Scattered short wheezes
In one sentenceShort single-tone wheezes at different pitches in each expiration; common in asthma.
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?
One, two or three short wheezes are heard in expiration. Each has a single tone, but their pitches differ. Their timing and pitch change from breath to breath.
Where is it heard?
Widespread over the chest; different tones may be heard at different points.
What causes it?
In widespread but uneven narrowing, different airways vibrate at different moments. Each produces its own tone for a short time; as flow and pressure change, one falls silent and another begins.
Quantitative criteria
- In recordings from 41 adult patients (KAUH, CC BY 4.0), a single wheeze lasted a median of 0.55 s (most 0.4–0.8 s); the starting pitch was mostly between 210 and 390 Hz.
- On the spectrogram, short lines at different heights follow one another in expiration. The lines mostly fall; flat or rising lines also occur. Because the tones are heard one after another rather than together, they differ from a polyphonic wheeze.
Clinical meaning
This is a common pattern in asthma; Forgacs linked random monophonic wheezes to widespread airway disease. If the same tone keeps recurring at the same place, think of a local narrowing and assess it as a fixed monophonic wheeze.
Sounds it can be confused with
In a fixed monophonic wheeze, the same pitch is heard at the same place every time.
In a polyphonic wheeze, several tones are heard at the same time.
Listen over several breaths: if the pitch and place change, think of random wheezes; if they stay the same, think of a fixed monophonic wheeze.
See the reference list for sources.