A stethoscope serves as a valuable tool that amplifies internal body sounds, allowing for a basic assessment of various bodily functions. By enhancing these sounds, a stethoscope aids in understanding the rhythmic patterns of the heart, the flow of air in the lungs, and the movements within the digestive system.
Listening Points for the Heart
To listen to the heart’s activity, specific locations on the chest provide the clearest sounds. These primary points correspond to where the sounds of the heart valves are best heard, rather than directly over the valves themselves.
The aortic area is on the right side of the sternum, in the second space between the ribs. Moving across to the left side of the sternum, in the second intercostal space, is the pulmonic area.
Just below the pulmonic area, in the third intercostal space on the left side of the sternum, lies Erb’s point, where both primary heart sounds can often be heard. Further down the left side of the sternum, in the fourth intercostal space, is the tricuspid area. Finally, the mitral area, also known as the apex, is in the fifth intercostal space on the left side, typically aligned with the middle of the collarbone.
At these points, one listens for the characteristic “lub-dub” sounds, which represent the closure of the heart valves during the cardiac cycle. The “lub” (S1) sound is caused by the closing of the mitral and tricuspid valves, while the “dub” (S2) sound results from the closing of the aortic and pulmonic valves.
Listening Points for the Lungs
Listening to lung sounds involves systematically covering areas on both the front and back of the chest to assess air movement. On the front, begin above the collarbones to listen to the upper lung portions.
Moving downwards, the stethoscope is placed in a ladder-like pattern, comparing sounds from one side of the chest to the other at each level. It is important to avoid placing the stethoscope directly over the sternum or breast tissue, which can muffle sounds.
For the back of the chest, the listener starts at the top, just above the shoulder blades, and proceeds downwards in a zigzag pattern, moving from side to side. The shoulder blades should be avoided, as listening over bone can obscure lung sounds; sometimes, having the individual cross their arms can help move the shoulder blades out of the way. Additionally, lateral areas of the chest, under the arms, are also examined to assess all lung lobes. At each position, listen through one complete breath cycle to hear air flow clearly.
Listening Points for Abdominal Sounds
When assessing digestive system sounds, the abdomen is divided into four imaginary regions: the right upper, right lower, left upper, and left lower quadrants. Listening for bowel sounds involves placing the stethoscope in each quadrant.
It is common practice to begin in the right lower quadrant, as bowel sounds are often most active there due to the ileocecal valve. From this starting point, one then proceeds in a clockwise direction to the right upper, left upper, and finally, the left lower quadrant.
Listening in these areas detects the movement of fluid, gas, and contents through the intestines. Normal bowel sounds are typically described as irregular gurgling or clicking noises. These sounds occur intermittently, often every 5 to 15 seconds, and their intensity and frequency can vary throughout the day, particularly after meals. Listening for a minute or more in each quadrant helps to determine the presence and character of these sounds.
Listening Points for Blood Pressure Measurement
When manually measuring blood pressure, precise stethoscope placement is important for detecting specific sounds. The stethoscope is positioned over the brachial artery, which is located in the antecubital fossa, or the inner bend of the elbow. To find this artery, one can often feel for a pulse in this area. Once located, the diaphragm of the stethoscope is placed gently but firmly over the artery.
This placement allows the listener to hear Korotkoff sounds, which are the distinct noises produced by the turbulent flow of blood through the artery as a blood pressure cuff is deflated. The first sound heard indicates the systolic blood pressure, and the point at which the sounds disappear marks the diastolic blood pressure. The stethoscope is used with a blood pressure cuff, wrapped around the upper arm a few centimeters above the elbow crease.