6.4 Post-Reading and Exercises

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28. What is the strategy to synchronise automatically the signals by means of a pro-

gram?

29. What are the problems if you want to assess the movement of a patient?

Signals of the Cardiovascular System

1.

What diseases can be read from a patient’s ECG?

2.

Why does the inference from the signal to the disease of the heart work?

3.

In what order of magnitude are the measured potentials of the ECG?

4.

What are the physiological causes of the first and second heart sounds?

5.

At what times in relation to the ECG signal do the first and second heart sounds

occur?

6.

How does the phonocardiogram change under severe physical stress compared to

that at rest?

7.

Why is the phonocardiogram broken down into different frequency bands? What

diagnostic information can be obtained from it?

8.

What is meant by the abbreviation 2L2 in relation to a phonocardiogram?

9.

At what times in relation to the ECG signal do the first and second heart sounds

occur?

10. What is the relationship between the "LVET" parameter and the phonocardio-

gram?

11. Why is autocorrelation used for the automatic determination of LVET?

12. How can the LVET be read from the result of the autocorrelation?

13. What is the frequency relationship of a phonocardiogram and the sounds of mech-

anical prosthetic heart valves?

14. Name two objectives of a photoplethysmogram. What parameters can be ob-

tained?

15. On which physical properties of blood is the SpO2 measurement based? How can

these be measured?

16. Describe the respiration process down to the cells. What effects play a role there?

17.

What is meant by an absorption spectrum? What quantities are needed to describe

absorption?

18. What does the Lambert-Beer law say?

19. Why do you need two wavelengths for the determination of SpO2?

20. Why is one time point not sufficient to determine the SpO2 value?

21. Describe the technical construction of a pulse oximeter.

22. Describe the signal-processing structure of a pulse oximeter based on its compon-

ents.

23. Which component is used to use a common photodetector for both LEDs? What

other signal processing steps does this require?

24. Why do you pulse the two LEDs?

25. In which range do you use pulse oximeters?