12. Shock Flashcards
Define shock
An acute condition of inadequate blood flow throughout the body
What is mean arterial pressure equal to?
CO x TPR
Name 3 causes of cardiogenic shock
Following MI due to left ventricle damage
Serious arrhythmias
Acute worsening of heart failiure
What happens in cardiogenic shock?
Heart fills but fails to pump effectively
Central venous pressure rises
Arterial pressure falls
Tissues are poorly perfused (coronary arteries included which exacerbates the situation)
Name 2 causes of mechanical shock
Cardiac tamponade
Massive pulmonary embolism
What happens in shock caused by cardiac tamponade?
Filling is restricted, end diastolic volume is much smaller
Increase in venous pressure
Decrease in arterial pressure
What happens in shock caused by massive pulmonary embolism?
Embolus occludes large pulmonary artery Pulmonary artery pressure increases Right ventricle cannot empty Venous pressure rises Reduced blood return to left side of heart (left atrial pressure is low) Arterial pressure is low
What percentage of blood must be lost to go into hypovolaemic shock?
30-40%
What will a patient in hypovolaemic shock present with?
Tachycardia
Weak pulse
Pale skin
Cold and clammy extremities
What happens in toxic shock?
Endotoxins released from bacteria lead to:
Vasodilation (decreased TPR), decreased arterial pressure
Impaired perfusion of vital organs
Capillaries are leaky hence blood volume and venous pressure decrease
The fall in arterial pressure is detected and cardiac output increased
How does a patient in toxic shock present?
Tachycardia
Warm and red extremities
What happens in anaphylactic shock?
Severe allergic reaction Release of histamine from mast cells Drop in TPR and arterial pressure Sympathetic response increases cardiac output Impaired perfusion of vital organs Bronchoconstriction and laryngeal oedema
How will a patient with anaphylactic shock present and how do you treat them?
Difficulty breathing
Rapid heart rate
Red and warm extremities
Treat with adrenaline
