Shock & Systemic Response to Injury Flashcards
What is a simple definition of shock?
Cardiovascular collapse
What are the main types of insult or injury?
Trauma, stress, sepsis, GA, Sx
A stress response caused by insult or injury results in
Initiating the sympathoadrenal axis
Leads to release of catecholamines
leads to release of cortisol
What is shock?
Failure of the cardiovascular system to deliver adequate oxygen & nutrients to tissues
Tissue perfusion is dependent on:
circulating blood/fluids
heart pump ability
vagal motor tone
vascular musculature
What are the main classifications of shock?
Cardiogenic
Hypovolaemic
Distributive/Vasogenic
(Obstructive)
What is cardiogenic shock?
Failure of the heart, so unable to push blood around the body
What is hypovolaemic shock?
Volume deficit preventing deliver of oxygen and nutrients to the body
In hypovolaemic shock, a reduction of circulating volume is caused by…
whole blood loss
fluid loss (dehydration)
intestinal hypersecretion
What is distributive/vasogenic shock?
Blood maldistribution where the volume is available within the body but cannot be distributed to the appropriate location (vascular tone issues)
Describe the path of Vasogenic/Distributive shock.
Entotoxemia/sepsis/anaphylaxis –> release of vasoactive substances –> extensive dilation –> pooling of blood –> massive maldistribution of blood volume
Septic causes of Vasogenic/distributive shock can lead to what syndrome?
Systemic inflammatory response syndrome (SIRS)
What are the 3 main causes of vasogenic/distributive shock?
Sepsis, anaphylaxis, neurogenic
What are the main characteristics of the early or acute phase of shock?
conservation of fluid volume
change in energy metabolism
accelerated metabolic rate
What changes within the body will be seen during the early or acute phase of shock?
Increased HR
Increased SV
Increased peripheral pulses
Increased CRT
How does the body respond to the early/acute phase of shock?
increases sympathetic tone to conserve and minimize any losses –> vasoconstriction peripherally; increase HR/SV so the heart works harder increasing cardiac output; chemoreceptors tell the body to reduce oxygen saturation so the kidney stops secretion to conserve
What main organs/tissues are affected by the early/acute phase of shock?
kidneys, heart, blood vessels
What occurs during the decompensatory phase of shock?
Insult to the body continues and the compensatory mechanisms are unable to keep up. This leads to breakdown of the gut wall, increasing toxins, and thus overwhelming the liver. The liver releases more inflammatory mediators causing autoregulatory escape. This leads to organ vasodilation, blood pooling, further maldistribution, release of more cytokines from hypoxic tissues, DIC initiated, multiple organ failure, then death.
What clinical signs can be seen in the compensatory phase of shock?
tachycardia, tachypnoea, hyperaemic MM, fast CRT, increased peripheral pulses
What clinical signs can be seen in early decompensatory phase?
progressive tachycardia, tachypnoea, prolonged CRT, cold extremities, weak peripheral pulses, anuria/oliguria, depression, lack of responsiveness
What clinical signs can be seen in the late decompensatory phase?
Hypotension, bradycardia, circulatory collapse, pale MM, anuria, collapse, severe depression
Also possible: recumbency, loss of consciousness
What are the main ways of treating shock?
Oxygen supplementation
Restoration of circulating volume through early aggressive fluid therapy
Glucocorticosteroids
Pain control
Cardiovascular support
Control of haemorrhage
What are some things to ask yourself when thinking of fluid therapy?
Crystalloid vs colloid?
Isotonic vs hypertonic?
Plasma/whole blood?
Synthetic blood products?
What is the shock dose rate of administration of crystalloid fluids?
90 ml/kg/hr
what is the normal maintenance dose of crystalloid fluids?
2.5 ml/kg/hr
When giving fluid therapy, if there is a lack of control of hypotension due to ongoing haemorrhage, what can happen in the body and how can it be prevented?
Excess amounts of fluid therapy can dislodge clots
Prevention by giving less fluids to maintain a lower BP to prevent dislodging clots
What do you monitor to determine the effectiveness of your fluid therapy?
cardiac output and perfusion
What are signs of improvement in a shock patient following fluid therapy?
increased HR
increased BP
Improved mentation
Warming of extremities
decreased CRT
increased urine production
return to normal serum lactate levels
What are the phases of injury?
Acute phase
Flow/Catabolic Phase
Recovery/Anabolic Phase
Describe your process when receiving a patient showing signs of the acute phase of injury.
- evaluate the animal
- recognize the signs of shock
- Full clinical exam, catalogue all injuries
How do you minimize the length and severity of the acute phase of injury?
minimize further tissue trauma
restore circulating volume
reduce bacterial contamination
maintain body temperature
careful hemostasis
adequate immobilization & analgesia
Provision of adequate dietary intake
minimize stress thru appropriate handling & husbandry
restrict exercise
control any infection
The prolonged stress response of the acute phase of injury induces…
the hypermetabolic state
During the Catabolic phase, what occurs?
Total body catabolism raises leading to increased nutritional demands. This leads to persistent hyperglycaemia and rapid muscle and fat breakdown leading to weight loss, thus prolonging tissue healing
What is the third phase of injury called?
the Anabolic or recovery phase
What occurs during the recovery/anabolic phase of injury?
Any losses from the acute phase are replaced. The systemic neurohormonal system returns to normal, thus stabilizing catecholamine and cortisol levels. Visceral and muscle protein is synthesized, organ function improves. Appetite increases, animal gains weight, strength and vitality improve.
