Demonstration of Blood pressure by Digital meter

 Experiment Demonstration of Blood Pressure by Digital meter 

Principle: A digital BP monitor uses an inflatable air-bladder cuff, a battery-powered air pump and a pressure sensor for sensing arterial wall vibrations to measure blood pressure in an artery. This is known as oscillometric method. 

The 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. 

[ There are two types of digital BP monitors: the upper-arm  and the wrist models. The upper-arm model has a cuff that is placed on the upper arm and is connected by a tube to the monitor that rests on a surface near the arm. The wrist model is smaller and the entire unit wraps around the wrist. Regardless of the BP monitor type, the measurement method is the same.]

Working Technique Digital blood pressure monitor uses an air pump to inflate a cuff surrounding an upper arm or a wrist with sufficient pressure to prevent blood flow in the local main artery. This pressure is then gradually released using a digitally-controlled solenoid valve until the moment that the blood begins to flow through the artery.

The blood pressure measured by a pressure sensor at this point determines the systolic pressure. Pulse rate is also sensed at this time. The measurement taken when the blood flow is no longer restricted determines the diastolic pressure. 

This complete measurement cycle is controlled automatically by the micro-controller. The signal from the pressure sensor is conditioned with an instrumentation amplifier before data conversion by an analog-to-digital converter (ADC). 

The systolic pressure, diastolic pressure, and pulse rate are then calculated in the digital domain using an algorithm appropriate for the type of monitor and sensor utilized. The resulting systolic, diastolic, and pulse-rate measurements are displayed on a liquid-crystal display (LCD), time-stamped, and stored in non-volatile memory.

Procedure:

For Resting phase

1. Make the subject sit in a comfortable place to sit with good back support at a table or desk quietly for three to five minutes beforehand.

2. Place subject's feet flat on the floor and rest their arm on a tabletop even with their heart. Let them lean against the back of the chair. Stretch out arm, palm upward.

3. Place the cuff on their bare upper arm one inch above the bend of the elbow. Make sure the tubing falls over the front centre of the arm so that the sensor is correctly placed. Pull the end of the cuff so that it's evenly tight around the subject’s arm.

4. Place it tight enough so that you can only slip two fingertips under the top edge of the cuff. Make sure the skin doesn't pinch when the cuff inflates.

5. Wait a moment, then press start. Subject should remain still and quiet as the machine begins measuring. The cuff will inflate, then slowly deflate so that the machine can take measurement. When the reading is complete, the monitor displays your blood pressure and pulse on the digital panel. If the monitor doesn't record a reading, reposition the cuff and try again.

6. Let subject rest quietly and wait about one to two minutes before taking another measurement.

After working out/Exercise

7. After taking three measurements at resting phase, ask the subject to moderately exercise for 10minutes. ( Walk or Run in a treadmill/ Climb up and down status/ do push ups). Repeat the steps 2 to 5 for recording blood pressure after mild to moderate exercise and note the difference between resting and active phase.

Result

Sl. No.	Name	Resting Systolic BP (A)	Resting Diastolic BP (B)	Resting Pulse pressure (A-B)	Resting Pulse rate	Workout Systolic BP (A')	Workout Diastolic BP (B')	Workout Pulse pressure (A”-B’)	Workout Pulse rate	Remarks
1	x	126	82	44	65	140	90	50	78
2	y	120	80	40	60	152	80	72	71

Precaution:

Any pre-existing health condition is to be taken under consideration for Exercise experiment.