1. Electromyography (EMG)

2. Electromyogram Electromyograph A tracing made with an electromyograph
Electromyography (EMG) is a medical technique for measuring muscle response to nervous stimulation. An electromyograph detects the electrical potential generated by muscle cells when these cells contract.

3. EMG Signal Characteristics
Signal is generated in the muscle cells
Amplitude range: 50 mV to 30 mV
Frequency range: 7 to 20 Hz depending on the size of the muscle
To perform EMG, a needle electrode is inserted through the skin into the muscle tissue
Because of the needle electrodes, EMG may be somewhat painful or extremely painful to the patient, and the muscle may feel tender for a few days, surface electrodes are used→
That gives much less accurate results with a higher level of disturbance from the surrounding environment.

4. EMG Signal performing
To perform EMG, a needle electrode is inserted through the skin into the muscle tissue
Because of the needle electrodes, EMG may be somewhat painful or extremely painful to the patient, and the muscle may feel tender for a few days, surface electrodes are used
That gives much less accurate results with a higher level of disturbance from the surrounding environment.

5. Electromyogram (EMG) (cont.)

6. Blood Pressure

7. Blood Pressure Measurements
Pressure is force per unit area
Non-invasive measurement
Palpatory Method
Auscultatory Method
Oscillometric Method
Invasive measurement

8. Auscultatory Method systolic pressure diastolic pressure

9. Auscultatory Method
Pulse waves that propagate through the brachial artery, generate Korotkoff sounds.
There are 5 distinct phases in the Korotkoff sounds, which define SP and DP
The Korotkoff sounds are ausculted with a stethoscope or microphone (automatic measurement)
The frequency range is Hz and the accuracy is +/- 2mmHg (SP) and +/- 4mmHg (DP)
Also with this method, several measurements should be done.

10. Auscultatory Method (cont.)
ADVANTAGES
+) Auscultatory technique is simple and does not require much
equipment
DISADVANTAGES
-) Auscultatory tecnique cannot be used in noisy environment
-) The observations differ from observer to another
-) A mechanical error might be introduced into the system e.g. Mercury leakage, air leakage, obstruction in the cuff etc.
-) The observations do not always correspond with intra-arterial pressure
-) The technique does not give accurate results for infants and
hypotensive patients

11. Oscillometric Method
The intra-arterial pulsation is transmitted via cuff to transducer (e.g. piezo-electric)
The cuff pressure is deflated either linearly or stepwise
The arterial pressure oscillations (which can be detected throughout the measurement i.e. when Pcuff > SP and Pcuff< DP) are superimposed on the cuff pressure
SP and DP are estimated from the amplitudes of the oscillation by using a (proprietary) empirical algorithm.

12. Oscillometric Method (cont.)
ADVANTAGES
+) In the recent years, oscillometric methods have become popular for their simplicity of use and reliability.
+) MP can be measured reliably even in the case of hypotension
-) Many devices use fixed algorithms leading to large variance in blood pressures
DISADVANTAGE

13. Measurment disply

14. Electroencephalography (EEG)

15. EEG measurement
EEG is a representation (writing on paper or display on CRT, PC) of the electrical activity of brain
The electroencephalograph is an apparatus uses electrodes placed on a patient’s scalp to measure (detect), amplify, display in graphic form, and record the weak electrical signals generated by the brain
The technique involves the following:
Biopotential pickup: cranial or cerebral surface transducer electrode
EEG signal conditioning: transducer output amplification and filtering (0.1 to 100 Hz)
EEG signal recording: signal displayed on graphic recorder, CRT or PC
EEG signal analysis: visual or computer interpretation of resulting EEG

16. EEG measurement
Current due to voltage drops along the path of the axon  lead to scalp potentials (EEG).

17. EEG characteristic Alpha 8 - 13 Hz
Signal is generated in the brain
Voltage amplitude range is from 1 to 100 mV peak-to-peak at low frequencies (o.5 to 100 Hz)
EEG frequency bands:
Delta Hz
deep sleep, lucid dreaming, increased immune functions, hypnosis
Theta
4 - 8 Hz
deep relaxation, meditation, increased memory, focus, creativity, lucid dreaming, hyponagogic state
Alpha Hz
light relaxation, "super learning", positive thinking
Beta Hz
relaxed focus, improved attentive abilities
Gamma
22-30 Hz and higher
associated with information-rich task processing and high-level information processing

18. EEG electrode placement
Standard electrode placement known as system
10-20 system drives from the spacing of electrodes at intervals of 10% and 20% of the distance between particular points on the scalp
An asymmetry of 1 cm can alter an EEG reading
The EEG electrode placement system

19. EEG recording modes
Unipolar: Composed of a number of scalp leads connected to a common indifference point (one electrode is common to all channels such as an earlobe )
Unipolar

20. EEG recording modes (cont.)
Unipolar average: Composed of a number of scalp leads connected to a common indifference point (summation of scalp electrodes is common to all channels)
Unipolar average

21. EEG recording modes (cont.)
Bipolar: Achieved by the interconnection of scalp electrodes
Bipolar