Flashcards in Review And Shock Deck (27):
How can stress tests be carried out?
Pharmacological (beta adrenoceptor agonist)
Why might some patients not experience pain in MI?
Diabetic patients - neuropathy
Describe the progression of ECG changes in a STEMI
First change = ST elevation
After a few hours = decreased height of R wave and pathological Q waves form
After 1-2 days = T wave inversion
Weeks later = everything may normalise except pathological Q waves remain
Describe cardiac arrest
Unresponsiveness associated with lack of pulse
Heart has stopped or has ceased to pump effectively
What are the 3 types of cardiac arrest?
Asystole (loss of electrical and mechanical activity)
Pulseless electrical activity (no link between electrical and mechanical)
Ventricular fibrillation (uncoordinated electrical)
What 3 things commonly lead to VF?
How does defibrillation work?
Depolarises all the cells to put them in the refractory period
Allows coordinated electrical activity to restart
What is haemodynamic shock?
Acute condition of inadequate blood flow throughout the body with a catastrophic fall in arterial BP
What is the BP equation?
BP = CO x TPR
What 2 things can cause shock?
Fall in cardiac output
Fall in TPR
What is cardiogenic shock?
Ventricle cannot empty properly
What is mechanical shock?
Ventricle cannot fill properly
Decrease output (Starling's law)
What is hypovolaemic shock?
Reduced blood volume
Poor venous return
Name 3 causes of cardiogenic shock
Acute worsening of HF
What is the equation for CO?
CO = HR x SV
What are the 2 main causes of mechanical shock?
What percentage of blood has to be lost to show signs of shock?
20-30% some signs of shock
30-40% serious shock response
What is the compensatory response due to haemorrhage?
Arterial BP fall detected by baroreceptors
Increase SNS output
Tachycardia, increase force of contraction and cause venoconstriction and vasoconstriction
How would a patient with hypovolaemic shock present?
Cold, clammy extremities
Other than haemorrhage, what else can cause hypovolemic shock?
Severe diarrhoea/voting (loss of Na+)
What is the danger of hypovolemic shock?
The vasoconstriction causes impaired tissue person therefore the tissue releases chemical mediators to cause vasodilation
TPR falls - BP falls
Can lead to multi system failure
What is distributive shock?
Low resistance - vasodilation causing a decrease TPR
Toxic or anaphylactic
What causes vasodilation in anaphylaxis?
Severe allergic reaction causing histamine to be released from mast cells - decrease TPR
Chemical mediators in anaphylactic shock also cause ...
How does a patient with anaphylactic shock present?
Red, warm extremities
What do you give as treatment in anaphylaxis?
Adrenaline - to cause vasoconstriction