1. Blood pressure measurement

2. Blood pressure measurement
Observation of blood pressure allows dynamic tracking of pathology and physiology affecting to the cardiovascular system, which has profound effects to all other organs of the body
High value increases the risk of heart attack and strokes
Low value increases the risk of lower oxygen perfusion e.g. in brains
However, the ’normal values’ differ from person to another
Values should be lower than 120 / 80 mmHg (systolic pressure (SP) / diastolic pressure (DP))
Mean pressure (MP)
average pressure during one cardiac cycle
driving force of the peripheral perfusion.
an estimate can be done by using an empirical formula:
SP and DP may vary significantly throughout the arterial system but MP is quite uniform (in normal situations)
Pulse pressure (PP) = SP-DP
MP = DP+PP/3

3. Blood Pressure Classification
BP classification
SBP (mmHg)
DBP (mmHg)
Normal
<= 120
And <= 80
Prehypertension
121 – 139 Or
Stage 1
Hypertension
140 – 159
Or 90 – 99
Stage 2
>= 160
Or >= 100

4. Blood Flow in our body
Devices: Aneroid. Mercury. Electronic.

6. Measurements in Blood 1 3 2 4 Blood Pressure Blood Flow
Ultrasound Doppler
Palpatory Method
(Riva-Rocci Method) 3
Laser Doppler Flowmetry
Auscultatory Method
Strain Gage Plethysmography
Non-Invasive
Ultrasonic Method
Electric-Impedance Plethysmogr.
Oscillometric Method
Photoelectric Plethysmography
Tonometry
Thermal Convection Probes 2 4
Extravascular Sensor
Dye Dilution Method
Invasive
Intravascular Sensor
Thermal Dilution Method
General on
System Parameters
Radioisotopes

7. Measurement of BP in the clinic
patient must be seated in a chair with arm support on both sides. The setting should be quiet and relaxed. It must be easy to adjust the height of the arm so that the middle of the cuff is at heart level (at the 4th intercostal space).

8. Indirect Methods in Blood Pressure Measurements
Indirect measurement = non-invasive measurement
Brachial artery is the most common measurement site
Close to heart
Convenient measurement
Other sites are e.g.:
forearm / radial artery
wrist (tends to give much higher SP)
The most common indirect methods are auscultation and oscillometry

9. Korotkoff’s method:
Putting a cuff around the upper part of the arm(veins are not occluded)
While air is leaked from the cuff, the korotkoff’s sounds are picked by a special piezoelectric sensor.
Amplified, bandpass filtered
More errors

10. Rheographic method: 3 electrodes
B electrode is common electrode – mid line
A and C placed at a distance from B
A high frequency current passes through A and C.
Impedance between these two elctrodes are measured.

11. Rheographic method:

12. Palpatory Method (Rheographic Method)
An occlusive cuff is placed on arm and inflated to Pcuff > SP. Then the cuff is deflated gradually and the measurement of blood flow is done
The occlusive cuff should be of a correct size in order to transmit the pressure to the artery evenly and thus to obtain accurate results
A short cuff requires special attention in placement. Longer cuff reduces this problem.
The cuff should be placed at the heart level in order to minimize the hydrostatic effects
When the cuff is deflated, there is a palpable pulse in the wrist. Pcuff = BP
Several measurements should be done as the respiration and vasomotor waves modulate the blood pressure levels
ADVANTAGES
The blood pressure can be measured in noisy environment too
Technique does not require much equipment
DISADVANTAGES
Only the systolic pressure can be measured (not DP)
The technique does not give accurate results for infants and hypotensive patients

13. Differential Asculatory method:
A pair of pressure sensitive element acts as an electrode.
Systolic: first opening of the artery occurs
Diastolic: relaxed state of blood flow.

14. Differential Asculatory method:

15. Differential Asculatory method:

16. Oscillometric measurement:
Advanced than ausculatory method.
No need of microphone
Oscillometric pulses are generated in the cuff during inflation or deflation

17. Oscillometric measurement:

18. Oscillometric measurement:

19. Ultrasonic Doppler shift method:
Arterial movement produces the Doppler frequency shift.
λc= Vc / fc
λc = wavelength (in m) of carrier frequency in the medium
Vc = velocity of the carrier frequency in the medium (1480 m/sec in water)
fc = carrier frequency in the medium

20. Ultrasonic Doppler shift method:

21. Ultrasonic Doppler shift method:

22. Direct method

23. Features: Highest degree of accuracy Dynamic response Invasive
Catheter tube.
A steady flow of sterile saline is passed through the catheter to prevent blood clotting.
Blood samples can be taken

24. Set up of direct method of BP measurement:

25. During measurement:

26. The actual pressure sensor can be e.g.
Extravascular Sensor
The ’normal’ measuring system
The sensor is located behind the catheter and the vascular pressure is transmitted via this liquid-filled catheter.
The actual pressure sensor can be e.g.
strain gage, variable inductance, variable capacitance, optoelectronic, piezoelectric, etc…
The hydraylic link is the major source of errors. The system’s natural frequency may be damped and degraded due (e.g.):

27. Blood Flow O 2 Blood Flow Blood Pressure ECG
O and other nutrition concentration in the cells are one of the primary measurements. 2 2
Blood flow helps to understand basic physiological processes and e.g. the dissolution of a medicine into the body.
Blood Flow
It also helps to understand many pathological conditions,
since many diseases alter the blood flow. Also the blood
clots in the arterial system can be detected.
Blood Pressure
Usually the blood flow measurements are more invasive than blood pressure measurements / ECG
ECG

28. Blood Flow (2)
Normal blood flow velocity 0,5 m/s – 1 m/s (Systolic, large vessel)

29. Heart Sounds LUB----------DUB
We have all heard the heart make the usual sounds.
LUB DUB
Lub is the first sound or S1
Dub is the second heart sound or S2

30. Systole The time between the S1 and S2 sounds is: Lub------------Dub
The ventricles contracting
Blood flowing from the heart to the lungs and body
Blood flowing across the Pulmonic and Aortic valves

31. Diastole Dub----------Lub
The time between S2 and S1 is :
The blood is flowing from the atria to the ventricles.
The blood flowing across the bicuspid and tricuspid valves.
The atrial contraction also occurs now.

32. S1 – First Heart Sound (LUB)
This sound is primarily because of the closing of the bicuspid and tricuspid valves.
Anatomically they are located between the atria and the ventricles
They close because the ventricles contract
The Pulmonic and Aortic valves are opening and blood is being forced into the arteries

33. S2 – Second Heart Sound (DUB)
The sounds are because of the closing of the Pulmonic and Aortic valves as the pressure from the arteries is greater then the pressure in the ventricles.
This is the end of systole

34. S3 – Third Heart Sound
also called a protodiastolic gallop, ventricular gallop
caused by Rapid ventricular filling.
It occurs at the beginning of diastole after S2.
The third heart sound is benign in youth, some trained athletes, and sometimes in pregnancy
The commonest causes are left ventricular failure and mitral regurgitation
It is best heard with the bell-side of the stethoscope at the apex of the heart .

35. S4 – Fourth Heart Sound called a presystolic gallop or atrial gallop.
This gallop is produced by the sound of blood being forced into a stiff/hypertrophic ventricle.
It is a sign of a pathologic state, (left ventriclular hypertrophy, hypertension, aortic stenosis)
It is best heard with the bell-side of the stethoscope at the apex of the heart .