Nasal Physiology and Physics
Nasal Diameter- Why it Matters So Much
It seems peculiar why a small change in the airway has so a big impact on how breather. If we compare the nose to a tube, there is an applicable principle termed the Poiseuille Equation.
From this equation we can see that if the airway is slightly larger, it will have a much larger impact on the nasal airflow. An example if the radius of the nose went from 1 cm to 2 cm, the airway would open up not just twice but 16 times. An analogy of how a small change in airway diameter can impact breathing is to compare breathing from a straw to a snorkel. A straw has a smaller airway and it is possible to breathe under water with it. However, with faster swimming and every so often a swimmer will need to raise their head above water to breathe. A snorkel allows the swimmer easier and more fluid breathing. Small airways collapse more likely
Another reason why a relatively smaller airway is more likely to collapse is due to another physics principle called Bernoulli's principle. This principle states that when you breathe through a pipe with various sizes, the flow is fastest through the narrowest portion. Why is faster airflow an issue? First of all, think of a shower curtain. With faster airflow inside the shower, relative to outside the shower, the curtain collapses in the inside of the shower due to this principle. In a nasal airflow analogy, when the nose is narrowed in specific areas, such as near the septum or a narrow nasal valve, the faster airflow can create a similar effect collapsing the nasal airway.
Surgeon's who understand the physics of the nose can better understand how to treat it. In some cases, this may mean opening a nasal airway from an obstructed portion of septal cartilage. In other cases, this may mean either widenening or supporting a nasal airway to support it.