Organ Failure Flashcards
define lymphatics
blind ended capsillaries that dump into venous system
what maintains the flow of lymphatics?
muscle contractions since it is low pressure and valved
how much of the body weight is fluid? what is this fluid comprised of?
60% = intracellular 40% + extracellular 20% (plasma 4% + interstitium 16%)
which circulation is this?
lymphatic vessel
which circulation is this?
arteriole/venule
gaps in endothelium allow movement of fluid
what forces interstitial fluid into lower pressure venules and lymphatics?
hydrostatic pressure
here for Liz Brain
list the main controls of fluid movement
hormones - RAAS, ANP (cardiomyocytes)
receptors - osmoreceptors, baroreceptors
osmotic/hydrostatic forces
integrity of vascular system
what does RAAS do that controls fluid movement?
vasoconstriction and water retention
what does atrial natriuretic peptide (ANP) do that controls fluid movement?
promotes renal sodium and water excretion and stimulates vasodilation
define shock
cardiovascular collapse - systemic hypoperfusion due to macro/micro-circulatory failures
describe the outcome of shock (pathogenesis)
hypotension > impaired tissue perfusion > cellular hypoxia > anaerobic metabolism > cellular degeneration > cell death
describe the progression of shock to an irreversible state in terms of metabolism
hypovolemic shock > initial compensation > progression, metabolism shift to glycolysis > progressive morphological deterioration of cells
list the types of shock via macrocirculatory failure and define each
- cardiogenic - failure of heart to properly pump blood
- hypovolemic - reduced circulation of blood volume by massive blood/fluid loss
list examples of cardiogenic macrocirculatory failure
myocardial infarction
ventricular tachycardia
HCM
DCM
cardiac output obstruction (pulmonary embolism, aortic stenosis)
pericardial tamponade
ID pathology - what type of shock?
cardiogenic shock - macrocirculatory failure in horse
expanded pericardial sac, cardiac tamponade
define cardiac tamponade
compression of heart caused by fluid collecting in sac surrounding the heart
*example of cariogenic shock > macrocirculatory failure
ID pathology
aortic rupture and cardiac tamponade
ID pathology
hemangiosarcoma at R auricle and cardiac tamponade
list the types of shock due to microcirculatory failure
blood maldistribution
1. anaphylactic shock
2. septic shock
3. neurogenic shock
Describe how blood is maldistributed in microcirculatory failure?
decreased peripheral vascular resistance and polling of blood in peripheral tissue
what type of hypersensitivity of anaphylactic shock?
type I (IgE) hypersensitivity
what mainly causes septic shock?
endotoxemia from gram negative bacilli
what causes neurogenic shock?
trauma, spinal cord injury, electrocution, fear, emotional stress
anaphylactic shock pathogenesis
exposure of insect/plant/drug/vaccine > IgE mediated mast cell degranulation > histamine/mediators > systemic vasodilate and increased vascular permeability > blood hypotension > tissue hypoperfusion
septic shock (most common) pathogenesis
Toxin (ex. LPS from gram negative bacterial cell walls) > LPS forms a complex with blood proteins > LPS bind to TLR-4 > down-regulation of anticoagulants (tissue factor pathway inhibitor and thrombomodulin) and increasing production of IL-1, IL-6, TNF (monocytes/macrophages)
list the major antithrombotic systems
- protein c - protein s thrombomodulin system
- antithrombin III
- tissue factor pathway inhibitor
LPS intoxication is ___ dependent
dose
Describe the pathogenesis of high production of TNF, IL-1, IL-6/8, NO, and PAF leading to septic shock?
High production of TNF, IL-1, IL-6/8, NO, and PAF promotes systemic vasodilation and increased capillary permeability>intravascular plasma protein loss decreases oncotic forces > additional intravascular fluid loss > toxins and cytokines induce loss of peripheral vascular tone > hypotension > hypoperfusino > septic shock
LPS effect on endothelium triggers coag cascade and damages capillaries, which can lead to what two things?
DIC (disseminated intravascular coagulopathy)
ARDS (acute respiratory distress syndrome)
what can be a result from pathological activation of coagulation due to disseminated intravascular coagulopathy (DIC)?
- small blood clot form inside blood vessels throughout body
- consumption of coag proteins and platelets > disruption of normal coag causing abnormal bleeding
- clots plug normal blood flow to organs > ischemic injury
list what could trigger disseminated intravascular coagulopathy (DIC)
bacterial endotoxins, sepsis
parasites
viruses
carcinoma, hemangiosarcoma, leukemia
heat stroke, antigen-Ab complexes
*diffuse endothelial damage and/or generalized platelet activation initiates
define acute respiratory distress syndrome (ARDS)
multifactorial source of injury to respiratory capillary endothelium (primary)
epithelium (secondary)
list the main causes of acute respiratory distress syndrome (ARDS)
endotoxemia, sepsis, extensive trauma (hit by car), DIC, pancreatitis
ID pathology
ARDS
blue - inflammatory cells
dilated blood vessels
Describe the pathogenesis of ARDS
Damaged vessels allow leakage of fibrin and fluid > formation of hyaline membranes (protein, fibrin, surfactant and cell debris) > resolution through scarring
*Liz Brain
neurogenic shock pathogenesis
trauma, spinal cord injury, fear, electricity > triggers generalized ANS > sympathetic tone lost, parasympathetics dominate > massive peripheral dilation and bradycardia > pooling of blood > hypoperfusion > neurogenic shock
what types of microcirculatory shock trigger cytokines and which triggers autonomic discharge?
anaphylactic and endotoxic shock - cytokine
neurogenic shock - autonomic discharge
describe what occurs at each stage in the development of shock
compensation - increased HR, vasoconstriction, ADH and AII released > increased BP and blood diversion to vital tissue
progression - anaerobic metabolism > acidosis > peripheral vasoconstriction cannot be maintained so dilation occurs
irreversible - cell and tissue necrosis
which of the following stages of shock is reversible?
compensation
define cause (etiology) of death
injury or disease that began a sequence of events that ultimately led to death
define mechanism (pathogenesis) of death
biochemical or physiological abnormalities that result in death
define death
cessation of all vital functions of body - heartbeat, brain activity, and respiration
