shock in large animals
TRANSCRIPT
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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