Hypovolaemia Pathophysiology

Question 1

What is shock?

Answer 1

A condition consisting of circulatory dysfunction resulting in inadequate delivery of oxygen/nutrients to body organs/tissues/cells

Question 2

How is shock progressive?

Answer 2

Compensated shock leads to decompensated shock which leads to irreversible shock which leads to death

Question 3

Why is shock hard to identify in children?

Answer 3

Children are better at compensating for shock

Question 4

What is compensated shock?

Answer 4

It is an early phase of shock where compensatory mechanisms maintain vital organ function

Question 5

What are the compensatory mechanisms in shock?

Answer 5

• Sympathetic stimulation increase heart rate, cardiac output, vasoconstriction and blood pressure. Vasoconstriction diverts blood away from non-essential tissues
• Low blood pressure and cardiac output caused by shock causes secretion of Anti-Diuretic Hormone and Aldosterone reduce water and sodium excretion to maintain blood volume
• Respiratory compensation to compensate for metabolic acidosis caused by anaerobic metabolism

Question 6

What is uncompensated shock?

Answer 6

• Poorly perfused tissues can no longer maintain aerobic metabolism and switch to anaerobic metabolism
• Anaerobic metabolism produces lactic acid and carbonic acid increases due to ineffective CO2 removal
• Acidosis causes damage to capillaries causing them to become permeable and leak fluid from vascular space into tissues, causing oedema, decreased cardiac output and low blood pressure
• Low blood pH (acidosis) reduces the blood’s oxygen carrying capacity/ability
• Anaerobic metabolism and increased use of Adenosine Triphosphate (ATP) causes inability to maintain electrochemical gradient and causes electrolyte dysfunction, impairing the sodium potassium pump, impairing cardiac and CNS function

Question 7

Overall, what does the pathophysiology of hypovolaemia cause?

Answer 7

• Decreased intravascular volume
• Decreased cardiac output
• Hypotension

Question 8

What are the characteristics of hypovolaemia?

Answer 8

Low blood pressure
Poor CRT
Peripheral vasoconstriction
High heart rate

Question 9

What causes impaired cellular metabolism?

Answer 9

• Decreased oxygen and nutrient delivery
• Increased oxygen and nutrient demand
• Decreased removal of cellular waste

Question 10

What airway and breathing symptoms may you expect to see in a hypovolaemic patient?

Answer 10

Tachypnoea, increased depth of breathing, increased respiratory effort, pallor, desaturations, cyanosis

Question 11

What circulatory symptoms may you expect to see in a hypovolaemic patient?

Answer 11

Tachycardia, hypotension, poor perfusion, mottled, weak pulse volume, cold to touch, normal temperature, reduced urine output <1mls/kg

Question 12

What neuological symptoms may you expect to see in a hypovolaemic patient?

Answer 12

Irritability, lethargy, response to voice/pain

Question 13

What exposure symptoms may you expect to see in a hypovolaemic patient?

Answer 13

No rash, bleeding wound

Question 14

What is the treatment for hypovolaemia?

Answer 14

Stop the bleeding, replace fluid losses