Parts of a Stethoscope
Doctors are aware of the intensity, quality, or pitch of sounds that is normally associated with certain parts of the body. If they hear any variation from the normal sounds, they can perform other diagnostic tests to confirm the diagnosis. A stethoscope helps the doctors ascertain the presence and location of abnormal sounds. At times, the absence of sounds could help in the diagnosis. For instance, the absence of bowel sounds can be an indicator of bowel problems.
The components of a stethoscope include:
✦ Binaurals (ear tubes or curved metal pipes that connect the earpieces to the tubes of stethoscope)
✦ Air-filled tube
✦ Chest piece
The headset comprises the two earpieces and ear tubes. The chest piece consists of a bell and a diaphragm. While the bell is the cup-shaped side that is used for listening to low frequencies or low-pitched sounds, the diaphragm is the flatter side that is used for high frequencies. A removable chill ring prevents the chest piece from coming in contact with the skin, and also keeps the diaphragm in place. In case of dual-frequency, tunable stethoscopes, the bell and the diaphragm are combined on one side of the chest piece. All the user needs to do is apply varying pressure to listen to low or high frequencies. Low pressure and high pressure needs to be applied to listen to low frequency and high frequency sounds, respectively.
In case of the two-sided chest piece, the user can switch between the bell and the diaphragm, depending on the frequency. It must be noted that only one part of the chest piece can work at a time. The sound can be amplified either through the bell or the diaphragm. If the sound is barely audible through the bell, it implies that the diaphragm is in the position for use. There are certain types of stethoscopes that don’t have a bell.
When the diaphragm is placed on the skin, it vibrates due to the sounds from the body. This leads to the creation of the acoustic pressure waves, which in turn travel up through the tube. The sound is transmitted from the bell or the diaphragm to the earpieces, which fit in snugly in the ears, thereby preventing other sounds from entering the ears.
How to Use a Stethoscope Properly
There are a few aspects that you need to keep in mind in order to use a stethoscope properly. Basically, you need to put the earpieces in such a way that they create an airtight seal with the ears. This is to block the noises from the outside environment, so that you can focus or clearly listen to the sounds emanating from the internal organs. Here are a few pointers on using a stethoscope in a correct way:
✦ After placing the earpieces in the ears, adjust them so that they point slightly forward. Usually, binaurals or the ear tubes are positioned at an angle of 15°, so that earpieces can point forward and align with the ear canal. Ensure that the earpieces are a snug fit.
Eartips should be a perfect fit
✦ If you have placed the earpieces properly, the external noise will become faint. Earpieces are available in small, as well as large sizes. So, make sure that you opt for a size that is a perfect fit.
✦ Make sure that you check the earpieces on a regular basis. Look for cracks. Also, it is essential to clean the earpieces, so that auscultation is not affected by the accumulation of earwax, lint, or dirt.
Don’t place the fingertips on the edge of the diaphragm/bell
✦ The chest piece should also be held in the right manner. It must be held between the index finger and the middle finger of the dominant hand. Fingertips should not be placed on the edge of the diaphragm or bell, as that can lead to noise, which in turn will affect one’s ability to listen to the sounds from the internal organs. Make sure that the stethoscope tube doesn’t rub against the patient’s skin.
Double-sided stethoscope with a bell and diaphragm
✦ If you are using a double-sided stethoscope that has a bell and diaphragm, you will need to rotate the chest piece, so as to open the bell or diaphragm. If the diaphragm is open, the bell will be closed, and vice versa. This is to ensure that sound doesn’t come through the other part. This prevents noise interference, thereby allowing doctors to hear high or low frequency sounds properly.
✦ If you are using a tunable stethoscope, move the chest piece in a half circle. Once you hear a click, tap the bell and diaphragm to check which one of them is open.
✦ Make sure that the parts of the chest piece are not loose. Look for signs of damage.
✦ Do not touch the tube (tube that runs from the chest piece to the headset) while examining a patient with a stethoscope.
Place the stethoscope on bare skin to minimize noise interference
✦ Placing the diaphragm or the bell on bare skin would also help avoid noise interference that could occur due to the mixing of sounds from the body and clothes.
On a concluding note, it is essential to clean the stethoscope to ensure optimal acoustical performance, as well as reduce the risk of transmission of pathogens. It is advisable to disinfect the bell/diaphragm of the stethoscope before using it on another patient. It can be wiped with a 70% isopropyl alcohol solution. Also, make sure that it is not exposed to extreme temperature, solvents, and oils. Remove the earpieces from the tubes regularly for thorough cleaning.