CPRS 32: Venous Return

Question 1

What are they
Central Venous Pressure
Peripheral Venous Pressure

Answer 1

What are they
Central Venous Pressure: Pressure of Vena Cava at Right Atrium
Peripheral Venous Pressure: Pressure of Peripheral Veins at different tissues

Question 2

Why will reduction in cardiac output lead to increased CVP and PVP

Why will increase in cardiac output lead to decreased CVP and PVP

Answer 2

Why will reduction in cardiac output lead to increased CVP and PVP: Increased blood accumulation in IVC and Right Atrium, plus peripheral veins

Why will increase in cardiac output lead to decreased CVP and PVP: Decreased blood accumulation in IVC and Right Atrium, plus peripheral veins

Question 3

When Cardiac Output is 0, Venous Return is ____

The mean systemic filling pressure is achieved at the pressure when the venous return reaches 0, what is the value?

Answer 3

When Cardiac Output is 0, Venous Return is 0.
The mean systemic filling pressure is achieved at the pressure when the venous return reaches 0, what is the value? 7mmHg

Question 4

Imagine the curve (CPRS 32)
Cardiac output/ Venous return against Central Venous Pressure

When there is positive inotropic agent, how would the graph change

Answer 4

Imagine the curve (CPRS 32)
Cardiac output/ Venous return against Central Venous Pressure

When there is positive inotropic agent, how would the graph change

Venous return unchanged
Cardiac output increases (shift upwards)

Question 5

Imagine the curve (CPRS 32)
Cardiac output/ Venous return against Central Venous Pressure

When there is increased resistance, how would the graph change

Answer 5

Imagine the curve (CPRS 32)
Cardiac output/ Venous return against Central Venous Pressure

When there is increased resistance, how would the graph change

Venous return shift downwards
Cardiac output shifts downwards

Question 6

Imagine the curve (CPRS 32)
Cardiac output/ Venous return against Central Venous Pressure

When there is increased blood volume, how would the graph change

Answer 6

Imagine the curve (CPRS 32)
Cardiac output/ Venous return against Central Venous Pressure

When there is increased blood volume, how would the graph change

The venous return shifts upwards

Question 7

Imagine the curve (CPRS 32)
Cardiac output/ Venous return against Central Venous Pressure

When there is decreased vein compliance, how would the graph change

Answer 7

Imagine the curve (CPRS 32)
Cardiac output/ Venous return against Central Venous Pressure

When there is decreased vein compliance, how would the graph change

Decrease vein compliance
Increase vein elasticity
Less blood accumulation
Blood will flow faster to the atrium
VENOUS RETURN GRAPH SHIFTS UPWARDS

Question 8

Which position has a higher venous return?
Standing or supine
Why

Answer 8

Supine

Gravitational force during standing causes blood to accumulate at the lower limbs

Question 9

What is meant by orthostatic hypotension

Answer 9

a 20mmHg drop in systolic pressure
a 10mmHg drop in diastolic pressure
within 3 mins of standing

Question 10

What other factors will increase the venous return, name the details of the following

• Muscle pump
• Intra-abdominal pressure

Answer 10

What other factors will increase the venous return, name the details of the following

• Muscle pump: More frequent muscle contraction will lead to higher venous return
• Intra-abdominal pressure: When IVC are compressed by organs inside the abdomen, will cause increase in venous return

Question 11

Which of the following will change when we change from supine to upright position?

• Venous return
• Stroke Volume
• Heart Rate
• Cardiac Output
• Total peripheral resistance

Answer 11

Which of the following will change when we change from supine to upright position?

• Venous return: Decrease
• Stroke Volume: Decrease
• Heart Rate: Unchanged or slight increase
• Cardiac Output: Decrease
• Total peripheral resistance: Unchanged or slight increase

Question 12

Systolic pressure increases when _______ increases

Diastolic pressure increases when ________ increases

Answer 12

Systolic pressure increases when stroke volume increases

Diastolic pressure increases when total peripheral resistance increases

Question 13

How will respiratory activity affect venous return TO THE RIGHT HEART
For inspiration, the intrapleural pressure will become more ___________.
The IVC and SVC ‘_________’ which ______ the blood flow and preload.

Answer 13

How will respiratory activity affect venous return TO THE RIGHT HEART
For inspiration, the intrapleural pressure will become more negative.
The IVC and SVC ‘expands’ which increase the blood flow and preload

Question 14

How would tension pneumothorax cause changes in the venous return?

It increase the ___________ pressure
A positive intrapleural pressure will compress the ________ and ______, this will __________ the venous return

Answer 14

How would tension pneumothorax cause changes in the venous return?

It increase the intrapleural pressure
A positive intrapleural pressure will compress the SVC and IVC, this will decrease the venous return

Question 15

Varicose veins will _______ the venous return

Answer 15

Varicose veins will decrease the venous return

Question 16

How would the respiratory activity affect the left heart filling

During Inspiration, the left atrium and left ventricle _________. This leads to the lungs and pulmonary vessels _________. This will lead to ______ blood being held in the pulmonary circulation. This will lead to __________ preload of Left atrium and left ventricle, _____ the left heart filling.

During expiration, the lung __________. ______ blood flows from pulmonary circulation to left atrium. This _________ the preload and leads to _________ left heart filling.

Answer 16

How would the respiratory activity affect the left heart filling

During Inspiration, the left atrium and left ventricle expands. This leads to the lungs and pulmonary vessels being expanded. This will lead to more blood being held in the pulmonary circulation. This will lead to decreased preload of Left atrium and left ventricle, reducing the left heart filling.

During expiration, the lung deflates. More blood flows from pulmonary circulation to left atrium. This increases the preload and leads to increased left heart filling.