fys4250fysisk institutt - rikshospitalet....and slicky tricks to prepare you for the exam

FYS4250 Fysisk institutt - Rikshospitalet

....and slicky tricks to prepare you for the exam...

What is a typical question?

For example:

1. Mention some different methods for measuring blood pressure, explain the different advantages, disadvantages and eventual risks associated with each method

2. Blood flow is another interesting parameter. Describe how it is possible to measure the blood flow both invasive and non-invasively and explain the advantages, disadvantages for each method. What would be the proper requirements for an amplifier in such a measurement system?

3. Do you know any non-invasive methods of measuring the oxygen concentration in the blood? Give a brief description of the manner of operation, sources of error and advantages/disadvantages

4. Give a short explanation of the function of the human heart. How is it possible to detect patology in the heart function without entering the body?

Image: Grimnes, Høgetveit. Biomedical Engineering Education & Advanced Bioengineering Learning: Interdisciplinary Concepts.

”A sensor is a mediator able to convert one or more measurands or physical variables into an equivalent signal variable of another type of quantity within a frame of a given unity”

Pallàs-Areny, Webster, Sensors 2001

What is a sensor?

QuickTime™ og en-dekomprimerer

kreves for å se dette bildet.

Image: Grimnes-Høgetveit. Biomedical Engineering Education & Advanced Bioengineering Learning: Interdisciplinary Concepts.

- Sensor system: ”comprises the total signal path from the measurand to the observer and includes all sensing, conditioning and real-time processing elements in the path”

- Electrode: ” An electrode is an electrochemical cell converting charge carriers from ions to electrons or vice versa. An electrode is only a half-sensor in the way that two electrodes are necessary in order to apply a current or read a potential difference in living tissue”

- Probe: A ”probe is a broader concept than a sensor. A probe is often comprising multiparameter sensors (e.g. temperature) and may be held by the operator and be equipped with switches and level adjustment facilities. Example: Ultrasound probe”

Source: Grimnes-Høgetveit. Biomedical Engineering Education & Advanced Bioengineering Learning: Interdisciplinary Concepts.

More definitions....

Pressure transducerand Wheatstone bridge

Image: Grimnes-Høgetveit. Biomedical Engineering Education & Advanced Bioengineering Learning: Interdisciplinary Concepts.


Piezoelectric

transducer

C=εA/x


Photomultipliers

Membrane potential

Nernst equation for potassium K (Nor - Kalium):

][][

][log5.61

][

][ln 10 mV

K

K

K

K

nF

RTE

i

o

i

oK ==

across a cell membrane with active channels pumping K ions into the cell.

Dipolesin theaxon

Neural velocity

The heart

Atrioventricular-block

Ectopic beat

Tachycardiaflutter=

increased regular

frequency

flimmer (norsk) =fibrillation (eng) =

= uregelmessig rytme

Ischemia

Metal /electrolyte

=electron /

iontransitions

Ag / AgCl Non-polarizable electrode

Electrode polarization +

skin + deeper layer

Stimulation electrodes


Einthoven triangle


Wilson central terminal


Augmented leads


”Driven right leg”


Biopotentail amplifiers


The circulatorysystem


Typical blood pressures


Invasive blood pressure measurement


Harmonic analysis, Fourier


Heart sounds


Stethoscopes, spektrogram


Non-invasive blood pressure


Ultrasound measurement


Bloodpressure, oscillometric


Non-contact tonometry

Indicator-dilution method

∫=

1

0

)(t

dttC

mF

Elektromagnetic flowmeter

BLue=

Electromagnetic flowmeter waveforms

Quadrature-suppression flowm.

Plethysmography

Plethysmography curve

Figure 1 Airways with

larynx, trachea, bronchi and

alveoles

Figure 2

Lung volume parameters

Equation 1 Compliance C = ΔV / ΔP [L/Pa, L/cmH2O]

Equation 2 Poiseuille4

8

r

LR

πη

= [Pa/m3/s = pressure / flow rate]

Figure 6

Laplace cylinder model

P=T/r

Figure 10

Rebreathing circle

with one-directional valves 1 and 2

Figure 13 IR absorption spectra for some anaesthetic agent vapours.

Datex Ohmeda Division, Instrumentarium Corporation

Figure 14 Multigas spectrophotometric gas analyzer

with rotating filter wheel

pH-measurement

pCO2 (Severinghaus) electrode

pO2 (Clark) electrode

Fluorescent dye sensor

pH-sensitive dyes

Pulsoxymetry light absorption

fys4250fysisk institutt - rikshospitalet....and slicky tricks to prepare you for the exam

Documents

interdisciplinary concepts

sensor system

path electrode

electrochemical cell

cell membrane

different advantages

different methods

blood pressure