L80: shock and sepsis

what is shock triggered by?

decreased perfusion and oxygen delivery to tissues leading to cells not reaching their metabolic requirement

what is shock?

an imbalance between oxygen delivery to the tissues (DO2) and tissue oxygen consumption/demand (VO2) by the tissues. Specifically, oxygen delivery is less than oxygen consumption/demand

how many ATP are made with aerobic metabolism?

36

how many ATP are made with anaerobic metabolism?

2

what does blood pressure depend on?

1. cardiac output

2. systemic vascular resistance

what does cardiac output depend on?

1. heart rate

2. stroke volume

what does CaO2 depend on?

1. Hg

2. SaO2

3. PaO2

what is SaO2?

saturation of oxygen in arterial blood

what is PaO2?

amount of oxygen dissolved in plasma

what does stroke volume depend on?

1. preload

2. afterload

3. contractility

what is CaO2?

amount of oxygen in the artery

when will oxygen consumption by cells increase?

1. sepsis

2. seizures

3. heat stroke

4. malignant hyperthermia

what acts as the transport for oxygen to reach tissue cells?

1. hemoglobin

2. erythrocytes

what acts as the ventilator for oxygen to reach tissue cells?

respiratory system

what acts as the pump for oxygen to reach tissue cells?

heart

what acts as the tubing for oxygen to reach tissue cells?

circulatory system

what do the adrenal glands do if the body is in hypoxic conditions and why?

will produce glucose to create energy for the cells

why does the brain trigger the release of vasopressin/ADH if the body is in hypotensive conditions?

to promote water reabsorption in the kidneys, increasing blood volume and raising blood pressure to counteract hypotension.

what does RAAS do if the body is hypotensive?

increases reabsorption of sodium from urine to increase the volume that is circulating

shock is a syndrome triggered by ______ perfusion and _______ delivery to tissues. These will compromise ____ metabolic requirements

1. decrease

2. oxygen

3. cell

due to low oxygen content, the ______ cellular respiration will switch to ____ in which pyruvic acid will not enter the mitochondria to produce enough energy in the form of ATP

1. aerobic

2. anaerobic

during states of hypotension/hypoxia, different ______ will get stimulated, sending signals to the _____. This organ will increase the activity of ______ to produce ______ and ______ to compensate

1. receptors

2. brain

3. sympathetic nervous system

4. tachycardia

5. vasoconstriction

what is circulatory shock?

reduce blood flow to tissue

what are the types of circulatory shock?

1. hypovolemic

2. distributive

3. cardiogenic

4. obstructive

what is hypoxic shock?

decrease oxygen content on blood

what is metabolic shock?

cells are unable to utilize fuel sources

give an example of hypoxic shock?

1. severely anemic patient

2. severe respiratory disease where lungs cannot exchange oxygen

give an example of metabolic shock

patient with severe hypoglycemia

what is the most common cause of shock in veterinary medicine?

hypovolemic shock

what are causes of hypovolemic shock?

1. loss of intravascular fluid (plasma)

2. blood loss (hemorrhagic shock)

what are causes for loss of intravascular fluid with hypovolemic shock?

1. severe dehydration

2. burns

3. third spacing

4. polyuria

what is the treatment for hypovolemic shock?

1. IV fluids

2. blood

what is distributive shock associated with?

maldistribution of blood flow that some tissues do not receive adequate oxygen delivery

what is distributive shock caused by?

1. severe systemic vsaodilation and pooling of blood in peripheral capillary beds

2. lack of venous tone

3. increased systemic vascular resistance

what causes lack of venous tone leading to distributive shock?

1. sepsis

2. anaphylaxis

3. trauma

what is the treatment for distributive shock?

1. fluids

2. vasopressers

what vasopressers are given for distributive shock?

1. epinephrine

2. norepinephrine

3. dopamine

what causes cardiogenic shock?

1. poor myocardial function

2. cardiac arrhythmias

3. cardiac tamponade

what can cause poor myocardial function leading to cardiogenic shock?

1. congestive heart failure

2. dilated cardiomyopathy (dogs)

3. hypertrophic cardiomyopathy (cats)

what is CONTRAINDICATED as treatment for cardiogenic shock?

will NOT give fluid therapy

what is the mechanism behind cardiogenic shock>

low cardiac output = a decrease in blood flow from the heart

what causes obstructive shock?

a physical obstruction of blood flow that results in decreased preload and decreased cardiac output

what are examples of things that can cause obstructive shock?

1. GDV

2. caval syndrome (heartworm)

3. pericardial effusion

4. tension pneumothorax

5. pulmonary embolism

what are examples of things that can cause obstructive shock in large animals?

1. right displaced abomasum that has turned on its root

2. mesenteric root torsions (neonates)

what is septic shock?

sepsis with arterial hypotension despite adequate fluid replacement

what is septic shock identified by?

1. persistent hypotension requiring vasopressors to maintain MAP above 65mmHg

2. serum lactate level greater than 2.5 despite adequate volume resucitation

what is the classic example of distributive shock?

septic shock

what is unstressed volume?

amount of blood that needs to remain in venous system so it does not collapse

what is stress volume?

pulls blood from venous to the heart

what happens when there is a massive vasodilation?

there will be an increase in unstressed venous volume

how is venous dilation affected with septic shock?

1. increase in unstressed volume

2. decrease in venous return, preload. and cardiac output

how is arterial dilation affected with septic shock?

1. hypotension

2. decrease organ perfusion

what is bacteremia?

the presence of viable bacteria in the bloodstream, often causing no symptoms

what is endotoxemia?

the presence endotoxins (lipopolysaccharides from the cell wall) of gram-negative bacteria in the blood

what is SIRS?

systemic inflammatory response syndrome

what parameters are evaluated for SIRS?

1. temperature

2. heart rate

3. respiratory rate

4. white blood cells

5. band cells

what is the limitation for SIRS?

lack specificity yielding many false positives and overdiagnosis of sepsis in non-sepsis patients

how may SIRS present on exam?

1. look extremely sick

2. hypoglycemia

3. bad renal/liver parameters

4. leukopenia to leukocytosis

what is the primary site of infection in adult feedlot cattle?

lungs and GI

what is the primary site of infection in dairy cattle?

1. milk

2. uterus

3. mammary glands

what happens when there is excessive activation of inflammation?

1. vascular hypo-responsiveness

2. glycocalyx degradation

3. increased endothelial permeability

4. hypercoagulable state

5. tissue damge

6. multiple organ dysfunction

7. death

what is the clinical manifestation of multiorgan dysfunction syndrome in the heart?

1. decreased contractility

2. arrhythmias

what is the clinical manifestation of multiorgan dysfunction syndrome for coagulation?

DIC

what is the clinical manifestation of multiorgan dysfunction syndrome in the endocrine system?

corticosteroids insufficiency

what is the clinical manifestation of multiorgan dysfunction syndrome in the GI system?

1. constipation

2. diarrhea

3. ileus

4. regurgitaion

5. vomiting

what is the clinical manifestation of multiorgan dysfunction syndrome in the liver?

1. decreased albumin production

2. decrease coagulation factor synthesis

3. jaundice

what is the clinical manifestation of multiorgan dysfunction syndrome in the kidneys?

acute kidney injury

what is the clinical manifestation of multiorgan dysfunction syndrome in the nervous system?

1. encephalopathies

2. convulsions

what is the clinical manifestation of multiorgan dysfunction syndrome in the lungs?

1. acute lung injury

2. acute respiratory distress syndrome

what are the stages of shock?

1. compensated shock

2. early, decompensated shock

3. late, decompensated shock

what are the six persfusion parameters evaluated on physical exam?

1. mentation

2. temperature

3. mucous membrane color

4. capillary refill time

5. heart rate

6. pulse quality

what additional parameters can be used to assess shock?

1. lactate

2. shock index

3. urine production

what shock index is normal for dogs?

below 1

what shock index is normal for cats?

below 1.6

what lactate is normal?

below 2.5 mmol/L

what urine output is normal?

1-2 ml/kg/hour

how is blood pressure during compensated shock?

normotension

how is heart rate during compensated shock?

tachycardia

how is pulse quality in compensated shock?

hyperkinetic, bounding

how is CRT in compensated shock?

shorter (<1 sec)

how is mucous membrane color in compensated shock?

hyperemic or normal

how is blood pressure for early decompensated shock?

hypotension

how is pulse quality for early decompensated shock?

weak, poor

what is the CRT for early decompensated shock?

prolonged (2 sec)

what is the mucous membrane color for early decompensated shock?

pale

what is the mentation for early decompensated shock?

obtunded, dull

what is the temperature for early decompensated shock?

hypothermia

what is the blood pressure for late decompensated shock?

severe hypotension

what is the heart rate for late decompensated shock?

bradycardia

what is the pulse quality for late decompensated shock?

absent

what are the mucous membrane color for decompensated shock?

pale grey

what is the mentation for late decompensated shock?

stupor/coma

what is the temperature for late decompensated shock?

hypothermia

what is mucous membrane color in distributive shock?

hyperemic

what is the pulse quality for distributive shock?

bounding

what is the temperature for distributive shock?

hyperthermia

what animal is distributive shock not hyperdynamic?

cats

what does it mean when we describe distributive shock as hyperdynamic?

the heart is pumping a normal or abnormally high volume of blood (high cardiac output), even though the blood vessels are severely dilated and blood pressure is low

how do cats appear in shock?

1. hypotension

2. hypothermia

3. bradycardia

what is the bezol-jarisch reflex?

cardioinhibitory reflex causing a sudden drop in blood pressure and heart rate due to increased parasympathetic activity