shock in large animals

8/11/2019 Shock in Large Animals

1/13

4/27/

Kira Epstein, DVM, DACVS

Objectives

! Understand how select large animaldiseases result in shock

! Understand pathophysiology and

treatment of endotoxemic shock

Definition

! Cell Energy Needs >

Cell Energy Production! 1 Oxygen Limited

" Decreased DO2

" Inability to Use O2


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DO2=Q!CaO2

CaO2=1.34[Hb]SaO2!0.003 PaO2

Q=HR!SVPreload

AfterloadContractility

Hypovolemic Shock

!

Decreased circulatingblood volume

" Whole blood loss

" Fluid loss

!"preload!"SV

!

HR!"SV="Q

Hypovolemic Shock

!

Acute blood loss" Uterine artery bleed

"

Guttural pouch mycosis

" Hemoabdomen

http://vethospital.huji.ac.il/departments/equine/cases/Gutteral-pouch-mycosis_14_2.jpg


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Cardiogenic Shock

! Due to cardiac dysfunction"

Uncommon in large animals" Myocardium, valve, arrhythmia

! "SV" "contractility

" $afterload

"

"preload

! "HR

!!!"Q

Cardiogenic Shock

!

Myocardial dysfunction

" Monensin toxicity

" Sepsis

!

Valvular dysfunction

" Cordae tendonae rupture

!

Arrhythmia

" 3rddegree AV block

" Ventricular tachycardiahttp://www.iahp.com.au/productimages/byrumen%20bag.jpg

Obstructive Shock

! Physicalobstruction toblood flow

"

To the heart" From the heart

!"SV"

"preload

"$afterload

!

HR!"SV="Q


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Obstructive Shock

!

To the heart

"

Pericardial effusion:traumaticreticulopericarditis inruminants

"Abdominal distension:bloat in ruminants, largecolon in horses

!

From the heart"

Embolism

http://www.cvm.tamu.edu/acvp/hardwaredisease/1.JPG

Metabolic Shock

!

Inadequate ability tomeet energydemands

" Decreased oxygen inblood

#"[Hb]

#"SaO2

" Increased tissue

demand

Metabolic Shock

!"[Hb]anemia

" Red maple leaf

toxicosis," Haemonchus infection

in small ruminants,

" Copper toxicity insheep

http://www.sheepandgoat.com/HairSheepWorkshop/Images/barberpoleworm.jpg

http://images.mooseyscountrygarden.com/weather-seasons/autumn-leaves/red-maple-tree.jpg


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Metabolic Shock

!"SaO2

"

Respiratory dysfunction" CO toxicity

" Methemoglobinemia

!

Increasedtissuedemand

" Septicfoal

Not that simple

!

Example: Large colon volvulus !

" Sequestering fluid in the colon (hypovolemic),

" Leaking endotoxin through the colon

(distributive), and

" Has abdominal distension that may impairthe venous return (obstructive)

Endotoxemic Shock

! Common cause ofshock in large animals

!

Associated with:" GI disease

# Enterocolitis

# Grain overload

# Strangulating lesions


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Endotoxemic Shock

!

Associated with:" Pleuropneumonia

" Endometritis and

retained placenta

" Mastitisespeciallycoliform mastitis

http://www.saanendoah.com/gifs/udder1.gif

Endotoxin

!

Structuralcomponent of thecell wall in gramve bacteria

!

Released duringdeath or rapidreproduction ofgram ve bacteria

Endotoxin

!

Lipopolysaccharide(LPS)

" Inner (lipid A)toxic

qualities," Middle

(oligosaccharide), and

" Outerserologicaldifferences in differentbacterial species

https://reader010.{domain}/reader010/html5/0611/5b1dcdf162dba/5b1dcdf473da8.jpg


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Endotoxin

!

Binding of endotoxin toeffector cells

(mononuclear cells,

endothelial cells, etc)

!synthesis of

inflammatory mediators

http://www.nature.com/nature/journal/v420/n6917/images/nature01326-f1.2.jpg

LPS LPB+

M

CD14

TLR-4

NF!B

LPS

Cytokines

!

Neutrophil activation and adhesion toendothelium: TNF-%and IL-1

!

Endothelial cell activation (TNF-%)procoagulant activity, NO andeicosanoid production

!

Stimulate mononuclear andendothelial cells cytokine production(TNF-%)


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Cytokines

!

Act centrally to producefever, depression,decreased appetite (all)

!

Stimulate ACTH release(TNF-%and IL-1)

!

Induce hepatic acutephase protein (i.e.fibrinogen) production(IL-1 and 6)

http://tell.fll.purdue.edu/JapanProj/FLClipart/Verbs/fever.gif

AA metabolites

!Cyclooxygenase!

eicosanoids:" TxA2 stimulates platelet

aggregation and

vasoconstriction,

" PGE2 from

hypothalamus leads tofever

AA metabolites

!

Lipoxygenase!leukotrienes:

! LTB4 attracts and

activates neutrophils,

! LTC4, LTD4, and

LTE4 vasoconstrict,bronchoconstrict, and

increase vascularpermeability


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Other

!

Histamine

"Released from mast cells activated bycomplement or cytokines

"$vascular permeability

"

Dilation of arterioles and constriction oflarge arteries.

!

Anti-inflammatory

" Cytokine induced corticosteroid release

"

IL-10

"

Lipoxins from aa metabolites

Physical Examination

!

Variable severity

! &Temperature

!

Injected scleral vessels

!

Toxic line on mm

! Signs of coagulopathy/DIC

Bloodwork

! Leukopenia due to

neutropenia with leftshift

! Dehydration

! Azotemia

! Hypoproteinemia


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Treatment

!

Fluids +/- Pressors! Underlying disease

treatment

" Drain pleural fluid,

" Remove dead bowel,

" Lavage uterus,

" Antimicrobials

Treatment

!

Bind endotoxin

" In GI tract:

# Biosponge (di-tri-

octahedral smectite)

# Activated charcoal

Treatment

! Bind endotoxin

! In blood

! Hyperimmune plasma,

! Hyperimmune serum,

! Polymixin B

! Phospholipid emulsion

http://www.gambrobct.com/Images/plasma.jpg


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Treatment

!

Block the response" NSAIDs

" Pentoxyfilline

" DMSO

shock in large animals

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