or PaCO2 12,000/cu mm,

10% band forms.

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Definitions (ACCP/SCCM):

Infection: A microbial phenomenoncharacterized by an inflammatory response

to the presence of microorganisms or theinvasion of normally sterile host tissue bythose organisms.

Bacteremia: The presence of viablebacteria in the blood.

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Relationship Between Sepsis and

SIRS

TRAUMA

BURNS

PANCREATITIS

SEPSIS SIRSINFECTION SEPSIS

BACTEREMIA

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Definitions (ACCP/SCCM)

Sepsis:

Known or suspected infection, plus

>2 SIRS Criteria.

Severe Sepsis:

Sepsis plus >1 organ dysfunction.

MODS.

Septic Shock.

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Septic Shock: Sepsis induced with

hypotension despite adequate

resuscitation along with the presence ofperfusion abnormalities which may

include, but are not limited to lactic

acidosis, oliguria, or an acute alterationin mental status.

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Multiple Organ Dysfunction Syndrome

(MODS): The presence of altered organ

function in an acutely ill patient such thathomeostasis cannot be maintained

without intervention.

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Sepsis Criteria (SCCM, ESICM,

ACCP, ATS, SIS, 2001):

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Sepsis Criteria (SCCM, ESICM,

ACCP, ATS, SIS, 2001):

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Clinical Signs of Sepsis

Fever.

Leukocytosis.

Tachypnea.

Tachycardia.

Reduced Vascular Tone. Organ Dysfunction.

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Clinical Signs of Septic Shock

Hemodynamic Alterations

Hyperdynamic State (Warm Shock)

Tachycardia.

Elevated or normal cardiac output.

Decreased systemic vascular resistance.

Hypodynamic State (Cold Shock)

Low cardiac output.

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Clinical Signs of Septic Shock

Myocardial Depression.

Altered Vasculature.

Altered Organ Perfusion.

Imbalance of O2 delivery and

Consumption.

Metabolic (Lactic) Acidosis.

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Levels of Clinical Infection

Level I Locally Controlled.

Level II Locally Controlled,

Leukocytosis. Level III Systemic Hyperdynamic

Response.

Level IV Oxygen metabolism becomesuncoupled.

Level V Shock, Organ Failure.

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Stages In the Development of

SIRS (Bone, 1996) Stage 1. In response to injury / infection, the

local environment produces cytokines.

Stage 2. Small amounts of cytokines arereleased into the circulation:

Recruitment of inflammatory cells.

Acute Phase Response.

Normally kept in check by endogenous anti-

inflammatory mediators (IL-10, PGE2, Antibodies,

Cytokine receptor antagonists).

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Stages In the Development of

SIRS Stage 3. Failure to control inflammatory

cascade:

Loss of capillary integrity.

Stimulation of Nitric Oxide Production.

Maldistribution of microvascular blood

flow. Organ injury and dysfunction.

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Why is Sepsis Important?

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Severe Sepsis

Major cause of morbidity and mortality

worldwide.

Leading cause of death in noncoronary ICU.

11th leading cause of death overall.

More than 750,000 cases of severe sepsis

in US annually.

In the US, more than 500 patients die of

severe sepsis daily.

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Severe Sepsis is deadly

34%

50%

28%

0%

5%

10%

15%

20%

25%

30%35%

40%

45%

50%

Sands,et al Zeni, et al. Angus,et al

Mortality

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Severe Sepsis is Common

0

50

100

150

200

250

300

Severe

Sepsis

CVA Breast

CA

Lung

CA

Incidence

Mortality

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Severe Sepsis is increasing in

incidence

600

800

1000

1200

1400

1600

1800

2001 2025 2050

250

300

350

400

450

500550

600

Severe Sepsis cases US Population

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Severe Sepsis is a Significant

Healthcare Burden Sepsis consumes significant healthcare

resources.

In a study of Patients who contract nosocomialinfections, develop sepsis and survive:

ICU stay prolonged an additional 8 days.

Additional costs incurred were $40,890/ patient.

Estimated annual healthcare costs due tosevere sepsis in U.S. exceed $16 billion.

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Mediators of Septic Response

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Pro-inflammatory Mediators

Bacterial Endotoxin

TNF-

Interleukin-1

Interleukin-6

Interleukin-8

Platelet Activating Factor (PAF)

Interferon-Gamma Prostaglandins

Leukotrienes

Nitric Oxide

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Anti-inflammatory Mediators

Interleukin-10

PGE2

Protein C

Interleukin-6

Interleukin-4

Interleukin-12

Lipoxins GM-CSF

TGF

IL-1RA

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Mechanisms of Sepsis - InducedOrgan Injury and Organ Failure

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Question: Why do Septic

Patients Die?

Answer: Organ Failure

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Organ Failure and Mortality

Knaus, et al. (1986):

Direct correlation between number of organ

systems failed and mortality.

Mortality Data:

1 22% 31% 34% 35% 40% 42% 41%

2 52% 67% 66% 62% 56% 64% 68%

3 80% 95% 93% 96% 100

%

100

%

100

%

#OSF D1 D2 D3 D4 D5 D6 D7

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Pathophysiology of Sepsis-

Induced Organ Injury Multiple Organ Dysfunction (MODS) and

Multiple Organ Failure (MOF) result from

diffuse cell injury / death resulting incompromised organ function.

Mechanisms of cell injury / death:

Cellular Necrosis (ischemic injury). Apoptosis.

Leukocyte-mediated tissue injury.

Cytopathic Hypoxia

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Pathophysiology of Sepsis-

Induced Ischemic Organ Injury Cytokine production leads to massive production of

endogenous vasodilators.

Structural changes in the endothelium result inextravasation of intravascular fluid into interstitiumand subsequent tissue edema.

Plugging of select microvascular beds with neutrophils,fibrin aggregates, and microthrombi impairmicrovascular perfusion.

Organ-specific vasoconstriction.

Infection

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Infection

Inflammatory

Mediators

Endothelial

Dysfunction

Vasodilation

Hypotension Vasoconstriction Edema

Maldistribution of Microvascular Blood Flow

Organ Dysfunction

Microvascular Plugging

Ischemia

Cell Death

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Therapy For Sepsis

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Therapeutic Strategies in Sepsis

Optimize Organ Perfusion

Expand effective blood volume.

Hemodynamic monitoring.

Early goal-directed therapy. 16% reduction in absolute risk of in-house

mortality.

39% reduction in relative risk of in-house

mortality.

Decreased 28 day and 60 day mortality.

Less fluid volume, less blood transfusion, lessvasopressor support, less hospital length of stay.

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Optimize Organ Perfusion

Pressors may be necessary.

Compensated Septic Shock:

Phenylephrine

Norepinephrine

Dopamine

Vasopressin

Uncompensated Septic Shock:

Epinephrine

Dobutamine + Phenylephrine /Norepinephrine

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Control Infection Source

Drainage

Surgical Radiologically-guided

Culture-directed antimicrobial therapy

Support of reticuloendothelial system

Enteral / parenteral nutritional support

Minimize immunosuppressive therapies

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Support Dysfunctional Organ Systems

Renal replacement therapies (CVVHD, HD).

Cardiovascular support (pressors, inotropes).

Mechanical ventilation.

Transfusion for hematologic dysfunction.

Minimize exposure to hepatotoxic andnephrotoxic therapies.

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Experimental Therapies in Sepsis

Modulation of Host Response

Targeting Endotoxin

Anti-endotoxin monoclonal antibodyfailed to reduce mortality in gramnegative sepsis.

Neutralizing TNF

Excellent animal data.

Large clinical trials of anti-TNFmonoclonal antibodies showed a verysmall reduction in mortality (3.5%).

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IL-1 Antagonism

Three randomized trials: Only 5% mortalityimprovement.

PAF-degrading enzyme

Great phase II trial.

Phase III trial stopped due to no demonstrableefficacy.

NO Antagonist (LNMA)

Increased mortality (? Pulmonary Hypertension).

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Antithrombin III

No therapeutic effect.

Subset of patients with effect when concomitant

heparin not given.

Activated Protein C (Drotrecogin alpha / Xigris) Statistically significant 6% reduction in mortality.

Well-conducted multicenter trial (PROWESS).

FDA-approved for use in reduction of mortality in

severe sepsis (sepsis with organ failure).

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Mediator-Directed Therapies

Coagulation System Xigris (Drotrecogin alpha/activated

Protein C

PROWESS Study#MOD Mortality Reduction

Absolute Relative

>4 11% 22%3 8% 24%

2 5% 20%

1 2% 8%

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Corticosteroids

Multiple studies from 1960s 1980s: Not

helpful, possibly harmful.

Annane, et al. (2002): 10% mortality

reduction in vasopressor-dependent septic

shock (relative adrenal insufficiency, ACTH

nonresponders).

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Evidence-Based Sepsis Guidelines

Incorporation of data from the existing medical

literature in the design of guidelines for the care of

patients with severe sepsis and septic shock.

Guideline development strongly advocated by

multiple critical care societies.

Guideline development for the reduction of

mortality in sepsis is part of the 100K lives

Campaign of IHI and is likely to soon become a

JCAHCO requirement.

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Components:

Early Recognition

Early Goal-Directed Therapy

Monitoring

Resuscitation

Pressor / Inotropic Support

Steroid Replacement

Recombinant Activated Protein C

Source Control

Glycemic Control

Nutritional Support

Adjuncts: Stress Ulcer Prophylaxis, DVT Prophylaxis,

Transfusion, Sedation, Analgesia, Organ Replacement


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Evidence Based Sepsis Guidelines


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