SHOCK

What is circulatory shock?

• the sudden failure of blood supply that circulates to the body

What can circulatory shock lead to?

• cellular hypoxia (low cell oxygen)

• organ failure

• death if untreated

What symptoms might a person experience during shock?

• sickness

• weakness

• cold or hot

• dizziness

• confusion

• fear

• thirst

• shortness of breath

What vital sign changes occur during shock?

• hypotension which is blood pressure lower than 60mmHG

• increased respiratory rate

What happens to cells during shock?

• cells switch to anaerobic respiration due to low oxygen

• sodium potassium pumps weaken due to low ATP

What happens when sodium potassium pumps weaken during shock?

• sodium potassium and calcium balances are disrupted

• nerve and muscle function are affected

How can shock worsen over time?

• positive feedback mechanisms

  • these increase the severity of its effects

How does the first positive feedback mechanism worsen shock with fluid shifts?

• sodium enters the cells and makes water follow

• the water will go from the blood vessels to the tissues

  • this reduces blood volume and pressure

• reduced blood volume will lower tissue perfusion which worsens shock

How does the second positive feedback mechanism worsen shock through cell damage?

• low ATP + cell edema damages the cell membranes

  • this releases lysozomal enzymes which damage nearby tissues

• inflammation occurs because of the damage

• the tissue damage will further impair cell metabolism

How does the third positive feedback mechanism worsen shock through oxygen loss and organ damage?

• increased acidity will make hemglobin release oxygen easier

  • poor blood flow still limits oxygen delivery to the tissues

  • so it worsens hypoxia anyway

• this damages organs and can make the shock irreversible

How does cardiogenic shock happen?

• happens when the heart cant pump enough blood even with proper blood volume

• its caused by poor contraction, higher preload, and OR higher afterload

• it most commonly happens after an MI

How does the body respond to cardiogenic shock?

• epinephrine release and RAAS activation because of low blood pressure

• more oxygen demand in the body strains the heart and weakens pumping ability

What is the prognosis of cardiogenic shock?

• its often difficult to treat

• it has a 70% mortality rate

What is hypovolemic shock?

• low blood volume which causes poor circulation

• this is caused by major fluid loss through:

  • bleeding

  • burns

  • diarrhea

  • diureses

When does hypovolemic shock develop?

• it develops when blood volume drops by about 20%

How does the body respond to hypovolemic shock?

• heart rate increases

• vasoconstriction

• fluids will move from the tissues into the blood

• stored blood in the liver and spleen are released

• RAAS and ADH are activated to retain the fluid

What happens if fluid loss continues during hypovolemic shock?

• the compensatory mechanisms eventually fail

• the body wont be able to maintain proper circulation

How do you treat hypovolemic shock?

• replacing blood volume very quickly

• controlling the fluid loss

What is distributive shock?

• vasodilation

• keeps the same blood volume

  • this causes blood pressure to drop

  • low BP reduces blood flow and nutrients to cells

What are the 3 types of distributive shock?

• neurogenic shock

• anaphylactic shock

• septic shock

What happens during neurogenic shock?

• vasodilation caused by:

  • more parasympathetic activity

  • less sympathetic activity

• this type of shock is rare and temporary

What causes neurogenic shock?

• spinal cord or medulla injury

• anesthetic agents

• severe pain

What is anaphylactic shock and what happens during it?

• type 1 hypersensitivity reaction

• it involves mast cells which release histamine and causes:

  • vasodilation

  • increased blood vessel permeability

  • the pooling of blood in peripheral vessels

  • tissue edema

What happens to smooth muscles during anaphylactic shock?

• there is smooth muscle constriction which causes:

  • laryngospasm (throat tightens)

  • bronchospasm (airways narrow)

  • diarrhea

What is the onset and treatment of anaphylactic shock?

• the onset is sudden and can cause a quick death

• is treated with epinephrine

  • causes vasoconstriction

  • will reverse airway constriction

What causes septic shock?

• severe infection triggers a big inflammatory response

• this is caused by microorganisms or their toxins

What is the signifiance of septic shock?

• it is the most common type of distributive shock

• the common cause of death in the ICU

How does septic shock differ from other types of shock?

• it causes warm and flushed skin because of the vasodilation

• other shock types usually cause vasoconstriction instead

What is obstructive shock?

• a blockage that prevents normal blood flow

  • this can affect major veins, the heart, or the lungs

• this increases right heart pressure

• cardiac output is lower beacuse of the blocked blood flow

What are the main causes of obstructive shock?

• pulmonary embolisms which is the most common

• cardiac tamponade which is when fluid compresses the heart

• pneumothorax which is a collapsed lung

What are the main treatments of shock?

• fixing the cause

• IV fluids to increase blood volume

• vasopressors to increase blood pressure

• oxygen