Module 4 - Cardiac Output

Question 1

Indicate the main cardiovascular parameters

Answer 1

• Cardiac Output (CO)
• — flow generated by the heart
• Pulmonary Blood Volume (PBV)
• — amount of blood that is in the transpulmonary circulation
• Ejection Fraction (EF)
• — Contractility of the cardiac muscle -> the myocardium
• Myocardial perfusion (MP)
• — cardiac muscle needs oxygen. so how much oxygenated blood does the myocardium receive

Question 2

What is cardiac output?

Answer 2

Flow generated by the ventricles. The ventricles can be seen as a piston pump as it changes it’s volume.

Volume of blood that the let ventricle ejects into the aorta in liters per minute

Question 3

Continuous wave doppler system

Answer 3

Ultrasonic waves are created, send through tissue and vessel, and will then be received by a receiver.

Electromechanical conversions; from an electrical voltage or current to mechanical pressure waves and vice versa.

There is a continuous wave signal over time. It investigates quite a large volume

Question 4

Pulsed wave Doppler systems

Answer 4

A single transducer acts as transmitter and as receiver
Advantage is that after we have transmitted one pulse and we start receiving all the reflections, we can also decide, with a window, the reflected signal, with a so-called gate. We can reconstruct the full velocity profile; which is not possible in the continuous wave

Question 5

How is blood flow measured during ultrasound?

Answer 5

We transmit ultrasound through a vessel, and these cells will reflect and scatter back ultrasound which we receive back at the transducer. The frequency that we receive back, is not exactly the same as the one we used for transmission; there will be a difference and this is given by Doppler shift.

Question 6

Name the continuous infusion methods to calculate cardiac output. And name the bolus injection methods

Answer 6

Continuous infusion
- Warm thermodilution and Fick
Bolus injection
- Cold thermodilution
- Dye dilution
- Lithium dilution

Question 7

Explain dye dilution

Answer 7

Injection with an indicator like lye whose concentration can be detected by a specific sensor. We inject a colored substance whose concentration can be optically measured

Question 8

What is lithium dilution?

Answer 8

Injection into the peripheral vein and detected in the arterial line.
continuous CO measurement based on pressure measurement

Question 9

Compare indicator based without indicator

Answer 9

Without indicator you do not need to inject something into the patients blood stream. When using indicators you also use sensors that either need contact with the indicator, leading to very invasive measurements. It is also possible to use imaging methods so that the sensor is not needed in the same way as the contact sensors which is very invasive.