Shock Flashcards
definition of shock
A physiological state characterized by a significant, systemic reduction in tissue perfusion, resulting in decreased tissue oxygen delivery and insufficient removal of cellular metabolic products, resulting in tissue injury.
not necessarily decreased perfusion (sometimes perfusion even increases in shock), but definitely decreased O2 delivery
4 things that perfusion requires
- properly beating heart
- adequate transport medium, blood, and hemoglobin
- intact and functioning vessel system
- functioning respiratory system
What does short-term hypoperfusion cause?
long term = shock
Syncope, orthostatic collapse, carotis hyperesthesia, electric shock, spinal cord injury, etc
Perfusion is what?
O2 , nutrient, delivery and CO2 elimination
Normal blood volume
5-6 liters
3 Stages of shock:
- Compensated
- Progressive
- Irreversible
(note that 2 and 3 are normally considered “decompensated” and fall into 3 categories: subacute reversible, subacute irreversible, and acute irreversible.)
What is the final change to note of irreversible shock before cellular death?
Cellular membrane injury
Clinical markers of shock, what are: BP HR Sock Index Resp Rate
BP: systolic <110
Sinus tach, at least > 90 BPM
Sock index: BPsys/pulse < or equal to 1 (normal is 2)
Resp rate: <7 or >29 breaths/min
Clinical markers of shock:
Urine output
Bicarbonate
pO2
Urine output: <0.5mL/kg/hr
Bicarbonate: metabolic acidemia, [HCO3] <31mEq/L or base deficit >3mEq/L
pO2: hypoxemia, depends on age. <80mmHg or <70mmHg
What mental changes are seen as a clinical marker of shock?
Beginnning: Anxiousness, agitation,
End: Indifference, lethary, obtundation
What are the 2 general causes of hypovolemic shock?
Hemorrhage
Dehydration (diarrhea, sweating..)
What are major causes of obstructive shock?
- pulmonary embolism
- tension pneumothorax
- cardiac tamponade
What occurs with cardiogenic shock?
Pump failure. (i.e. 40% of myocardium damaged by AMI)
What does distributive shock mean?
No fluid loss, but it’s being distributed poorly or is not oxygenated. Perfusion is actually increasing, but extreme vasodilation may -> shock.
What may cause and what occurs in neurogenic shock?
Spinal cord injury, drug overdose or poisoning that -> neural deficits -> inability to maintain vascular tone -> vasodilation
Generally, what occurs in anaphylactic shock?
IgE -> Vasodilation and fluid shifting from capillary to the cell. Leads to micro clotting and smooth muscle contraction
What may cause and what occurs in septic shock?
Overwhelming infection -> lot of NO produced + bacterial toxins -> vasodilation and fluid shifting
What may cause urinary tract fluid loss that can cause hypovolemic shock?
Diabetes insipidus or mellitus, salt-wasting disorders, adrenocortical insufficiency, diuretics
What may cause fluid loss from the skin that may cause hypovolemic shock?
Excessive burns, skin inflammation (generalized exfoliative dermititis)
What may cause internal sequestration of fluid that may cause hypovolemic shock?
Loss of volume into interstitial space or body cavities. Chronic liver disease, acute pancreatitis, angioedema
What part of cardiac output is affected by hypovolemia?
Preload is decreased -> CO decreased
How is the body’s response during the compensated stage of hemorrhagic shock?
Volume depletion -> CO decreased -> body detects and increases sympathetic tone -> vasoconstriction + bronchodilation and cardiac stimulation
What happens to the capillary pressure and blood glucose level during compensated hemorrhagic shock?
Capillary pressure decreases, causing interstitial fluid to build up in the vascular compartment
Blood glucose level increases (bc metabolism increases from beta 2 effect), causing osmotic effect that brings fluid to the vascular compartment as well
What are the humoral or delayed responses of compensated hemorrhagic shock?
ADH, aldosterone, renin-angiontensin II
