WK 6- Shock Flashcards
What is the definition of shock
-Inadequate perfusion of vital organs (heart/brain/kidneys)- global hypoperfusion
What is the cause of septic shock
Immune response is triggered from breakdown of bacterial cell wall which releases endotoxins→ causes cytokine storm→ increased capillary permeability/low BP/clotting abnormalities
-can be caused by Gram negative sepsis, GIT or Pelvic infection, Meningococcus, Meliodosis
What is the definition of anaphylactic shock
Acute allergic reaction due to extreme mast cell degranulation (resulting from prior exposure and cross bridging of IgE) causing symptoms such as urticarial rash, hypotension, bronchospasm and oedema, tachycardia, GI symptoms (vomiting, diarrhoea)
What are the causes of mechanical shock
Tamponade-> built up fluid and pressure on the heart causes decrease in cardiac contractility
-Pneumothorax-> build up or pressure between the pleura and the lungs, compressing the lungs, shifting the mediastinum and occluding the vena cava
What is the cause of hypovolemic shock
- Can be due to haemorrhage→ internal haemorrhage (ectopic, spleen, trauma, bleeding from internal organ) or external (obstetric, trauma, GIT-ie. Bleeding ulcer)
- can also be due to fluid loss (vomiting/diarrhoea), metabolic causes (diabetes) or burns/heat stroke
- all contribute to low blood volume
What is the cause of neurogenic shock
- if damage is above T4, there will be loss of autonomic supply to the heart and causes no vasoconstriction→ causes hypotension, bradycardia
- Treatment: stabilise and give fluids
What is the grading of haemarrohage
- if pulse and BP is normal= grade 1
- tachy and normal bp= grade 2
- tachy and slightly hypotensive (80/60)= grade 3
- tachy and unrecordable bp (ie. 60/40)= grade 4
What are the signs of decreased myocardial perfusion
ischemia, hypertension→ third sign of shock→ never normally vasoconstrict coronary arteries, so if the heart has decreased myocardial perfusion (bradycardic and saggy ST waves) the patient is dying
-end stage shock
What differentiates between septic and hypovolemic shock
-main difference between hypovolvemic and septic shock is the abnormalities in temperature→ hypothermic or hyperthermic- hypothermic is more severe→ means they have gone past the inflammatory stage with fever
What is distributive shock
results from excessive vasodilation and the impaired distribution of blood flow–> capillaries leak and cause oedema
What is the treatment for anaphylactic shock
Airway, breathing, circulation
- Give Adrenaline 0.5 mg IM
- Adrenaline 5 mg nebulised
- IV infusion titrated to effect- 1mg/1L of saline= 1mcg/ml→ more effective
What is the treatment for septic shock
Need to recognise and treat early→ with antibiotics, but if they’ve also got purulent abscess that has caused their septic shock→ need surgery urgently
- Give IV fluids
- Early broad spectrum antibiotics (IV piptaz)
- Inotropic Support
- Improve myocardial perfusion
What causes cardiogenic shock
-Caused by AMI, Valvular problems, Cardiomyopathy, Myocarditis
What is the tx for cardiogenic shock
monitoring, angioplasty, inotropes, balloon pump, transplant→ even with this, the heart is weak and the pt will not fully recover
-angioplasty/bypass can aid with reperfusion
How much blood is lost in grade 1 haemorrhage
less than 15% total blood volume
-less than 750ml
How much blood is lost in grade 2 haemorrhage
15-30% of total blood volume
-less than 1.5L
How much blood is lost in grade 3 haemorrhage
30-40% of total blood
-less than 2L
How much blood is lost in grade 4 haemorrhage
40% of total blood
-more than 2L
Why does glucose have no use as a resus drug
largely taken up by cells (large volume of distribution)- none will stay in blood
Why are colloid drugs effective in resus
-colloid particles are large particles
kept in blood by caplllary membrane→ but can cause side effects (anaphylaxis) and as effective as saline→ just have to give 4x as much saline as colloid
Why are crystalloid drugs effective in resus
Na Cl (sodium chloride) kept in ECF by Na K ATPase--> increasing ECF volume →Vd 14 l, 25% remains in circulation (3.5l)
What fluid would be given to people who are bleeding out
BLOOD
-if you suspect shock, immediately put in two large bore IV cannulas, and get blood type so that blood products can be given quickly
How many litres of plasma are in the body
2.5L
How many litres of RBC are in the body
1.5L
How many litres of intracellular fluid are in the body
28L
How many litres of extracellular fluid are in the body
14L
If a pt presents drowsy, pale, ashen or unconscious, what grade haemorrhage would they have
grade 4 haemorrhage
If a pt presents agitated and lethargic, what grade haemorrhage would they have
3
What is the cardiac reserve
This helps determine the likelihood of you being able to tolerate a given disease or injury. The more cardiac reserve you have the less likely you will become shocked after losing ‘x’ amount of blood. The less cardiac reserve you have the more likely you will become shocked.
What decreases your cardiac reserve
those with severe coronary thrombosis have decreased cardiac reserve- risk factors for coronary thrombosis include smoking, lack of exercise, being severely overweight→ therefore homer would have the least cardiac reserve
How does a pneumothorax cause shock
If the pneumothorax is very large, and under tension, it may cause shift of the mediastinum→ cases compression of the vena cava→ causing decreased blood return to the heart resulting in decreased cardiac output and decreased perfusion
How do people compensate to maintain cardiac output
- release of renin, angiotensin, and aldosterone
-increase in heart rate and contractility - release of erythropoietin to stimulate
RBC increase
What is stroke volume
amount of blood being pumped from the left ventricle per contraction
What is EDV
end diastolic volume= is the volume of blood in the right and/or left ventricle at end load or filling in (diastole) or the amount of blood in the ventricles just before systole.
What is ESV
end systolic volume=volume of blood in a ventricle at the end of contraction, or systole, and the beginning of filling, or diastole
If a heart is not pumping properly (decreased contractility) which direction will his Starling curve move ?
downwards and to the right due to extreme heart failure
What is starlings law
the greater amount of blood volume (preload)
into the ventricle of the heart during diastole (the relaxed phase) the greater the amount of blood volume ejected out of the heart during the systolic(contraction phase)
–> greater the preload, greater the cardiac output
Describe the Renin-Angiotensin- Aldosterone pathway and the response of this pathway to hypovolaemia
- Liver → increased angiotensinogen
- kidneys → increased renin → increased angiotensin I (+ ACE) → increased angiotensin II → arterial vasoconstriction→ increased BP
- adrenal cortex → increased aldosterone → increased Na and water reabsorption by kidneys → increased BV → increased BP
Describe the Renin-Angiotensin- Aldosterone pathway and the response of this pathway to hypovolaemia
- Drop in blood pressure
- Stimulates renin release from the kidneys and angiotensin release form the liver–> renin converts angiotensinogen to angiotensin 1
- Lungs release ACE-> converts angiotensin 1 to angiotensin 2
- Angiotensin 2 stimulates vasoconstriction and stimulates adrenal glands to release aldosterone
- Aldosterone stimulates kidneys to reabsorb salt and water
Why are levels of acidosis checked in shock
- assess the degree of hypoperfusion
- lactic acidosis is a form of metabolic acidosis due to the inadequate clearance of lactic acid from the blood. Lactate is a byproduct of anaerobic respiration and is normally cleared from the blood by the liver, kidney and skeletal muscle→ normally removed by buffer system
How does Starlings law relate to cardiac output when a patient has cardiogenic shock?
As the myocardium is stretched passed optimum level, the effect of myocardial stretch is diminished so that further stretching does not lead to improvement in contractility
