Blood Pressure Monitor

Blood pressure monitor: 

Blood pressure is one of the important physiological variables within the human body, its rise or fall is an indicator of the state of the heart cycle, which means all accidents associated with one heartbeat.

Blood pressure: 

Pressure is the force acting on a unit area, it is directly proportional to the force and inversely to the area ،Blood pressure is formed as a result of contraction of the walls of the ventricular muscles.

Pressure in the physiological sense is: pressure in the four cavities of the heart during contraction and diastole and inside the arteries, veins and capillary vessels.

What does blood pressure depend on: 

  1.  Cardiac subtraction: It is the amount of blood paid from the ventricles per minute.
  2. The resistance surrounding the walls of blood vessels: Whenever the diameter of the vessels is less than normal, this will cause high blood pressure
  3. Rubber and elasticity of the walls of blood vessels: as the vessels of little elasticity cause an obstacle to the passage of blood and thus raise blood pressure.
  4. The volume of blood in the blood vessels.
  5. Blood viscosity: The higher the viscosity of the blood, the higher the blood pressure.

Types of blood pressure: 

  1. Venous pressure: It is the pressure of the veins.
  2.  IPL pressure: It is the pressure of small capillaries.
As for the term blood pressure: it represents the pressure of the arteries and is divided into two types:

  1.  Systolic pressure: It is the amount of pressure during the pumping of blood outside the heart and the normal range of (110 to 130) mm Hg.
  2. Diastolic pressure: It is the pressure affecting the walls of the pulmonary blood vessels and its pressure is little because it is limited to the lung only and the normal range is from (70 to 80) mm Hg.

Methods of measuring blood pressure: 

There are two ways to measure blood pressure in the human body:

 Indirect method: 

It is the method of measurement from outside the human body using a blood pressure monitor, and this method is safe and easy to use.

 There are two types of: 

 Mercury blood pressure monitor consisting of the following parts: 

  1.  Digital ruler.
  2. Tube.
  3.  Inflatable air bag (collar).
  4. Mercury tank.
  5. Mercury.
  6. Rubber blower (rubber hand pump).
  7. Valve under the blower and the blower gate.
  8.  Metal vase.
  9. Valve above the tank.
  10. Rubber tubes.
  11. Stethoscope.

 How to use the device: 

The theory of the device's work is focused on placing the collar on the patient's arm and we start filling the collar with compressed air by the manual blower until we block the artery and then the blood flow will stop because the blood does not flow unless the pressure of the collar is less than the pressure of the artery and the blood flow is heard by a stethoscope that is placed on the artery, and then the valve is opened to gradually reduce the pressure inside the collar and when the pressure of the collar reaches less than the pressure of the artery, it begins to hear the pressure of contraction Which is the biggest pressure ، And the normal range for humans (120/80) where 120 systolic pressure and 80 diastolic pressure.

Possible device malfunctions: 

  1.  Blackening of mercury (oxidation of mercury).
  2. The appearance of air bubbles in the mercury pipe as a result of its quantity.
  3. The appearance of dents in the blower or rubber bag.

Automatic electronic blood pressure monitor: 

This method is used in the emergency department, intensive care units and cardiac care, where accuracy is required in measuring pressure and this method differs in that it uses an automatic pump to the air collar with an electronic transducer instead of a stethoscope. 

It includes the following parts:

  1. Blower and rubber bag.
  2. A transducer that converts mechanical energy into an electrical signal.
  3. Pressure amplifier.

 How to use the device: 

  1.  The collar is filled with air by an automatic pump to pressure the artery until the air pressure becomes higher than the pressure of the artery, then the pump is automatically extinguished.
  2. After that, an electronic transducer senses any pressure in the artery through the principle of vibration.
  3.  After completing the measurement, the air is leaked through the drain valve and this reading is recorded using the microprocessor, stored and displayed on the screen.

 Direct method:

We talked in the previous paragraph that the indirect blood pressure measurement method is easy to use and safe, but there are some disadvantages as it cannot record changes in pressure at the same time, in addition to that it only measures the pressure of the artery as numerical values and not as a detail of the pressure waveform, and we cannot measure vein pressure using this method. 

Direct measurement of blood pressure means measurement inside the human body and where this method is distinguished compared to the indirect method thus: 

  1. Accuracy in reading pressure.
  2. Ability to measure very low pressure readings 
  3. The ability to measure continuously and thus be able to obtain the form of a pressure wave and also follow the pressure change.

But it also has disadvantages of the direct method: 

  1.  There is a danger to the patient to use substances inside the body.
  2.  More expensive compared to the indirect method.
  3. You need high skills, especially in the measurement process, unlike the indirect method, so that anyone measures the pressure for its ease.
  4.  It takes longer to prepare and use the meter.

There are three ways to measure blood pressure in a direct way: 

  1. Catheter: It is a thin flexible tube that passes through the artery or vein.
  2.  Placing a transducer inside the artery by opening it in the skin.
  3. Implantation of a transducer inside the artery, vein or in the heart.


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