The Physiologic Disturbance of Asthma–What’s that all about?


bronchioles

Physiologic means function. In the case of asthma, it means function of your airways.

Disturbance simply means an abnormality.

So “physiologic disturbance” is an abnormality that causes the airways to not function correctly. The function of the airways is to let air flow in and out of the lungs. That’s an important function!

Asthma is a specific physiologic disturbance—a specific airway dysfunction. But the definition of “asthma” that most doctors and medical societies use these days is no longer focused on physiology (function), and this has led to substantial confusion as well as misdirection of research money and intellectual resources. I would ask you instead to join me in a definition of asthma that I prefer. This definition is absolutely central to my philosophy of asthma.

 

The definition I find most useful for asthma is this: recurrent episodes of reversible airflow limitation in the chest.

 

Let’s parse that.

Recurrent: The episodes happen repeatedly.

Reversible: An airflow limitation goes away with time or with medication.

Airflow limitation: Air cannot move through the tubes within the lungs as well as it should.

In the chest: It needs to be in the chest. There are airways above the chest that can make noises too, but those noises aren’t asthma (although they can be confused with asthma easily).

 

It is the airflow limitation that causes a child to have the symptoms of asthma. Or, if the airflow limitation is above the lungs, can cause symptoms that are confused with asthma. It is the recurrent and reversible components that distinguish asthma from lung diseases that cause breathing difficulties, such as pneumonia (which is acute and not recurrent) and emphysema / chronic bronchitis (which is persistent as opposed to recurrent, and the airflow limitation is not reversible).

 

This definition of asthma that I choose is the definition doctors used fifty years ago. It was the right definition then, and I am convinced it still is now. In a later post, I will present the modern definition that I think has kinda messed up doctors’ thinking about asthma. Modern medications for treating children who have asthma are miraculous. Modern definitions for asthma are not so good.

 

Again, my preferred definition of asthma is recurrent episodes of reversible airflow limitation in the chest.

 

For now, let’s take a moment for a brief experiment, please.

 

Open your mouth wide, keep it open, and blow.

Please, go ahead and do it. Give it a big, open-mouthed blow.

 

When you do that, you huff, but there is no whistle.

Now compare that to when you purse your lips and blow, and intentionally whistle. The narrow hole through your lips causes the whistle.

 

Wheezing (which you may know well if you have a child with asthma) results from airways that are narrowed enough to make whistling sounds. Usually during asthma exacerbations (a term used for acute worsening of asthma) there are lots of airways all making whistling sounds at the same time. This is wheezing. It is the difference between a normal airway (like your wide open mouth) and a narrow airway (like your pursed lips when you whistle).

Wheezing that results from any of the common forms of asthma should be heterophonous, meaning you can hear multiple different pitches all at the same time. It can sound like the string section of an orchestra tuning up before embarking on playing the theme from Star Wars. High pitches, low pitches, wiggly pitches, all mixed together.… Those are the common asthma sounds.

 

You know that when you whistle through your lips, you must have them pursed just the right amount in order for the whistle to happen. You can change the pitch of the whistle by changing the airflow and your lips’ positions. But if the lips get too loose or too tight, or the flow through them isn’t just right, there’s no whistle sound made. This same thing is true in the lower airways within the chest. The airflow and diameter in an airway may combine to whistle (wheeze), or they may not. One of the airways may get too narrow to allow a whistle, or the flow may be wrong. The point is that if your child is wheezing, it is only a fraction of the narrowed airways that are making the whistling noises. The rest aren’t whistling, but that doesn’t mean they are all healthy. Many of the other airways also can be, silently, too narrow.

 

Leave a comment

Your email address will not be published. Required fields are marked *