Shock

Question 1

What is a shock?

Answer 1

It’s an abnormality of the circulation that causes inadequate organ perfusion and oxygenation.

Question 2

How does normal regulation of tissue perfusion occurs?

Answer 2

The autonomic nervous system is able to alter:
- Heart rate
- peripheral vascular resistance.
In response to changes in blood pressure detected by:
- Carotid sinus.
- Aortic arch baroreceptors.

Changes in the systemic vascular resistance may alter venous return by changing the amount of fluid circulating in the cutaneous and splanchnic vascular bed.

Also, the kidney regulates volume by the regulation of Na loss by the Renin-Angiotensin-Aldosterone System (RAAS) and Antidiuretic hormone, which controls water loss in the renal tubules and collecting ducts.

Fall in circulating volume prompts the sensation of thirst, stimulating increased fluid intake.

Question 3

What are the classes of shock?

Answer 3

1. Cardiogenic shock.
2. Obstructive shock
3. Distributive shock
4. Hypovolemic shock.

Question 4

What are the causes of cardiogenic shock?

Answer 4

• Massive myocardial infarction.
• Mitral or aortic valve rupture.
• Acute ventriculoseptal defect.
• Cardiomyopathy and viral myocarditis.

Question 5

What is the definition of cardiogenic shock?

Answer 5

A primary failure of cardiac output in which the heart is unable to maintain adequate stroke volume in spite of satisfactory filling.

Question 6

What are the causes of obstructive shock?

Answer 6

• Pulmonary embolism.
• Tension pneumpthorax.
• Acute cardiac tamponade.

Question 7

What is the definition of obstructive shock?

Answer 7

Obstruction to outflow. OR,
intravascular obstruction, excessive stiffness of arterial walls and microvascular blockage places an undue stress on the heart.

Question 8

What is the definition of Hypovolemic shock?

Answer 8

Decresaed circulating blood volume.

Question 9

What are the causes of hypovolemic shock?

Answer 9

• Hemorrhage.
• Dehydration.
• Burns.

Question 10

What are the causes of distributive shock?

Answer 10

• Sepsis
• Anaphylaxis
• Spinal shock.

Question 11

What are the features of hypoperfusion ?

Answer 11

• Confusion or coma due to cerebral hypoperfusion.
• cardiac failure and arrest due to coronary hypoperfusion
• Pallor, cold and clammy skin due to cutaneous hypoperfusion.
• Oliguria/anuria due to renal hypoperfusion.
• hypoxia, pulmonary edema due to lung hypoperfusion.
• Raised lactate.

Question 12

What is a Swan- Ganz catheter ?

Answer 12

This is a multiple lumen catheter that is inserted through the subclavian or Internal jugular vein into the right atrium in the heart which measures the centeral venous pressure, cardiac output and core temperature.

Question 13

What are the actions of Dopamine?

Answer 13

depends on the dose:

• Low dose: 2 microgram/kg/min : increase renal perfusion.
• moderate dose: 5 micrograms/kg/min: Beta 1 effect with +ve inotropic activity ( increasing myocardial contractility and rate).
• High dose: >5 micrograms/kg/min : alpha effect with vasoconstriction.

Question 14

What is the rule of Dobutamine in shock and in which type of shock is used?

Answer 14

Dobutamine is used in cardiogenic shock. Has beta 1 action. It increases myocardial contractility and rate, thus increasing cardiac output.

Question 15

Adequate blood pressure, depends on what ?

BP =?

Answer 15

Cardiac output and systemic vascular resistence

BP = CO x SVR

Question 16

Cardiac output =

Answer 16

CO = Heart rate x stroke volume.

Question 17

How does the body compensate in cardiogenic shock?

Answer 17

Increase in heart rate and systemic vascular resistance, clinicallly: tachycardia, sweating, pallor and coldness.

Question 18

What do cardiogenic shock and circulatory obstruction characterized by?

Answer 18

raised venous pressure

Question 19

How does Vasovagal syndome occur?

Answer 19

Occur in severe pain or emotional disturbance, the vagus nerve slows the heart and causes vasodilatation .
Hypotension caused by fall in cardiac output due to both bradycardia and reduced venous return.

Question 20

Which type of fluid should be administered in patients with shock and in what rate ?

Answer 20

crystalloid , rapid infusion:

300- 500 mL / 20 mins.

Question 21

How to treat anaphylactic shock ?

Answer 21

• ABC
• Remove source.
• Insert 2 large bore IV lines
• Start crystalloid fluid. (NS).
• Give 1 mL of 1:1000 Adrenaline/epinephrine IM/SubQ (can be repeated Q10 -30 mins PRN).
• Give Chlorpheniramine (antihistamine) 10mg IV
• Give steroids (hydrocortisone) 100 mg IV

Question 22

What is the most important side effect of Adrenaline/ epinephrine?

Answer 22

Powerful vasoconstriction may cause ischemia and infarction to peripheral tissue most commonly to fingers, toes and tips of nose and ears.

Question 23

How to categorize hypovolemic shock depending on the amount lost and the symptoms & signs?

Answer 23

Class1: 
-  < 15% - 750 mL fluid loss.
- minimal symptoms.
Class 2: 
- 15- 30 % - 750 - 1000 mL fluid loss 
- Tachycardia >100
- Tachypnea
- Decreased pulse rate.
- pale , sweaty and cold peripheries.
Class 3: 
- 30 - 40 % - 1500 - 2000 mL fluid loss. 
- Tachycardia > 120 
- Hypotension
- Tachypnea
- Pallor
- cold peripheries.
- Oliguria
- Decreased LOC
Class 4: 
- > 40% - > 2000 mL fluid loss.
- Tachycardia > 140 
- Hypotension
- Pallor &amp; cold peripheries.
- Anuria 
-  Unconscious.

Question 24

From where does antidiuretic hormones are produced?

Answer 24

Posterior pituitary gland