Surgery 2.1 (1-3) Flashcards
Define “shock”
Inadequate delivery of oxygen and nutrients to maintain normal tissue and cellular function
Can shock be fatal?
Yes, if left untreated than shock can be fatal
How quickly should be treated?
Shock must be treated and reconised immediately or the patient may die
Is shock something that can be easily diagnosed by simple conditions?
Shock can be quite complex, for example while low blood pressure and a rapid pulse or cool palmy skin are symptoms - they are NOT the only symptoms
What causes shock?
The inadequate perfusion of of the body’s cells with oxygenated blood
How does the body respond to shock?
The insult, whether hemorrhage, injury or infection initiates both a neuroendocrine and inflammatory mediator response
What are the three phases of shock?
Compensated shock, decompensated shock and irreversible shock
What happens during “compensated shock”?
Vasconstriction, fluid shift to ECF, salt and water conservation by the kidneys
What happens during “decompensated shock”?
With tissue injury ongoing and contined hyperfusion, results cell to death.
Can “decompensated shock” be reversed?
Yes, with proper resuscitation
What happens during “irreversible shock?
Persistant hypoperfusion, fluid resuscitation and vasopressers fail to maintain adequate blood pressure
What are the three manisfestations of shock?
Tachycardia (increased heartbeat), tachypnia (rapid breathing) and pallor (pale skin)
What does the “initial insult” cause?
Whether caused by hemorrhage, injury or infection - the initial insult initiates both neuroendocrine and inflammatory responses like tachycardia, tachypnia and pallor
What is the psychological effect?
The psychological effect is proportional to the degree and length of shock
What causes pale skin (pallor) during shock?
Prompt increase in cardiac contractility and peripheral vascular tone
What is the hormonal responses to salt volume during shock?
Salt is preserved to maintain water
What is the hormonal responses to intravascular volume during shock?
Urine output will be low and increase in urine concentration
What local and microcirculation regions are changed during shock to regulate blood flow?
Skin-stomach-kidney-lungs
What is the goal of the neuroendocrine response during shock?
To maintain perfusion to the heart and brain
What mechanisms are employed during the neuroendocrine response to shock?
Automatic control of peripheral vascular tone and cardiac contractility; hormonal response to stress and volumen depletion and local microregulatory mechanisms that are organ specific and regulate regional blood flow
Where and how are the impulses transmitted during shock to activate the effector response?
The impulses are transmitted from the periphery and processed within the central nervous system
What is the initial inciting event for impulses?
Loss of circulating blood volume
After the initial inciting event, what other stimuli can occur to start impulses during shock?
Pain, hypoxemia, hypercarbia, acidosis, infection, changes in temperature, emotional arousal and hyperglycemia
Define “hypoxemia”
Low oxygen of organs and tissues in the body
What are “baroreceptors”?
Volumne receptors within atria (RA) of the heart aortic arch and carotid bodies (normally inhibit induction of ANS)
What happens with baroreceptors are “activated”?
Their outpout is diminished (disinhibiting the ANS) which leads to sympathetic activation at the vasomotor centres of the brain
What is the function of the “chemoreceptors”?
To maintain adequate pressure of fluids
Where are the chemoreceptors found?
In the aorta and carotid bodies
What three things are chemoreceptors sensitive to?
Changes in oxygen tensions, H ion concentration and CO2 levels
What does stimulation of the chemoreceptors result to?
Vasodilation of coronery arteries, slowing of the heart, vasoconstriction of the splanchnic and skeletal circulation
What are the four types of protein and non-protein mediators?
Histamine, cytokines, eicosanoids and endothelins
When the protein and non-protein mediators produced?
They aproduced at the site of injury
Is the production of protein and non-protein mediators part of inflammatory
respose?
Yes
What is the relationship between shock and inflammation?
The response of inflammation is parallel to the amount of shock. For example, an increase in severity of inflammation = an increase amount of shock
What is the cardiovasular response to efferent signals?
Increase cardiac rate and contraction
- TACHYCARDIA
- Activation of beta 1 adrenergic receptors
- Venous and arterial vasoconstriction
- Activation of alpha-adrenergic receptors
What effect does the catecholamine release have during shock?
It increase energy supply due to increase workload