5 - shock & ECG

Question 1

what is shock?

Answer 1

any condition when the blood vessel are not filled and blood cannot circulate normally.

Question 2

what are the 5 different types of shock?

Answer 2

• hypovolemic shock
• vascular shock
• cardiogenic shock
• obstructive shock
• transient vascular shock

Question 3

what causes hypovolemic shock?

Answer 3

rapid drop in blood volume caused by:

• severe vomiting a diarrhoea
• a large scale loss of blood
• severe dehydration

Question 4

what happens to the body during hypovolemic shock?

Answer 4

• intense vasoconstriction: blood is moved from reservoirs to maintain circulation to enhance venous return
• BP stabilises: if loss continues drop in BP means hypovolemic shock
• needs to replace fluid volume ASAP

Question 5

what causes vascular shock?

Answer 5

normal blood volume but poor circulation due to extreme vasodilation resulting in a falling BP

Question 6

what other shocks can vascular shock result in?

Answer 6

• anaphylactic shock (allergen)
• neurogenic shock (sympathetic nerves)
• septic shock (bacterial toxins)

Question 7

what causes cardiogenic shock?

Answer 7

occurs when the heart is so inefficient, usually due to an MI, it cannot sustain circulation

Question 8

what causes obstructive shock?

Answer 8

obstruction to blood flow, most common is pulmonary embolism

Question 9

what causes transient vascular shock?

Answer 9

occurs after sunbathing for too long, blood vessels dilate in the lower limbs

when standing you get pooling of blood in the lower body, drop in BP and giddiness

Question 10

what are the symptoms of shock?

Answer 10

• hypotension - systolic below 90mmHg
• pale skin, moist clammy hands due to vasoconstriction
• confusion and disorientation (due to hypotension, decreased blood flow to heart
• increased heart rate due to sympathetic stimulation
• decreased urine due to hypotension
• thirst
• decreased blood pH (acidosis)

Question 11

what are the 3 stages of shock?

Answer 11

compensated shock - stage I
progressive shock - stage II
irreversible shock - stage III

Question 12

what happens during compensated stage (stage I)

Answer 12

• homeostatic adjustments cope with shock
• vasoconstriction and mobilisation of blood
  reserves to increase blood volume and blood
  pressure
• long term hormonal release of ADH, renin angiotensin aldosterone system & EPO

Question 13

what happens during progressive stage (stage II)

Answer 13

decline in systemic blood pressure, tissue blood flow and cardiac output

Question 14

what happens during irreversible stage (stage III)

Answer 14

rapid decline in cardiac output, irreversible fall in BP, circulatory collapse and death

Question 15

what does an ECG do?

Answer 15

records 12 different views (using 10 electrodes) of the heart and provides a complete “picture” of electrical activity

Question 16

what heart rate is considered to be bradycardia and tachycardia?

Answer 16

bradycardia is <60bpm

tachycardia is >100bpm

Question 17

what causes atrial flutter?

Answer 17

impulses circulate in a localised loop, causing atria to contract at a rapid rate (150-300)bpm

Question 18

what causes atrial fibrillation?

Answer 18

• unsynchronised impulses from multiple ectopic foci in the atria
• atria fibrillate (quiver) and don’t contract properly

Question 19

what causes ventricular tachycardia?

Answer 19

• impulses from an ectopic site in the ventricles promote rapid premature ventricular contractions (>100)

Question 20

what causes ventricular fibrillation?

Answer 20

unsynchronised impulses from multiple ectopic foci in ventricles
- ventricles will fibrillate and don’t contract properly

Question 21

what causes premature ventricular contractions?

Answer 21

• one or more ectopic sites in the ventricles generate an electrical impulse that triggers a premature ventricular contraction

Question 22

what causes conduction disorders?

Answer 22

• caused by alterations in the cardiac conduction pathways
• compression by scar tissue or calcified portions of the heart
• inflammation can depress conductivity from atria to ventricles
• extreme stimulation of the heart by the vagus nerves block impulse conduction

Question 23

what is a first degree block in conduction disorders?

Answer 23

electrical impulses transmission is slowed down between atria and ventricles

Question 24

what is a second degree block in conduction disorders?

Answer 24

atrial depolarisation will sometimes not be strong enough to elicit ventricular depolarisation

Question 25

what is a third degree block in conduction disorders?

Answer 25

electrical signals generated by the SA node aren’t transmitted to the ventricles, atria and ventricles have their own regular and seperate rhythms