Why do lungs ‘wheeze’? Scientists tried to find out

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  • Many conditions affecting the respiratory system can cause wheezing
  • However, scientist do not know the physical mechanisms behind wheezing
  • But now, a new study offers some insight into what causes our lungs to make this raspy sound

Whether you’re an asthmatic, get hay fever, or just have a really bad respiratory infection – most of us have experienced the raspy sound known as wheezing.

While medical practitioners have been using wheezing as a diagnostic tool for a long time, experts reveal that they do not know the true mechanism behind the sound.

A new study led by the University of Cambridge sought to address this knowledge gap by modelling the lung passages in an attempt to better understand the physical mechanism behind wheezing.

Getting to the bottom of wheezing 

A team of scientists from the Department of Engineering at the University of Cambridge designed and built a lung by adapting a device known as a Starling resistor. “We model the airways of the lungs by a modified Starling resistor in which airflow is driven through thin, stretched elastic tubes,” the researchers wrote in their paper.

They then completed a series of systematic experiments in order to see under which conditions wheezing is initiated and how it is sustained. This led to the finding that there is a “violent” process that causes the lungs to wheeze. 

“It surprised us just how violent the mechanism of wheezing is,” said researcher Alastair Gregory.

“We found that there are two conditions for wheezing to occur: the first is that the pressure on the tubes is such that one or more of the bronchioles nearly collapses, and the second is that air is forced through the collapsed airway with enough force to drive oscillations.”

'Tube law'

Upon completing the experiments, the researchers expressed that they found a generalised “tube law” that takes into account the pressure the tubes are under as well as the cross-sectional area of the tubes, in order to determine the onset of oscillations that represent wheezing.

If the law can be tweaked to be applied to human lungs, it can be used as a means to analyse wheezes and also help with diagnosing serious bronchial problems. 

“Our findings allow for a predictive tool for wheezing in lungs, which could lead to better diagnosis and treatment of lung diseases,” the researchers concluded. 

Image credit: Pixabay

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