Fremitus is a vibration transmitted through the body.
In common medical usage, it usually refers to assessment of the lungs by either the vibration intensity felt on the chest wall (tactile fremitus) and/or heard by a stethoscope on the chest wall with certain spoken words (vocal fremitus), although there are several other types.
Feeling the vibrations generated from the spoken voice is termed tactile fremitus,
- Is evaluated by having the patient say “ninety-nine” or “one-two-three”, and feeling the transmitted vibrations with the hands.
- Is more prominent in the interscapular regions, less prominent at the lung bases.
- Provides information about the density of underlying lung tissue and chest cavity.
- Is decreased or absent in conditions that impede transmission of sound (such as an obstructed bronchus, COPD, pleural fluid, or a very thick chest wall).
- Is increased in conditions that increase transmission of sound (such as consolidated lobar pneumonia).
An increase in tactile fremitus indicates denser or inflamed lung tissue, which can be caused by diseases such as pneumonia. A decrease suggests air or fluid in the pleural spaces or a decrease in lung tissue density, which can be caused by diseases such as chronic obstructive pulmonary disease or asthma.
Evaluating speech through the stethoscope is termed vocal fremitus, when a person speaks, the vocal cords create vibrations (vocal fremitus) in the tracheobronchial tree and through the lungs and chest wall, where they can be felt (tactile fremitus).
This is usually assessed with the healthcare provider placing the flat of their palms on the chest wall and then asking a patient to repeat a phrase containing low-frequency vowels such as “blue balloons” or “toys for tots” (the original diphthong used was the German word neunundneunzig but the translation to the English ‘ninety-nine’ was a higher-frequency diphthong and thus not as effective in eliciting).
- Is evaluated by having the patient say “ninety-nine” while listening with the stethoscope over various portions of the lungs.
- Is an indistinct low-pitched mumble over normal lung.
- Is increased over areas where the lung has become airless (e.g. consolidation or atelectasis) and results in louder, clearer voice sounds (bronchophony).
- Is particularly notable if the patient whispers a message, and it is clearly audible through the stethoscope over the airless portion of lung (whispered pectoriloquy).
- Is decreased when there is a decrease in lung density such as hyperinflation, or focally when the lung tissue is separated from the chest wall (for example in pneumothorax or pleural effusion).
- When voice sounds increase in intensity and take on a “bleating” quality, this is described as egophony. Egophony is present when “e-e-e” spoken by the patient is heard through the stethoscope as “a-a-a.” Egophony is generally found over consolidated lung where bronchophony is also present.
These signs are most easily appreciated when various areas of lung are compared to each other.
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