Part b of the figure shows the streamlines of simple flow

Medical equipment and devices for 

monitoring of hemodynamic processes.

Viscometer

A viscometer (also called viscosimeter) is an instrument used to measure the viscosity of a fluid. For liquids with viscosities which vary with flow conditions, an instrument called a rheometer is used. Viscometers only measure under one flow condition.

In general, either the fluid remains stationary and an object moves through it, or the object is stationary and the fluid moves past it. The drag caused by relative motion of the fluid and a surface is a measure of the viscosity. The flow conditions must have a sufficiently small value of Reynolds number for there to be laminar flow.

At 20.00 degrees Celsius the viscosity of water is 1.002 mPas and its kinematic viscosity (ratio of viscosity to density) is 1.0038 mm2/s. These values are used for calibrating certain types of viscometer.

Standard laboratory viscometers for liquids

 

Ostwald viscometers measure the viscosity of a fluid with a known density.

U-tube viscometers

These devices also are known as glass capillary viscometers or Ostwald viscometers, named after Wilhelm Ostwald. Another version is the Ubbelohde viscometer, which consists of a U-shaped glass tube held vertically in a controlled temperature bath. In one arm of the U is a vertical section of precise narrow bore (the capillary). Above this is a bulb, with it is another bulb lower down on the other arm. In use, liquid is drawn into the upper bulb by suction, then allowed to flow down through the capillary into the lower bulb. Two marks (one above and one below the upper bulb) indicate a known volume. The time taken for the level of the liquid to pass between these marks is proportional to the kinematic viscosity. Most commercial units are provided with a conversion factor, or can be calibrated by a fluid of known properties. The time required for the test liquid to flow through a capillary of a known diameter of a certain factor between two marked points is measured. By multiplying the time taken by the factor of the viscometer, the kinematic viscosity is obtained.

Such viscometers are also classified as direct flow or reverse flow. Reverse flow viscometers have the reservoir above the markings and direct flow are those with the reservoir below the markings. Such classifications exists so that the level can be determined even when opaque or staining liquids are measured, otherwise the liquid will cover the markings and make it impossible to gauge the time the level passes the mark. This also allows the viscometer to have more than 1 set of marks to allow for an immediate timing of the time it takes to reach the 3rd mark, therefore yielding 2 timings and allowing for subsequent calculation of Determinability to ensure accurate results.

Falling sphere viscometers

Creeping flow past a sphere.

Stokes' law is the basis of the falling sphere viscometer, in which the fluid is stationary in a vertical glass tube. A sphere of known size and density is allowed to descend through the liquid. If correctly selected, it reaches terminal velocity, which can be measured by the time it takes to pass two marks on the tube. Electronic sensing can be used for opaque fluids. Knowing the terminal velocity, the size and density of the sphere, and the density of the liquid, Stokes' law can be used to calculate the viscosity of the fluid. A series of steel ball bearings of different diameter are normally used in the classic experiment to improve the accuracy of the calculation. The school experiment uses glycerine as the fluid, and the technique is used industrially to check the viscosity of fluids used in processes. It includes many different oils, and polymer liquids such as solutions.

In 1851, George Gabriel Stokes derived an expression for the frictional force (also called drag force) exerted on spherical objects with very small Reynolds numbers (e.g., very small particles) in a continuous viscous fluid by changing the small fluid-mass limit of the generally unsolvable Navier-Stokes equations:

F = 6 \pi r \eta v \,

where:

              Fis the frictional force,

              r is the radius of the spherical object,

              \etais the fluid viscosity, and

              vis the particle's velocity.

If the particles are falling in the viscous fluid by their own weight, then a terminal velocity, also known as the settling velocity, is reached when this frictional force combined with the buoyant force exactly balance the gravitational force. The resulting settling velocity (or terminal velocity) is given by:

V_s = \frac{2}{9}\frac{r^2 g (\rho_p - \rho_f)}{\mu}

where:

              Vs is the particles' settling velocity (m/s) (vertically downwards if \rho_p>\rho_f, upwards if \rho_p<\rho_f),

              ris the Stokes radius of the particle (m),

              g is the gravitational acceleration (m/s2),

              ρp is the density of the particles (kg/m3),

              ρf is the density of the fluid (kg/m3), and

              \muis the (dynamic) fluid viscosity (Pa s).

Note that Stokes flow is assumed, so the Reynolds number must be small.

A limiting factor on the validity of this result is the roughness of the sphere being used.

A modification of the straight falling sphere viscometer is a rolling ball viscometer which times a ball rolling down a slope whilst immersed in the test fluid. This can be further improved by using a patented V plate which increases the number of rotations to distance traveled, allowing smaller more portable devices. This type of device is also suitable for ship board use. Currently, new equipment is developed for viscosity measurements. This equipment is survismeter and not only measures viscosity only but along with viscosity, it also measures surface tension, interfacial tension, wetting coefficient with high accuracy and precision. The survismeter also measures a new parameter which is noted as friccohesity. The friccohesity establishes an interface between the cohesive forces and the frictional forces within the similar or dissimilar molecules, dispersed in desired medium.Friccohesity is intimately associated with distribution of the particles due to oscillations of the velocity components on gaining kinetic energy. Since friccohesity depicts demonstration of cohesive or potential forces and kinetic or frictional forces together and thus the particle distribution is automatically involved in the behavior of the mixtures. It is similar to melting of the ice or the solid state materials in parts because the particles which gain kinetic energy start moving in x,y,z directions with definite pressure and thus the less is the cohesive force more is the pressure exerted by the kinetically moving molecules which strike the walls. But when the molecules move on the fixed track that is noted under the capillary phenomenon within the rigid wall example is Schrodinger equation within the solid wall. Thus, the particles distribution occurs in 2 D Norcross In-Tank Viscometerand in such cases the friccohesity is called restricted friccohesity within boundaries.

Falling Piston Viscometer

 

Also known as the Norcross viscometer after its inventor, Austin Norcross. The principle of viscosity measurement in this rugged and sensitive industrial device is based on a piston and cylinder assembly. The piston is periodically raised by an air lifting mechanism, drawing the material being measured down through the clearance (gap) between the piston and the wall of the cylinder into the space which is formed below the piston as it is raised. The assembly is then typically held up for a few seconds, then allowed to fall by gravity, expelling the sample out through the same path that it entered, creating a shearing effect on the measured liquid, which makes this viscometer particularly sensitive and good for measuring certain thixotropic liquids. The time of fall is a measure of viscosity, with the clearance between the piston and inside of the cylinder forming the measuring orifice. The viscosity controller measures the time of fall (time-of-fall seconds being the measure of viscosity) and displays the resulting viscosity value. The controller can calibrate the time-of-fall value to cup seconds (known as efflux cup), Saybolt universal second (SUS) or centipoise.

Industrial use is popular due to simplicity, repeatability, low maintenance and longevity. This type of measurement is not affected by flow rate or external vibrations. The principle of operation can be adapted for many different conditions, making it ideal for process control environments.

Oscillating Piston Viscometer

Sometimes referred to as electromagnetic viscometer or EMV viscometer, was invented at Cambridge Viscosity (Formally Cambridge Applied Systems) in 1986. The sensor (see figure below) comprises a measurement chamber and magnetically influenced piston. Measurements are taken whereby a sample is first introduced into the thermally controlled measurement chamber where the piston resides. Electronics drive the piston into oscillatory motion within the measurement chamber with a controlled magnetic field. A shear stress is imposed on the liquid (or gas) due to the piston travel and the viscosity is determined by measuring the travel time of the piston. The construction parameters for the annular spacing between the piston and measurement chamber, the strength of the electromagnetic field, and the travel distance of the piston are used to calculate the viscosity according to Newtons Law of Viscosity.

Oscillating Piston Viscometer Schematic View

The oscillating piston viscometer technology has been adapted for small sample viscosity and micro-sample viscosity testing in laboratory applications. It has also been adapted to measure high pressure viscosity and high temperature viscosity measurements in both laboratory and process environments. The viscosity sensors have been scaled for a wide range of industrial applications such as small size viscometers for use in compressors and engines, flow-through viscometers for dip coating processes, in-line viscometers for use in refineries, and hundreds of other applications. Improvements in sensitivity from modern electronics, is stimulating a growth in oscillating piston viscometer popularity with academic laboratories exploring gas viscosity.

Vibrational viscometers

Vibrational viscometers date back to the 1950s Bendix instrument, which is of a class that operates by measuring the damping of an oscillating electromechanical resonator immersed in a fluid whose viscosity is to be determined. The resonator generally oscillates in torsion or transversely (as a cantilever beam or tuning fork). The higher the viscosity, the larger the damping imposed on the resonator. The resonator's damping may be measured by one of several methods:

1.           Measuring the power input necessary to keep the oscillator vibrating at a constant amplitude. The higher the viscosity, the more power is needed to maintain the amplitude of oscillation.

2.           Measuring the decay time of the oscillation once the excitation is switched off. The higher the viscosity, the faster the signal decays.

3.           Measuring the frequency of the resonator as a function of phase angle between excitation and response waveforms. The higher the viscosity, the larger the frequency change for a given phase change.

The vibrational instrument also suffers from a lack of a defined shear field, which makes it unsuited to measuring the viscosity of a fluid whose flow behaviour is not known before hand.

Vibrating viscometers are rugged industrial systems used to measure viscosity in the process condition. The active part of the sensor is a vibrating rod. The vibration amplitude varies according to the viscosity of the fluid in which the rod is immersed. These viscosity meters are suitable for measuring clogging fluid and high-viscosity fluids, including those with fibers (up to 1,000 Pas). Currently, many industries around the world consider these viscometers to be the most efficient system with which to measure the viscosities of a wide range of fluids; by contrast, rotational viscometers require more maintenance, are unable to measure clogging fluid, and require frequent calibration after intensive use. Vibrating viscometers have no moving parts, no weak parts and the sensitive part is very small. Even very basic or acidic fluids can be measured by adding a protective coating such as enamel, or by changing the material of the sensor to a material such as 316L stainless steel.

Rotational viscometers

Rotational viscometers use the idea that the torque required to turn an object in a fluid is a function of the viscosity of that fluid. They measure the torque required to rotate a disk or bob in a fluid at a known speed.

'Cup and bob' viscometers work by defining the exact volume of a sample which is to be sheared within a test cell; the torque required to achieve a certain rotational speed is measured and plotted. There are two classical geometries in "cup and bob" viscometers, known as either the "Couette" or "Searle" systems - distinguished by whether the cup or bob rotates. The rotating cup is preferred in some cases because it reduces the onset of Taylor vortices, but is more difficult to measure accurately.

'Cone and Plate' viscometers use a cone of very shallow angle in bare contact with a flat plate. With this system the shear rate beneath the plate is constant to a modest degree of precision and deconvolution of a flow curve; a graph of shear stress (torque) against shear rate (angular velocity) yields the viscosity in a straightforward manner.

Electromagnetically Spinning Sphere Viscometer (EMS Viscometer)

 

Measuring Principle of the Electromagnetically Spinning Sphere Viscometer

The EMS Viscometer measures the viscosity of liquids through observation of the rotation of a sphere which is driven by electromagnetic interaction: Two magnets attached to a rotor create a rotating magnetic field. The sample (3) to be measured is in a small test tube (2). Inside the tube is an aluminium sphere (4). The tube is located in a temperature controlled chamber (1) and set such that the sphere is situated in the centre of the two magnets. The rotating magnetic field induces eddy currents in the sphere. The resulting Lorentz interaction between the magnetic field and these eddy currents generate torque that rotates the sphere. The rotational speed of the sphere depends on the rotational velocity of the magnetic field, the magnitude of the magnetic field and the viscosity of the sample around the sphere. The motion of the sphere is monitored by a video camera (5) located below the cell. The torque applied to the sphere is proportional to the difference in the angular velocity of the magnetic field ΩB and the one of the sphere ΩS. There is thus a linear relationship between (ΩB−ΩS)/ΩS and the viscosity of the liquid.

This new measuring principle was developed by Sakai et al. at the University of Tokyo. The EMS viscometer distinguishes itself from other rotational viscometers by three main characteristics:

              All parts of the viscometer which come in direct contact with the sample are disposable and inexpensive.

              The measurements are performed in a sealed sample vessel.

              The EMS Viscometer requires only very small sample quantities (0.3 mL).

Stabinger viscometer

By modifying the classic Couette rotational viscometer, an accuracy comparable to that of kinematic viscosity determination is achieved. The internal cylinder in the Stabinger Viscometer is hollow and specifically lighter than the sample, thus floats freely in the sample, centered by centrifugal forces. The formerly inevitable bearing friction is thus fully avoided. The speed and torque measurement is implemented without direct contact by a rotating magnetic field and an eddy current brake. This allows for a previously unprecedented torque resolution of 50 pNm and an exceedingly large measuring range from 0.2 to 20,000 mPas with a single measuring system. A built-in density measurement based on the oscillating U-tube principle allows the determination of kinematic viscosity from the measured dynamic viscosity employing the relation

\nu = \frac {\eta} {\rho}

The Stabinger Viscometer was presented for the first time by Anton Paar GmbH at the ACHEMA in the year 2000. The measuring principle is named after its inventor Dr. Hans Stabinger.

Bubble viscometer

Bubble viscometers are used to quickly determine kinematic viscosity of known liquids such as resins and varnishes. The time required for an air bubble to rise is directly proportional to the viscosity of the liquid, so the faster the bubble rises, the lower the viscosity. The Alphabetical Comparison Method uses 4 sets of lettered reference tubes, A5 through Z10, of known viscosity to cover a viscosity range from 0.005 to 1,000 stokes. The Direct Time Method uses a single 3-line times tube for determining the "bubble seconds", which may then be converted to stokes.[1]

Micro-Slit Viscometers

Viscosity measurement using flow through a slit dates back to 1838 when Mr. Jean Louis Marie Poiseuille conducted experiments to characterize the liquid flow through a pipe. He found that a viscous flow through a circular pipe requires pressure to overcome the wall shear stress. That was the birth of Hagen-Poiseuille flow equation. The slit viscometer geometry has flows analogous to the cylindrical pipe but has the additional advantage that no entrance or exit pressure drop corrections are needed. Detailed information regarding the implementation of this principal with modern MEMS and microfluidic science is further explained in a paper by RheoSense, Inc.

Generally, the slit viscosity technology offers the following advantages:

              Measures true (absolute) viscosity for both Newtonian and non-Newtonian fluids[2]

              Enclosed system eliminates air interface and sample evaporation effects [3]

              Measurements can be made using very small sample volumes

              Laminar flow even at high shear rates due to low Reynolds number[4]

              Slit flow simulates real application flow conditions like drug injection or inkjetting.

Miscellaneous viscometer types

Other viscometer types use balls or other objects. Viscometers that can characterize non-Newtonian fluids are usually called rheometers or plastometers.

In the I.C.I "Oscar" viscometer, a sealed can of fluid was oscillated torsionally, and by clever measurement techniques it was possible to measure both viscosity and elasticity in the sample.

The Marsh funnel viscometer measures viscosity from the time (efflux time) it takes a known volume of liquid to flow from the base of a cone through a short tube. This is similar in principle to the flow cups (efflux cups) like the Ford, Zahn and Shell cups which use different shapes to the cone and various nozzle sizes. The measurements can be done according to ISO 2431, ASTM D1200 - 10 or DIN 53411.

 

Invasive measurement

Arterial blood pressure is most accurately measured invasively through an arterial line (catheter). Invasive arterial pressure measurement with intravascular cannulae involves direct measurement of arterial pressure by placing a cannula needle in an artery (usually radial, femoral, dorsalis pedis or brachial). This is usually done by an anesthesiologist or surgeon in a hospital.

The cannula must be connected to a sterile, fluid-filled system, which is connected to an electronic pressure transducer. The advantage of this system is that pressure is constantly monitored beat-by-beat, and a waveform (a graph of pressure against time) can be displayed. This invasive technique is regularly employed in human and veterinary intensive care medicine, anesthesiology, and for research purposes.

 

Cannulation for invasive vascular pressure monitoring is infrequently associated with complications such as thrombosis, infection, and bleeding. Patients with invasive arterial monitoring require very close supervision, as there is a danger of severe bleeding if the line becomes disconnected.

It is generally reserved for patients where rapid variations in arterial pressure are anticipated

Invasive vascular pressure monitors are pressure monitoring systems designed to acquire pressure information for display and processing. There are a variety of invasive vascular pressure monitors for trauma, critical care, and operating room applications. These include single pressure, dual pressure, and multi-parameter (i.e. pressure / temperature).

The monitors can be used for measurement and follow-up of arterial, central venous, pulmonary arterial, left atrial, right atrial, femoral arterial, umbilical venous, umbilical arterial, and intracranial pressures.

Vascular pressure parameters are derived in the monitor's microcomputer system. Usually, systolic, diastolic, and mean pressures are displayed simultaneously for pulsatile waveforms (i.e. arterial and pulmonary arterial). Some monitors also calculate and display CPP (cerebral perfusion pressure). Normally, a zero key on the front of the monitor makes pressure zeroing extremely fast and easy. Alarm limits may be set to assist the medical professional responsible for observing the patient. High and low alarms may be set on displayed temperature parameters.

 

Non-invasive measurement

Arterial pressure is most commonly measured via a sphygmomanometer, which uses the height of a column of mercury to reflect the circulating pressure (Non-invasive measurement).

Arterial blood pressure values are reported in either kilopascals (kPa) or in millimetres of mercury (mmHg), despite the fact that many modern vascular pressure devices no longer use mercury.

The systolic arterial pressure is defined as the peak pressure in the arteries, which occurs near the beginning of the cardiac cycle; the diastolic arterial pressure is the lowest pressure (at the resting phase of the cardiac cycle). The average pressure throughout the cardiac cycle is reported as mean arterial pressure; the pulse pressure reflects the difference between the maximum and minimum pressures measured.

The non-invasive auscultatory and oscillometric measurements are simpler and quicker than invasive measurements, require less expertise in fitting, have virtually no complications, and are less unpleasant and painful for the patient.

However, non-invasive measures may yield somewhat lower accuracy and small systematic differences in numerical results. Non-invasive measurement methods are more commonly used for routine examinations and monitoring.

 

PALPATION METHODS

A minimum systolic value can be roughly estimated without any equipment by palpation, most often used in emergency situations.

It has been estimated that, using 50% percentiles:

            carotid, femoral and radial pulses are present in patients with a systolic blood pressure > 70 mmHg;

            carotid and femoral pulses are present alone in patients with systolic blood pressure of > 50 mmHg;

            only a carotid pulse is present in patients with a systolic blood pressure of > 40 mmHg.

However, one study indicated that this method was not accurate enough and often overestimated patient's systolic blood pressure.

A more accurate value of systolic blood pressure can be obtained by with a sphygmomanometer and palpating for when a radial pulse returns. Because a diastolic pressure cannot be obtained by this method, blood pressures obtained by palpation are noted as "<systolic>/P".

A more accurate value of systolic blood pressure can be obtained with a sphygmomanometer and palpating the radial pulse. The diastolic blood pressure cannot be estimated by this method. The American Heart Association recommends that palpation be used to get an estimate before using the auscultatory method.

 

AUSCULTATORY METHODS

The auscultatory method (from the Latin for listening) uses a stethoscope and a sphygmomanometer. This comprises an inflatable (Riva-Rocci) cuff placed around the upper arm at roughly the same vertical height as the heart, attached to a mercury or aneroid manometer.

The mercury manometer, considered to be the gold standard for arterial pressure measurement, measures the height of a column of mercury, giving an absolute result without need for calibration, and consequently not subject to the errors and drift of calibration which affect other methods. The use of mercury manometers is often required in clinical trials and for the clinical measurement of hypertension in high risk patients, such as pregnant women.

The cuff pressure is further released until no sound can be heard (fifth Korotkoff sound), at the diastolic arterial pressure. Sometimes, the pressure is palpated (felt by hand) to get an estimate before auscultation.

: http://zdorove-sertse.com.ua/wp-content/uploads/2011/07/rtutnyi-tonometr1-150x150.jpgThe procedure for measuring blood pressure with a manometer:

- a cuff of appropriate size is fitted;

- then it is inflated manually by repeatedly squeezing a rubber bulb until the artery is completely occluded;

- listening with the stethoscope to the brachial artery at the elbow, the examiner slowly releases the pressure in the cuff;

- when blood just starts to flow in the artery, the turbulent flow creates a "whooshing" or pounding (first Korotkoff sound). The pressure at which this sound is first heard is the systolic blood pressure.

- the cuff pressure is further released until no sound can be heard (fifth Korotkoff sound), at the diastolic arterial pressure.

 

OSCILLOMETRIC METHODS

: http://zdorove-sertse.com.ua/wp-content/uploads/2011/07/oscylometricheskii-metod.jpgThe oscillometric method was first demonstrated in 1876 and involves the observation of oscillations in the sphygmomanometer cuff pressure which are caused by the oscillations of blood flow, i.e., the pulse.

The electronic version of this method is sometimes used in long-term measurements and general practice.

It uses a sphygmomanometer cuff (like the auscultatory method), but with an electronic pressure sensor (transducer) to observe cuff pressure oscillations, electronics to automatically interpret them, and automatic inflation and deflation of the cuff.

To maintain accuracy, calibration must be checked periodically, unlike the inherently accurate mercury manometer. In most cases the cuff is inflated and released by an electrically operated pump and valve, which may be fitted on the wrist (elevated to heart height), although the upper arm is preferred. They vary widely in accuracy, and should be checked at specified intervals and if necessary recalibrated.

Oscillometric measurement requires less skill than the auscultatory technique and may be suitable for use by untrained staff and for automated patient home monitoring.

The procedure for the oscillometric measurement of the blood pressure:

              the cuff is inflated to a pressure initially in excess of the systolic arterial pressure;

              and then reduces to below diastolic pressure over a period of about 30 seconds.

: http://zdorove-sertse.com.ua/wp-content/uploads/2011/07/elektronnyi-tonometr.jpgWhen blood flow is nil (cuff pressure exceeding systolic pressure) or unimpeded (cuff pressure below diastolic pressure), the cuff pressure will be essentially constant.  It is essential that the cuff size is correct: undersized cuffs may yield too high a pressure, whereas oversized cuffs yields too low a pressure.

When blood flow is present, but restricted, the cuff pressure, which is monitored by the pressure sensor, will vary periodically in synchrony with the cyclic expansion and contraction of the brachial artery, i.e., it will oscillate.

The values of systolic and diastolic pressure are computed, not actually measured from the raw data, using an algorithm; the computed results are displayed.

Oscillometric monitors may produce inaccurate readings in patients with heart and circulation problems that include arterial sclerosis, arrhythmia, preeclampsia, pulsus alternans (physical finding with arterial pulse waveform showing alternating strong and weak beats), and pulsus paradoxus (an abnormally large decrease in systolic blood pressure and pulse wave amplitude during inspiration).

In practice the different methods do not give identical results; an algorithm and experimentally obtained coefficients are used to adjust the oscillometric results to give readings which match the auscultatory as well as possible.

Some equipment uses computer-aided analysis of the instantaneous arterial pressure waveform to determine the systolic, mean, and diastolic points. Since many oscillometric devices have not been validated, caution must be given as most are not suitable in clinical and acute care settings.

 

Conditions necessary for the accurate measurement of the blood pressure indices

- half an hour before taking the blood pressure measurement, refrain from smoking and even drinking coffee or alcohol;

- you must also urinate and relieve yourself, as the full bladder can affect the results of the measurements;

- for the accurate blood pressure measurement, rest for at least 5 minutes before taking BP readings;

- you can say that you have ideal blood pressure when you take the measurement in the appropriate manner.

 

1.1 The study of the influence of the media factors on the functioning of the cardiovascular system.

The objective of the study was to examine the speed of adaptation of the cardiovascular system after loading and the influence of the multimedia factors on both loading and adaptation.

30 squats in 45 seconds and the recognized method for assessing cardiac activity during physical exercise the Ruffier-Dickson test were selected as the physical load. This test is described in the following:

After 5-minute rest in a sitting position the pulse is measured for 15 s (P1), then the pulse is measured after 30 squats in 45 s. Immediately after squatting the pulse is measured for the first 15 s (P2) and last 15 s (P3) of the first minute of the recovery period. The results are measured by the index that is defined by the formula:
The Ruffier index = (4 (1 + 2 + 3) - 200) / 10

For the more profound study we measured the value of the pulse and pressure and not only before the test (P1), after the test for the first 15 s (P2), the last 15 s (P3) of the first minute of the recovery period and at the end of the second and third minute, but after 20-30 minutes we repeated the test, during which the students were offered to listen to music, statements focused on health issues and to watch videos with beautiful sceneries.

All these compositions were chosen taking into account the developments in the fields of rehabilitation, psychology, reflexology and etc.

The study of the physical condition of students (Ruffiers method)

The 1st-stage of the experiment

1.   To sit at the table and to fit the cuff on the right shoulder.

2.   To measure the value of the pulse and pressure 15 seconds before the physical load (P1).

3.   To squat 30 times in 45 seconds.

4.   To measure the value of the pulse and pressure after the physical load (P2).

5.   To perform the next measurement of the pulse and pressure (P3) after 30 seconds.

6.   To measure the pulse and pressure at the end of 2nd and 3 minutes after squatting and to record their values (P4 and P5).

7.   To fill in the 1st line of the Table with the measured values.

 

 

1

2

3

4

5

 

Pulse

Pressure

Pulse

Pressure

Pulse

Pressure

Pulse

Pressure

Pulse

Pressure

1

 

 

 

 

 

 

 

 

 

 

Mean arterial pressure

 

 

 

 

 

 

 

 

 

 

Ruffier index

 

 

 

 

 

 

 

 

 

 

2

 

 

 

 

 

 

 

 

 

 

Mean arterial pressure

 

 

 

 

 

 

 

 

 

 

Ruffier index

 

 

 

 

 

 

 

 

 

 

 

The 2nd stage of the experiment

To analyze the influence of video images and music on the organism after the physical load (Ruffiers method):

1.   To sit at the table and to fit the cuff on the right shoulder.

2.   To measure the value of the pulse and pressure 15 seconds before the physical load (P1).

3.   To squat 30 times in 45 seconds.

4.   To measure the value of the pulse and pressure after the physical load (P2).

5.   To perform the next measurement of the pulse and pressure (P3) after 30 seconds.

6.   To watch a video watch.

7.   To measure the pulse and pressure at the end of 2nd and 3 minutes after squatting and to record their values (P4 and P5).

8.   To fill in the 2nd line of the Table with the measured values.

9.   To calculate the Ruffier index for the values of the first line and for the values of the second line of the table:

 

;

 

The values correspond to a very good physical condition.

The values from 5 to 10 correspond to a good physical condition.

The values from 10 to 15 correspond to the heart failure.

 

The 3d stage of the experiment

1.          To construct the graph for the heart rate of 5 measurements in the 1st and 2nd experiment.

2.          To construct the graph for the systolic and diastolic values of the blood pressure of 5 measurements in the 1st and 2nd experiment.

3.          To calculate the systolic and diastolic values with the oscillometric method using the measurements of Halter monitor VAT-41.

4.          To find the maximum amplitude in the measurement of the blood pressure. The formula for calculating the amplitudes of systolic and diastolic blood pressure is defined as:

5.          To calculate the value of the pressure according to the image and the value according to your version.

Make a conclusion:

1. How would you describe your physical condition?

2. How did the value of the pulse and the value of the mean pressure change at the end of 2nd and 3 minutes between the first and second experiment

 

Fig. 1. The curve of the change of the maximum amplitude to the pressure.

 

Fig. 2. The graph of the amplitude versus the pressure.

 

 

 

32.281250 0.359375

35.843750 0.500000

39.187500 0.421875

42.234375 0.421875

46.031250 0.781250

49.531250 0.890625

52.109375 0.921875

55.828125 1.031250

59.375000 1.078125

62.968750 1.062500

65.531250 1.406250

68.437500 1.734375

 

71.187500 1.843750

74.562500 2.171875

76.968750 3.062500

80.031250 3.500000

82.593750 3.625000

85.375000 3.546875

89.312500 3.796875

93.468750 3.671875

97.453125 3.406250

100.421875 2.703125

104.125000 2.984375

107.640625 2.890625

 

110.859375 2.562500

114.375000 2.203125

117.703125 2.406250

121.437500 2.140625

125.328125 1.843750

128.187500 1.734375

131.234375 1.484375

135.765625 1.078125

 

 

=35/64=0,546875

=39/64=0,609375

 

 

Fig. 3. The graph of the changes in the pressure versus time.

The calculation of the value of the systolic and diastolic pressure with the 40 device:

1.          To measure the blood pressure with the device.

2.          After the measurement the results are imported to a PC. A text file with information about the amplitude of blood waves during the corresponding pressure in the cuff. Table 1 presents the data of a measurement.

3.          Among the data of the amplitudes recorded in a text file, the maximum amplitude has to be found . In our Table 1

4.          To calculate the value with the following formula:

 

5. To find the value on the axis in Fig. 3.

 

 

Measuring blood preasure Korotkovs metod.

1. Put the patient and impose a cuff on the brachial artery.

2. Identify the location artery pulsation in ulnar fossa with its inside and attach to this place+9 Phonendoscopes.

3. Frequent but not severe compression of the rubber balloon pump air into the tonometer and the United cuff with him, until until through phonendoscope not stop wiretapped sound effects.

4. With the tap slowly let air out of cuff and tonometer. Identify the divisions on which the arrow is set tonometer, when the first tone, which corresponds to the maximum pressure and when a substantial reduction of sound effects, relaxation tones corresponding to minimum pressure.

5. Measurement of blood pressure to perform three times with an interval of 4-5 min.

6. Compute the average of three measurements.

7. Find the absolute and relative error for maximum and minimum pressures.

8. Determine the value of pulse pressure.

 

Here we survey modern methods for measuring the hydrodynamic properties of biological macromolecules and for calculating the hydrodynamic properties of useful models for biomolecules.

Hydrodynamic properties are quantities like sedimentation and diffusion coefficient, rotational relaxation time, intrinsic viscosity, and viscoelastic relaxation time. They enable one to determine how rapidly molecules translate and rotate in solution, and how they influence the steady state and time-dependent viscosity of solutions. These measured properties, in turn, when interpreted in terms of suitable models, give us information about the molecular weight, size, hydration, shape, exibility, conformation, and degree of association of biological macromolecules.

Like so much of science, hydrodynamics has a long history, but has been dramatically hanged by recent advances in experiment, theory, and computation. Classic textbooks tell of the experimental work of Fick in 1855 on diffusion, Svedberg in the 1920s on sedimentation, and Poiseuille in 1846 on viscosity. Theories for simple shapes such as spheres and ellipsoids were worked out by Stokes (1847), Einstein (1906), and Perrin (1936). However, recent experimental developments such as dynamic laser light scattering, nanosecond fluorescence depolarization measurements, fluorescence recovery after photoblea hing,.uorescence correlation spectroscopy, pulsed field gradient NMR, and improved analytical ultracentrifuge design have made measurements of hydrodynamic properties more convenient, precise, and refined. At the same time, development of new theoretical and computational tools have enabled calculation of the properties of complex, realistic molecular models.

 

Fluids In motion

Part b of the figure shows the streamlines of simple flow. These lines show the path a tiny particle in the fluid follows as it moves along the pipe. Flow such as this is termed laminar flow.

The fluid velocity is lower in the large cross-sectional region. Part c of the figure shows what happens if the flow becomes too swift past an obstruction. The smooth flow lines no longer exist. As the fluid rushes past the obstacle, it starts to swirl in erratic motion. No longer can one predict the exact path a particle will follow. This region of constantly changing flow lines is said to consist of turbulent flow.

We saw in the last section that friction effects occur in a flowing fluid. This effect is described in terms of the viscosity of the fluid Viscosity measures how much force is required to slide one layer of the fluid over another layer. Substances which do not flow easily, such as thick tar or syrup, have large viscosity. Substances (like water) which flow easily have small viscosity

 

The Equation of Continuity

Up to now, we have studied only fluids at rest. Let us now study fluids in motion, the subject matter of hydrodynamics. The study of fluids in motion is relatively complicated, but the analysis can be simplified by making a few assumptions. Let us assume that the fluid is incompressible and flows freely without any turbulence or friction between the various parts of the fluid itself and any boundary containing the fluid, such as the walls of a pipe. A fluid in which friction can be neglected is called a nonviscous fluid. A fluid, flowing steadily without turbulence, is usually referred to as being in streamline flow. The rather complicated analysis is further simplified by the use of two great conservation principles: the conservation of mass, and the conservation of energy. The law of conservation of mass results in a mathematical equation, usually called the equation of continuity. The law of conservation of energy is the basis of Bernoulli's theorem.

Let us consider an incompressible fluid flowing in the pipe of figure 1. At a particular instant of time the small mass of fluid , shown in the left-hand portion of the pipe will be considered.

(1)

Because the pipe is cylindrical, the small portion of volume of fluid is given by the product of the cross-sectional area A1 times the length of the pipe containing the mass, that is,

(2)

The length of the fluid in the pipe is related to the velocity of the fluid in the left-hand pipe. Because the fluid in moves a distance in time, . Thus,

(3)

Substituting equation 3 into equation 2, we get for the volume of fluid,

(4)

Figure 1. The law of conservation of mass and the equation of continuity.

 

Substituting equation 4 into equation 1 yields the mass of the fluid as

(5)

We can also express this as the rate at which the mass is flowing in the left-hand portion of the pipe by dividing both sides of equation 5 by . Thus

(6)

(7)

Equation 7 is called the equation of continuity and is an indirect statement of the law of conservation of mass. Since we have assumed an incompressible fluid, the densities on both sides of equation 7 are equal and can be canceled out leaving. When the cross-sectional area of a pipe gets smaller, the velocity of the fluid must become greater in order that the same amount of mass passes a given point in a given time. Conversely, when the cross-sectional area increases, the velocity of the fluid must decrease.

 

Bernoullis equation

Bernoulli's theorem is a fundamental theory of hydrodynamics that describes a fluid in motion. It is really the application of the law of conservation of energy to fluid flow. Let us consider the fluid flowing in the pipe of figure 1. The left-hand side of the pipe has a uniform cross-sectional area ,which eventually tapers to the uniform cross-sectional area A2 of the right-hand side of the pipe. The pipe is filled with a nonviscous, incompressible fluid. A uniform pressure p\ is applied, such as from a piston, to a small element of mass of the fluid Am and causes this mass to move through a distance Ax\ of the pipe. Because the fluid is incompressible, the fluid moves throughout the rest of the pipe. The same small mass Am, at the right- hand side of the pipe, moves through a distance

Figure 2. Bernoulli's theorem.

Bernoulli's theorem. It says that the sum of the pressure, the potential energy per unit volume, and the kinetic energy per unit volume at any one location of the fluid is equal to the sum of the pressure, the potential energy per unit volume, and the kinetic energy per unit volume at any other location in the fluid, for a nonviscous, incompressible fluid in streamlined flow.

Since this sum is the same at any arbitrary point in the fluid, the sum itself must therefore be a constant. Thus, we sometimes write Bernoulli's equation in the equivalent form

The Flow of a Liquid Through an Orifice

Let us consider the large tank of water shown in figure 2. Let the top of the fluid be location 1 and the orifice be location 2. Bernoulli's theorem is

But the pressure at the top of the tank and the outside pressure at the orifice are both p0, the normal atmospheric pressure. Also, because of the very large volume of fluid, the small loss through the orifice causes an insignificant vertical motion of the top of the fluid Bernoulli's equation becomes

The pressure term p0 on both sides of the equation cancels out. Also h2 is very small compared to h1 and it can be neglected, leaving

Solving for the velocity of efflux, we get

Figure 3.

Viscosity is a measure of a fluid's resistance to flow. It describes the internal friction of a moving fluid. A fluidwith large viscosity resists motion because its molecular makeup gives it a lot of internal friction. A fluid with low viscosity flows easily because its molecular makeup results in very little friction when it is in motion.

In everyday terms (and for fluids only), viscosity is "thickness" or "internal friction". Thus, water is "thin", having a lower viscosity, while honey is "thick", having a higher viscosity. Put simply, the less viscous the fluid is, the greater its ease of movement (fluidity).

Viscosity describes a fluid's internal resistance to flow and may be thought of as a measure of fluid friction. For example, high-viscosity felsic magma will create a tall, steep stratovolcano, because it cannot flow far before it cools, while low-viscosity mafic lava will create a wide, shallow-sloped shield volcano.

With the exception of superfluids, all real fluids have some resistance to stress and therefore are viscous. A fluid which has no resistance to shear stress is known as an ideal fluid or inviscid fluid. In common usage, a liquid with the viscosity less than water is known as a mobile liquid, while a substance with a viscosity substantially greater than water is simply called a viscous liquid.

The study of flowing matter is known as rheology, which includes viscosity and related concepts.

Laminar shear of fluid between two plates. Friction between the fluid and the moving boundaries causes the fluid to shear. The force required for this action is a measure of the fluid's viscosity. This type of flow is known as a Couette flow.

Laminar shear, the non-constant gradient, is a result of the geometry the fluid is flowing through (e.g. a pipe).

 

In general, in any flow, layers move at different velocities and the fluid's viscosity arises from the shear stress between the layers that ultimately opposes any applied force. The relationship between the shear stress and the velocity gradient can be obtained by considering two plates closely spaced at a distance y, and separated by a homogeneous substance. Assuming that the plates are very large, with a large area A, such that edge effects may be ignored, and that the lower plate is fixed, let a force F be applied to the upper plate. If this force causes the substance between the plates to undergo shear flow with a velocity gradient u/y (as opposed to just shearing elastically until the shear stress in the substance balances the applied force), the substance is called a fluid.

Newtons equation for fluids

The applied force is proportional to the area and velocity gradient in the fluid:

where - is the proportionality factor called dynamic viscosity.

Poiseuille formula

Hydraulic resistence

 

Reynolds number

In 1851, George Gabriel Stokes derived an expression, now known as Stokes' law, for the frictional force also called drag force exerted on spherical objects with very small Reynolds numbers (e.g., very small particles) in a continuous viscous fluid. Stokes' law is derived by solving the Stokes flow limit for small Reynolds numbers of the generally unsolvable NavierStokes equations:[1]

F_d = 6 \pi\,\mu\,R\,v_s\,

where:

     Fd is the frictional force known as Stokes' drag acting on the interface between the fluid and the particle (in N),

     μ is the dynamic viscosity (N s/m2),

     R is the radius of the spherical object (in m), and

     vs is the particle's settling velocity (in m/s).

If the particles are falling in the viscous fluid by their own weight due to gravity, then a terminal velocity, also known as the settling velocity, is reached when this frictional force combined with the buoyant force exactly balance the gravitational force. The resulting settling velocity (or terminal velocity) is given by:[2]

v_s = \frac{2}{9}\frac{\left(\rho_p - \rho_f\right)}{\mu} g\, R^2

where:

     vs is the particles' settling velocity (m/s) (vertically downwards if ρp > ρf, upwards if ρp < ρf ),

     g is the gravitational acceleration (m/s2),

     ρp is the mass density of the particles (kg/m3), and

     ρf is the mass density of the fluid (kg/m3).

24-hour blood pressure monitoring: what are the benefits

 

Ambulatory 24-hour blood pressure monitoring may become an indispensable tool in the diagnosis and treatment of hypertension if its precise role is determined. The major advantage of monitoring over single clinic pressures is its ability to detect 'white coat' and labile hypertension. Currently, its general use is limited by a lack of cost-effectiveness data.

However, its ability to detect subjects with 'white coat' hypertension, who probably do not need treatment, should lead to a significant reduction in drug costs. Non-invasive ambulatory blood pressure monitoring (ABPM) is being increasingly used to assess patients with hypertension. This trend is supported by evidence that 24-hour blood pressure profiles may be superior to isolated clinic pressures and the new monitors are acceptable to patients.1 The development of such a blood pressure profile means that established correlations of clinic pressures with cardiovascular morbidity and mortality in treated and untreated patients must be reviewed and repeated with ABPM. Normal ABPM reference values have been devised and the association of ABPM profiles with surrogate cardiovascular end-points such as left ventricular hypertrophy is being established. ABPM has several indications (Table

1) but appears to be of particular value in detecting patients with 'white coat' hypertension who may not need treatment. It is also used to assess antihypertensive treatment in clinical trials.

However, its cost-effectiveness in routine clinical practice has not been established.

 

Caution

While the use of ABPM is increasing and the benefits of such devices are becoming more apparent, it must not be forgotten that these new methods have not been evaluated as

comprehensively as clinic pressures. The benefits of drug treatment in significantly lowering morbidity and mortality have only been proven using clinic blood pressures.

 

How they work

Most devices use either brachial artery microphones to detect Korotkoff sounds or cuff oscillometry where cuff pressure oscillations are detected. The measurement

frequency can be varied, but it is usually between 20-30 minutes while awake and 30-60 minutes while sleeping. Patients can start or stop recordings and they can read the displayed results if they wish. Patient diaries are encouraged so that the cause of sudden changes in blood pressure can be evaluated. The units function poorly during strenuous activity and work best if the patient slows or stops moving.

Patient acceptance

New generation devices are small (the size of a personal cassette player), light, and quiet, so patient acceptance is good. When recently evaluated in general practice, 49% of patients reported some interference with normal activity and 76% reported some disruption of sleep. Bed partners may also complain of interrupted sleep. The main adverse effect is bruising from the cuff and occasionally a petechial rash, particularly if the patient has fat arms or if the cuff inflation pressure is high. Ulnar nerve palsy is rare.

 

In patients with newly discovered 'hypertension' whose casual office or clinic blood pressure levels are in the mild category (diastolic blood pressure under 105 mmHg) with no evidence of target organ damage.

In patients with borderline or labile hypertension.

For blood pressure management in the compliant patient whose blood pressure is apparently poorly controlled, despite the use of appropriate antihypertensive drug therapy.

In patients who exhibit worsening of end organ damage, despite adequate blood pressure control on office or clinic readings.

In patients with a history suggestive of syncope or orthostatic hypotension. In such patients, ambulatory blood pressure monitoring may be best used in conjunction with Holter monitoring. Where there are symptoms or signs suggestive of episodic hypertension, as in phaeochromocytoma. In clinical research. Significant treatment effects can be seen with smaller numbers of patients. Duration of effects of antihypertensive therapy can be carefully assessed. Evaluation of ABP profiles in disease states, effects of therapies on ABP components and their significance are fertile areas for research.

 

Device validation

Approximately 30 manufacturers market more than 40 devices and less than 50% have been validated for accuracy according to two current protocols (Association for the Advancement of Medical Instrumentation and the British Hypertension Society). Of these, only 9 fulfilled their criteria and achieved at least a B/B grading for systolic and diastolic blood pressure where the mean difference between the ABPM and a mercury standard was less than 5 mmHg with a standard deviation of <8 mmHg.2 Apart from device validation, each recorder should be calibrated against a mercury column before each use and blood pressure cuffs should be the appropriate size for the arm circumference. How many doctors periodically check their mercury or aneroid sphygmomanometer and ensure that the correct cuff is used? Results from oscillometric and auscultatory devices appear to be comparable; however, most monitors are unreliable when used in patients with atrial fibrillation or frequent ectopics where the error rate can be from 5-20%. A loss of accuracy may occur in the elderly as well as in patients with very high blood pressure. In addition, problems can occur when evaluating results from devices that use ECG gating if fitted to patients with pacemakers. These devices relate Korotkoff sounds to the QRS complex to improve the accuracy of blood pressure monitoring.

Normal range

A number of studies, both large and small, have attempted to develop population reference values including a normal range for ABPM.3,4 More data are required to develop more accurate population reference ranges. Clinic and 24-hour ambulatory daytime blood pressures are remarkably similar in normotensive patients,

yet in hypertensives (borderline or definite), ABPM results are much lower. Also, work-day pressures are usually higher than non-work-day pressures in both hypertensives and normotensives.

'White coat' hypertension

The definition of 'white coat' hypertension is arbitrary.1 A general definition is 'a persistently raised clinic blood pressure

together with a normal ambulatory pressure'. This implies that several clinic visits have occurred to exclude the tendency of most clinic pressures to fall with repeated measures. All health professionals are aware of the marked variability of any individual's blood pressure including the effects of physical and mental stress. A clinic visit can probably provoke a press or response in some people that persists with time and subsequent readings. Unfortunately, this 'white coat' effect is not confined to subjects with 'white coat' hypertension and can occur in patients with severe hypertension.

'White coat' hypertension cannot be easily predicted by either the patient's personality (most patients deny anxiety and their pulse rate is not usually increased) or cardiovascular profile. It can occur in both young and old, and can alter both systolic and diastolic pressures; particularly the systolic. Demographic factors including gender and obesity can influence the prevalence of 'white coat' hypertension and it is even common in patients over the age of 65 with isolated systolic hypertension. The scale of this condition was revealed by a study where 4577 ABPM profiles from

24 centres world-wide were evaluated and compared with their clinic pressures.3 Between 24% and 30% of the patients who were considered to have mild hypertension (diastolic blood pressure 90-105 mmHg) on traditional clinic pressures had ABPM profiles within the 'normal' range. While this study may overestimate the 'white coat' effect since many patients with labile blood pressure may have been referred to these clinics, other hospital and private practice based studies have found a prevalence of 'white coat' hypertension in patients with mild to moderate hypertension of 20-40%.

While it is not yet clear how many of these patients with a 'white coat' syndrome will develop sustained hypertension, their prognosis appears favourable with a recent study of 1187 adults with

essential hypertension, some followed for over 7 years. In the 20% who were considered to have 'white coat' hypertension, the numbers of fatal and non-fatal cardiovascular events were similar to a normotensive control group.5 Therefore, on current evidence, such patients are unlikely to benefit from immediate drug treatment. However, periodic review of such patients is prudent.

Dippers and non-dippers

Most people, including the majority of patients with hypertension, have a lower blood pressure while asleep (dippers). The systolic and diastolic falls in

hypertensive patients are usually 10-15%, but do not fall to normal levels. However, in 30% of hypertensive patients, the nocturnal fall is smaller than usual, may not occur, or the pressure may even rise. It may be important to identify this group of 'non-dippers' because, from preliminary data, they appear to have a worse prognosis. This can be measured as cardiovascular morbidity and mortality as well as increased end organ damage including left ventricular hypertrophy. ABPM is the simplest way to detect 'non-dippers'. As a group, they appear to have more severe or complicated forms of hypertension and are often older. One study found that 5 fatal and non-fatal cardiovascular events per 100 patient years occurred in 'non-dippers' compared with two such events in 'dippers'.5 Other illnesses such as pre-eclampsia, heart failure and sleep apnoea can reverse the normal diurnal variation in blood pressure.

Left ventricular hypertrophy - a surrogate end-point

Left ventricular hypertrophy (LVH) is not only a consequence of hypertension, but also an independent risk factor for coronary

artery disease and cardiac death. A number of studies have investigated if ABPM is a better predictor of LVH than clinic pressures. To date, most studies show a much greater predictive value of ABPM.

In a recent meta-analysis of 19 studies, night-time blood pressures were no better than daytime pressures in predicting LVH.6 While this might suggest that daytime

monitoring is probably all that is necessary in most patients, and this is clearly more convenient, only night-time monitoring will indicate 'non-dippers'.

As many pressures are recorded during a 24-hour period, attempts have been made to convert these data into more meaningful information. Consequently, most devices will calculate the blood pressure

load from the proportion of systolic pressures >140 mmHg and diastolic pressures >90 mmHg while awake and 120 and 80 mmHg respectively while asleep.7 This approach recognises that fluctuations in blood pressure throughout the day and night are at least as important as the average pressures and appear to be an even better predictor of LVH.

Evaluation of antihypertensive drugs ABPM has been particularly valuable in the testing of new (and also older) drugs. While trough-peak ratios calculated from ABPM have become a new surrogate treatment end-point and are now being used in marketing strategies, such an assessment of the ability of medications to lower blood pressure persistently over 24 hours when compared to placebo has been valuable. Unfortunately, many recent trough-peak ratio studies that have evaluated once daily medications are methodologically flawed and their conclusions dubious.

ABPM has also been valuable in the evaluation of several studies of life-style intervention.

Cost benefit analysis

A recent review concluded that 'Limited clinical applications of ABPM and blood pressure self-measurement in the diagnosis and management of hypertension appear

to be warranted. Endorsement of these technologies for routine clinical use, however, will require more convincing evidence of their clinical effectiveness'.8 This

review also suggested that if ABPM was in routine clinical use to diagnose and monitor all hypertensive patients, at a cost of $120.00 per service, its yearly cost could be $40 million. Clearly, financial considerations have been a factor in ABPM not yet being assigned a Medicare Benefit number. However, if at least $260 million is currently being spent on hypertensive drugs, the identification of up to 20% of patients with 'white coat' hypertension who may currently be on drug treatment and who may not need treatment, could make even widespread use of ABPM cost-neutral.

Reduced visits to the doctor for these patients and improved wellbeing would be additional benefits. As more data on ABPM accumulate, a more informed decision on its cost-benefit will be possible. Clearly, the medical profession must use such a resource responsibly. One method that could minimise costs is the greater use of self-home blood pressure monitoring, particularly in patients where sleeping pressures are not necessary. Simple to operate automatic devices are now available and are currently being evaluated and, in particular, being compared to ABPM.

 

What is a 24 Hour Ambulatory Blood Pressure Monitor ?

An Ambulatory Blood Pressure Monitor is a small device, no larger than a mobile phone, which is used to regularly measure and record blood pressure over a 24 hour period. It is a simple, effective method of monitoring your Blood Pressure over an extended period.

How should I prepare for 24 Hour Ambulatory Blood Pressure Monitor test ?

              As you wear the Blood Pressure Monitor continuously for a 24 hour period and as it is an electronic device which cannot get wet, it is beneficial to shower before the Monitor is fitted.

              It is advisable to wear a two piece outfit with a loose top and sleeve while doing the test.

              Please do not use cream or talc on your chest area on the day of the test.

              Take your usual medications (unless your Doctor advises otherwise). Please bring a list of your medications and your referral.

24 hr blood pressure monitor

Why is a 24 Hour Ambulatory Blood Pressure Monitor test done ?

Results from a 24 Hour Ambulatory Blood Pressure Monitor will indicate whether you have high blood pressure and assess the control of your blood pressure over a longer period. One-off Blood Pressure readings may not reveal periods of poorly controlled hight blood pressure. An Ambulatory Blood Pressure Monitor will indicate fluctuations in blood pressure, as readings are taken regularly over a period of 24 hours.

The Monitor automatically inflates the cuff, measures and records blood pressure and heart rate readings half hourly during the day and hourly during the night. This allows evaluation of the efficacy of a medication or how your blood pressure responds during your daily routine.

24 hr blood pressure monitorWhat is involved ?

              To allow our Nurse to fit the Blood Pressure Monitor you will need to remove your blouse or shirt.

              You will have a Blood Pressure Cuff on your arm just above the elbow on your dominant arm for the 24 hours, this is connected to the Monitor.

              The Monitor is stored in a cloth pouch and worn diagonally across your chest for the duration of the test.

              Our Nurse will take the first Blood Pressure reading once the Monitor is fitted.

              Please be careful not to get the Monitor wet. You will not be able to shower while you wear the Monitor, so it is beneficial to shower before the Monitor is fitted.

              Once the Monitor is in place, do not touch or adjust the Monitor.

              You are then ready to wear the Blood Pressure Monitor for a "regular" day - carry on with normal activities.

              The Monitor automatically inflates the cuff, measures and records blood pressure and heart rate readings half hourly during the day and hourly during the night.

              Each time the cuff inflates, relax your arm, letting it hang straight, not bent. Try to keep your arm as still as possible during the reading or the cuff will inflate again until a correct reading is taken.

              Please record your activities and any symptoms (eg headache, dizziness, light headedness, fainting etc.) and the time and duration you experience them in the Event Diary to help the Doctor make a more accurate evaluation. Please also record the circumstances associated with the symptoms.

              Keep the Diary and a pen with you at all times.

              Do not have X-rays taken while wearing the Blood Pressure Monitor.

              The Monitor runs on batteries and, therefore, requires no external power source.

              Having worn the Monitor for 24 hours, please return the Blood Pressure Monitor to reception at Peninsula Cardiology Centre at the specified time.

How long will it take ?

It only takes about 15 minutes to have the 24 Hour Blood Pressure Monitor put on. The patient will return the next day to have the Monitor removed, this should only take 10 minutes. Please bring your completed Diary.

Does it hurt ?

The procedure is not painful, however, you will be aware each time the cuff inflates and some patients find this uncomfortable. The use of the Monitor is safe, it is particularly compact and only worn for 24 hours.