STETHOSCOPE•The stethoscope(also known as Aala) is an acoustic medical device for auscultation, or listening to the internal sounds of an animal or human body

• It is also used to listen to intestines and blood flow in arteries and veins.

•Construction:-A binaural stethoscope(commonly used) consists of earplugs, binaural pieces, flexible tubing, a stem, and a chestpiece.

:-

•Principle-Stethoscope works on the principle of multiplereflection of sound.

•Working-When a doctor or nurse places a stethoscope diaphragm on a patient's chest, sound waves traveling through the patient's body cause the flat surface of the diaphragm to vibrate. Those vibrations would travel outward, but because the vibrating object is attached to a tube, the sound waves are channeled in a specific direction. Each wave bounces, or reflects, off the inside walls of the rubber tube, a process called multiple reflection. In this way, each wave, in succession, reaches the eartips, or rubber nubs on the ends of the device, and finally the listener's eardrums.

Stethoscope Head Specifications•The head of a stethoscope is the metal end that is placed on the chest to listen to the lungs and heart. The size of an adult stethoscope head is 45mm, while a pediatric head is 35mm. Some stethoscopes have single chest pieces, which mean they are specifically made for either an adult or pediatric patient. However, some have dual heads. These stethoscopes are designed with both chest pieces and can be used for either adults or children. The chest piece is made from surgical stainless steel.

Tube Specifications•The tubing varies on each model. Stethoscopes with tapered inner bores provide a better sound transmission when listening to the heart or lungs. If the stethoscope has extra-thick tubing, outside noise is reduced. You can choose between stethoscopes with a 21-inch single bore flexible tubing or 19-inch two-in-one bi-lumen tubing. The length of the stethoscope can vary from 27 inches to 29 inches. It can weigh between 6 ounces and 7.6 ounces. Tubing can come in black, blue, green, orange, pink and burgundy colors.

Specifications

Type OF Stethoscope:-

•ACOUSTIC stethoscope

o operate on the transmission of sound from thechestpiece, via air-filled hollow tubes, to the listener's ears

o Acoustic stethoscopes are familiar to most people

o Demerit:-Demerit of acoustic stethoscopes was that the sound level is extremely low.

•Electronic stethoscope

oAn electronic stethoscope (or stethophone) overcomes the low sound levels by electronically amplifying body sounds

o The simplest and least effective method of sound detection is achieved by placing a microphone in the chestpiece.

o can be a wireless device, can be a recording device, and can provide noise reduction, signal enhancement, and both visual and audio output.

•Price of stethoscope:- It is vary from ₹300 to ₹ 40,000.

Sphygmomanometer

A sphygmomanometer, blood pressure meter, or blood pressure gage (also referred to as a sphygmometer) is a device used to measure blood pressure.

It is always used in conjunction with a means to determine at what pressure blood flow is just starting, and at what pressure it is unimpeded.

Construction:-A sphygmomanometer consists of an inflatable cuff, a measuring unit (the mercury manometer, or aneroid gauge), and a mechanism for inflation which may be a manually operated bulb and valve or a pump operated electrically.

Working- There are two numbers in a blood pressure reading: systolic and diastolic. When the doctor puts the cuff around your arm and pumps it up, what he/she is doing is cutting off the blood flow with the pressure exerted by the cuff. As the pressure in the cuff is released, blood starts flowing again and the doctor can hear the flow in the stethoscope. The number at which blood starts flowing (120) is the measure of the maximum output pressure of the heart (systolic reading). The doctor continues releasing the pressure on the cuff and listens until there is no sound. That number (80) indicates the pressure in the system when the heart is relaxed (diastolic reading).

If the numbers are too high, it means that the heart is having to work too hard because of restrictions in the pipes. Other things that can increase the blood pressure include deposits in the pipes and a loss of elasticity as the blood vessels age.High blood pressure can cause the heart to fail (from working too hard), or it can cause kidney failure (from too much pressure).For example, a typical reading might be 120/80.

1 Should be Portable mercurial type.

2 Should have ISI mark.

3 Should have ON and OFF provision for mercury reservoir.

4 Should have a measuring range from 0 to 300 mmHg.

5 Should be provided with adult arm cuffs of size medium & large and

paediatric cuff.

6 The control valve should have a knurled thumb control device. The leak rate

should not exceed 10 mm of mercury per minute.

7 The manometer scale markings and graduations should be permanent and

clearly visible and filled with pigments.

8 The internal diameter of the manometer glass tube should be 4.1 ± 0.1 mm

and the thickness not less than 2 mm.

9 All plastic parts, if any used should not crack, flake, peel or disintegrate in

normal use.

10 The inflating rubber bag should be capable of withstanding an internal

pressure of 450 mmHg without leaking.

11 The inflating bulb should be soft and should not have any joints or ridges.

.

Technical Specification

Mercury sphygmomanometers : They are considered to be the gold standard. They measure blood pressure directly by observing the height of a column of mercury; errors of calibration cannot occur

TYPES:-Manual sphygmomanometers : It require a stethoscope for auscultation . They are used by trained practitioners. It is possible to obtain a basic reading through palpation, but this only yields the systolic pressure.

•Aneroid sphygmomanometers (mechanical types with a dial) are in common use;they require regular calibration checks, unlike mercury manometers. Aneroidsphygmomanometers are considered safer than mercury based, although less accurate. A major cause of departure from calibration is mechanical jarring. Aneroidsmountedon walls or stands are less susceptible to this particular problem.

•Digital: Digital sphygmomanometers are automated, providing blood pressure readingwithout needing someone to operate the cuff or listen to the blood flow sounds. However digital types are less accurate. Some healthcare providers use digital forscreening but use manual sphygmomanometers to validate readings in some situations.

Price:-The price of sphygmomanometer vary from ₹ 600 to ₹ 6000.