Tracheal breathing
In one sentenceA harsh, loud, broadband sound heard over the neck, with a prominent expiratory component.
Listen to the same sound in another patient. Breathing rate, chest wall, the pitch of the sound and the number of adventitious sounds vary within realistic limits.
What does it sound like?
Both phases are loud. High-frequency components are prominent. There is a short silence between the phases.
Where is it heard?
At and just above the suprasternal notch, along the trachea.
What causes it?
The sound arises in the larynx and trachea, just beneath the stethoscope. No lung lies in between, so it is not filtered. It is loud, harsh and high-pitched. The shape of the upper airway shapes the sound. In tall people it is a little lower in pitch.
Quantitative criteria
- Compared with the chest wall sound, it is more broadband, stronger at high frequencies and much larger in amplitude.
- It is a particularly suitable recording site for respiratory timing and respiratory rate.
Clinical meaning
It is used for respiratory rate monitoring, acoustic flow estimation, snoring and sleep apnoea screening, apnoea detection during sedation, and stridor. The tracheal sound is not an "unfiltered lung sound". It carries the acoustics of the upper airway itself.
Sounds it can be confused with
Stridor is a loud musical tone superimposed on the tracheal sound. It is mostly inspiratory.
A sound of the same character heard in the periphery is bronchial breathing.
To tell stridor from a wheeze, listen first over the neck and then over the chest. Stridor is much louder over the neck.
See the reference list for sources.