Determining the boundaries of the lungs is of great importance for the diagnosis of many pathological conditions. The ability to percussively detect the displacement of the chest organs in one direction or another allows one to suspect the presence of a certain disease already at the stage of examining the patient without the use of additional research methods (in particular, radiological).
How to measure lung boundaries?
Of course, you can use instrumental diagnostic methods, take an X-ray and use it to evaluate how the lungs are located relative to the skeleton of the chest. However, it is best to do this without exposing the patient to radiation.
The definition of the boundaries of the lungs at the stage of examination is carried out by the method of topographic percussion. What it is? Percussion - a study based on the identification of sounds that occur when tapping on the surface of a person’s body. The sound changes depending on which area the study is in. Above the parenchymal organs (liver) or muscles, it turns out to be deaf, above the hollow organs (intestines) it is tympanic, and above the lungs filled with air it acquires a special sound (pulmonary percussion sound).
This study is carried out as follows. One hand is placed with the palm of the hand on the study area, two or one finger of the second hand is struck on the middle finger of the first (plessimeter), like a hammer on the anvil. As a result, you can hear one of the options for percussion sound, which was already mentioned above.
Percussion is comparative (sound is evaluated in the symmetrical areas of the chest) and topographic. The latter is just designed to determine the boundaries of the lungs.
How to conduct topographic percussion?
The finger-pessimeter is installed at the point from which the study begins (for example, when determining the upper border of the lung from the front surface, it begins above the middle part of the clavicle), and then moves to the point where this measurement should approximately end. The boundary is defined in the area where the pulmonary percussion sound becomes dull.
For convenience, the finger-pessimeter should lie parallel to the desired boundary. The displacement step is approximately 1 cm. Topographic percussion, in contrast to the comparative one, is performed with a gentle (quiet) tapping.
Upper bound
The position of the tops of the lungs is evaluated both in front and behind. The clavicle serves as a guide on the front surface of the chest, and the seventh cervical vertebra (on the back) (it has a long spinous process by which it can easily be distinguished from other vertebrae).
The upper boundaries of the lungs are normal as follows:
- Front above the level of the clavicle by 30-40 mm.
- The back is usually on par with the seventh cervical vertebra.
The study should be performed as follows:
- In front, a pessimeter finger is placed above the collarbone (approximately in the projection of its middle), and then moves up and to the inside, until the percussion sound becomes blunt.
- At the back, the study starts from the middle of the spine of the scapula, and then the finger-pessimeter is shifted up so as to be on the side of the seventh cervical vertebra. Percussion is performed until a dull sound appears.
Displacement of the upper borders of the lungs
The displacement of the borders up occurs due to the excess airiness of the lung tissue. This condition is characteristic of emphysema - a disease in which the walls of the alveoli are over-stretched, and in some cases their destruction with the formation of cavities (bull). Changes in the lungs with emphysema are irreversible, the alveoli swell, the ability to decay is lost, elasticity is sharply reduced.
The boundaries of the human lungs (in this case, the boundaries of the apex) can move down. This is due to a decrease in the airiness of the lung tissue, a condition that is a sign of inflammation or its consequences (proliferation of connective tissue and wrinkling of the lung). The boundaries of the lungs (upper), located below the normal level, are a diagnostic sign of pathologies such as tuberculosis, pneumonia, pneumosclerosis.
Bottom line
To measure it, you need to know the main topographic lines of the chest. The method is based on moving the researcher’s hands along the indicated lines from top to bottom until the pulmonary percussion sound changes to a dull one. You should also know that the front border of the left lung is not symmetrical to the right due to the presence of a pocket for the heart.
In front, the lower boundaries of the lungs are determined by a line running along the lateral surface of the sternum, as well as along a line going down from the middle of the clavicle.
Important axles on the side are three axillary lines — the anterior, middle, and posterior lines, which begin from the anterior margin, center, and posterior margin of the armpit, respectively. Behind the edge of the lungs is determined relative to the line descending from the angle of the scapula, and the line located on the side of the spine.
Displacement of the lower boundaries of the lungs
It should be noted that during breathing the volume of this organ changes. Therefore, the lower boundaries of the lungs are normally shifted 20-40 mm up and down. A persistent change in the position of the border indicates a pathological process in the chest or abdominal cavity.
The lungs are excessively enlarged with emphysema, which leads to a bilateral shift of the borders down. Other causes may be hypotension of the diaphragm and pronounced prolapse of the abdomen. The lower boundary is shifted down from one side in the case of compensatory expansion of a healthy lung, when the second is in a collapsed state as a result of, for example, total pneumothorax, hydrothorax, etc.
The boundaries of the lungs usually move upward due to the wrinkling of the latter (pneumosclerosis), decay of the lobe as a result of bronchial obstruction, accumulation of exudate in the pleural cavity (as a result of which the lung collapses and contracts to the root). Pathological conditions in the abdominal cavity are also able to shift the pulmonary border up: for example, accumulation of fluid (ascites) or air (during perforation of a hollow organ).
The boundaries of the lungs are normal: table
The lower bounds in an adult |
Field of study | Right lung | Left lung |
The line at the lateral surface of the sternum | 5 intercostal space | - |
The line descending from the middle of the clavicle | 6 rib | - |
The line originating from the front edge of the armpit | 7 rib | 7 rib |
The line from the center of the armpit | 8 rib | 8 rib |
Line from the posterior edge of the axilla | 9 rib | 9 rib |
The line descending from the angle of the scapula | 10 rib | 10 rib |
The line to the side of the spine | 11 thoracic vertebra | 11 thoracic vertebra |
The location of the upper pulmonary borders is described above.
Change in body index
In asthenics, the lungs are elongated in the longitudinal direction, so they often fall slightly below the generally accepted norm, ending not in the ribs, but in the intercostal spaces. For hypersthenics, in contrast, a higher position of the lower border is characteristic. Their lungs are wide and flattened in shape.
How are the pulmonary borders in a child?
Strictly speaking, the boundaries of the lungs in children practically correspond to those in an adult. The tops of this organ in children who have not yet reached preschool age are not determined. Later, they are detected in the front 20-40 mm above the middle of the clavicle, behind - at the level of the seventh cervical vertebra.
The location of the lower boundaries is described in the table below.
The boundaries of the lungs (table) |
Field of study | Under 10 years old | Over 10 years old |
Line from the middle of the clavicle | Right: 6 rib | Right: 6 rib |
Line originating from the center of the armpit | Right: 7-8 rib Left: 9 rib | Right: 8 rib Left: 8 rib |
The line descending from the angle of the scapula | Right: 9-10 rib Left: 10 rib | Right: 10 rib Left: 10 rib |
The reasons for the displacement of pulmonary borders in children up or down relative to normal values are the same as in adults.
How to determine the mobility of the lower edge of the organ?
It has already been said above that when breathing, the lower boundaries shift relative to normal values due to the expansion of the lungs on inhalation and a decrease on exhalation. Normally, such a shift is possible within 20-40 mm up from the lower border and the same down.
The determination of mobility is carried out along three main lines starting from the middle of the clavicle, the center of the armpit and the angle of the scapula. The study is carried out as follows. First determine the position of the lower border and make a mark on the skin (you can use a pen). Then the patient is asked to take a deep breath and hold his breath, after which they again find the lower boundary and make a mark. And in conclusion, determine the position of the lung with maximum exhalation. Now, focusing on the marks, we can judge how the lung moves relative to its lower border.
In some diseases, lung mobility decreases markedly. For example, this occurs with adhesions or a large amount of exudate in the pleural cavities, loss of elasticity by the lungs with emphysema, etc.
Difficulties in conducting topographic percussion
This research method is not simple and requires certain skills, and better - also experience. Difficulties arising from its use are usually associated with improper implementation techniques. As for the anatomical features that can create problems for the researcher, this is mainly expressed obesity. In general, it is easiest to perform percussion on asthenics. The sound is clear and loud.
What needs to be done to easily determine the boundaries of the lung?
- Know exactly where, how and which borders you need to look for. Good theoretical training is the key to success.
- Move from clear to dull.
- The finger-pessimeter should lie parallel to the defined border, but it should be moved perpendicular to it.
- Hands should be relaxed. Percussion does not require significant effort.
And, of course, experience is very important. Practice gives self-confidence.
Summarize
Percussion is a very important diagnostic method of research. It allows you to suspect many pathological conditions of the chest. Deviation of the borders of the lungs from normal values, impaired mobility of the lower edge are symptoms of some serious diseases, timely diagnosis of which is important for the proper treatment.