Shock Flashcards
What is shock?
Clinical state of cardiovascular collapse characterized by the inadequate perfusion of the cells and tissues resulting in hypotension and cellular hypoxia and if uncompensated, may lead to impaired cellular metabolism and death.
What are the stages of shock?
- Initial stage
- tissues are under perfused, decreased oxygen, increased anaerobic metabolism, lactic acid is building - Compensatory stage
- reversible
- attempting to compensate for the decrease tissue perfusion
- neuroendocrine, hematology, CVS, renal - Progressive stage
- failing compensatory mechanisms
- profound vasoconstriction
- lactic acid production is high - metabolic acidosis - Irreversible or refractory stage
- cellular necrosis
- multiple organ dysfunction syndrome may occur
What are the types of shock?
- Hypovolemic shock
- blood volume problem - Cardiogenic shock
- blood pump problem - Distributive shock
- blood vessel problem
- septic, anaphylatic and neurogenic
What is hypovolemic shock?
Medical or surgical condition in which rapid blood or fluid loss results in multiple organ failure due to inadequate circulating volume and subsequent inadequate perfusion
What are the causes of hypovolemic shock?
- Blood loss
- traumatic injury (blunt trauma)
- vascular disorders (e.g. aneurysms, dissections, arteriovenous malformations)
- GI disorders
- pregnancy-related disorders - Fluid loss
- refractory gastroenteritis
- extensive burns
What is the pathophysiology of hypovolemic shock?
low venous return > low preload > low CO > hypotension > perfusion failure & tissue hypoxia > organ dysfunction > multiorgan failure
Compensatory mechanism mostly occurs during what type of shock?
Hypovolemic shock
What are the four components that make up the compensatory mechanism?
- Hematology system
- Cardiovascular system
- Renal system
- Neuroendocrine system
Describe the hematology system of compensatory mechanism
- Activates the coagulation system and contracting bleeding vessels (thromboxane A2)
- Immature clot that is not stable will form on the bleeding source
- Fibrin deposition occur due to exposed collagen (due to damaged vessels) to stabilize the immature clot and stop from bleeding
Describe the cardiovascular system in compensatory mechanism
- Increased release of norepinephrine & decreased baseline vagal tone to increase heart rate, myocardial contractility & constrict peripheral blood vessels
- This will increase the volume in the blood vessels
- Redistribution of blood to vital organs like brain, heart & kidney (away from skin, muscle & GI tract)
Describe the renal system in compensatory mechanism
- Stimulating an increase in renin-angiotensin-aldosterone system due to reduced volume in kidney
- Angiotensin II - to vasoconstrict arteriolar smooth muscle and aldosterone secretion by adrenal cortex
- Aldosterone - responsible for active sodium reabsorption and water conservation (to reduce water secretion in kidney and maintain/increase volume in vessels)
Describe the neuroendocrine system in compensatory mechanism
- Increase in circulating ADH by posterior pituitary gland
- In response to decrease in BP & decrease in sodium concentration
- ADH - will increase water reabsorption of water and salt by distal tubule, collecting duct and loop of Henle
What is the principle management of hypovolemic shock
To restore circulating volume, tissue perfusion and correct cause
What is the management of hypovolemic shock in emergency department care
- Maximize oxygen delivery
- Control further blood loss
- Fluid resuscitation
- Medication e.g. Somatostatin (have vasoconstrictive properties & can reduce blood flow to portal systems)
What is the definition of cardiogenic shock
Decreased CO due to cardiac dysfunction and evidence of tissue hypoxia in the presence of adequate intravascular volume (normal volume)