The passage of air through the trachobronchial tree creates a characteristic set of noises that are sudible through the chest wall. These nosies also may be modified by obstruction within the respiratory passages or by changes in the lung parenchyma, the pleura or the chest wall.
Breath sounds: evaluate the presence and quality of normal brath sounds. The person is sitting, leaning forward sligtly with arms resting comfortably across the lap. Instruct the person to breathe throught he mouth a little bit deeper than usual but to sto if he or she feels dizzy. Be careful to monitor the breathign throughout the examination and offer times for the person to rest and breate normally. The person is usuallyw illing to comply with your instructions in an effort to please you and be a good patient. Watch that he or she does not hyperventialte to the point of fainting.
Clean the flat diaphragm endpiece of the stethoscope and hold it firmly on the sperson's chest wall. Llisten to at least one full respiration in each location, side to side comparison is most important.
Do not confuse background noise with lung sounds. Become familiar with these extraneous noises that may be confused with lung pathology if not recognize.
1. Examiner's breathing on stethoscope tubing
2. Stethoscope tubng bumping together
3. Patient shivering
4. Patient's hair chest: movment of hairs under stethoscope sound like crackles (rales) minimze this by pressing harder or by wetting the hair with a damp clothh
5. Rusting of paper grown or paper drapes
While standing behind the person listen to the following lugn areas--posterior from the apeices at C7 to the bases (aroudn T10), and laterally from the axilal down to the seventh or eigth rib.
Continue to visualize approximate locations of the lobes of each lugn so that you correlate your findings to anatomical areas. As you listen think 1 what am I hearing over this spot and 2 what should I expect to be hearing? You shuould expect to hear three types of normal breath sound sin the adult and older child: bronchial, sometimes called tracheal or tubular), bronchovesicular, and vesicular. Crackles are abnormal lung sounds.
Note the normal location of the three types of breath sounds on the chest wall of the adult and older child.
Decreased or absent breath sounds occur:
When the bronchial tree is obstructed at some point by secretions, mucus plug or a foreign body.
In emphysema as a result of loss of elasticity in the lung fibers and ecreased force of inspiraed air; also the lugnsa are already hyperinflated so the inaled air does not make as much noise
When anything obstructs transmission of sound between the lung and your stethoscope, such as pleurisy or plerual thickening or air (pneumothroax) or fluid (pleural effusion) in the pleural space.
A silent chest means no air is moing in or out, which is an ominous sign.
Increased breath sounds: mean that sounds are louder than they should be (eg. Bronchial sounds are abdominal when they are heard over the abdominal location, the peripheral lung fields)> they have a high pitched, tubular quailty, with a prolonged expiratory phase and a distinct pause between inspiration and expiration> They sound very close to your stethoscope, as if they were right in the tubing close to your ear. They occur when consolidation (eg pneumonia) or fcompression 9eg fluid in the intraplerual space) yeilds a dense lung area that enhances the transmission of sound from the bronchi When the inspired air reaches the alveoi it hits solid lung tissue that conducts sound more efficiently to the surface.
Adventitious sounds: note any adventitious sound.s These are added sounds that are not normally heard in the lugs. If present, they are heard as being superimposed on the breath sounds. They are caused by moving air colliding with secretions in the trachobronchial passageway or by poppign open of previously deflated airways. Sources differ as to the classification and nomenclature of these sounds, but crackles (or rales) and wheeze (or rhonchi) are the terms most common ly used by examiners
One type of adventitious sound, atelecatatic crackles, it is not pathologic. They are short, popping, crackling sounds that sound like fine crackles but do not last beyond a few breaths. When sections of alveoi are not fully aerated 9as in people awho are asleep or in older adults), they deflate sligtly and accumulate secretions. Crackles are heard when these secretions are expanded by a few deep braths. Atelectatic crackles are heard only in the periphery, usually in dependent portions of the lugns and disappear after the first few breath or after a cough.
In the past persons were asked to "take a deep rbeath and blow it out hard" to screen for the presence of wheezing. However, this manuver is futile because evidence hsows wheezing may occur on maximal forced exhalation in healthy people.
During normal tidal flow, high pitched wheeze occurs with asthma.
Voice sounds: Determine the quailty of voice sounds or vocal resonance. The spoken voice can be ausculated over the chest wall just as it can be felt in tactile fremitus described earlier. Ask the person to repeat a phrase such as "nignety nine" while you listen over the chest wall. Normal voice transmission is soft, muffled and indistinct; you can hear sound through the stethoscope but cannot distinguish exactly what is being said. Pathology that increases lung density enhanses transmission of voice sounds.
Eliciting the voice sound is not done routinely. Rather these are supplemental manuvers performed if you suspect lung pathology on the basis of earlier data. Whn they are performed you are testing formt te possibel presence of bronchophony, egophony and whispered pectoriloquy.
Consolidation or compression of lung tissue will enhance the voice sounds, making the words more distinct.