Mucus: It's a love/hate relationship

By George Barnes MS CCC-SLP

Ever wonder about mucus? Ponder deeply about it? No? Just me? Well then, I hope I can get you a little bit more excited about this absolutely wonderful secretion. Let’s take a deep dive into mucus (that didn't come out right) and see how understanding it can improve care.

We don’t like talking about mucus. It’s thick, sticky, turns rainbow colors, and tends to pour out of our nose at inopportune times. We only think about it when we have to. Like when we’re sick and it’s suffocating us or when we are out on a first date and we’ve, for some reason, chosen the spicy Thai basil chicken as our entree (true story). But mucus is everywhere, not just in our noses and throats. Not only does it line the entire respiratory system starting from the mouth all the way to the alveoli, but it also lines our digestive system and helps with many other bodily functions (Zheng & Clements, 2018).

For the sake of dysphagia management let’s talk about the benefits it has for the aero-digestive system. It serves a few main purposes: as a sticky substance to catch foreign materials, a selective barrier to protect our inner cells, a lubricant for the airway’s cilia, and to secrete immune defenses (i.e. white blood cells) to fight off germs (Lai et al., 2009; Lieleg & Ribbeck, 2012; Zheng & Clements, 2018). Next time you blow your nose, you’ll have whole newfound respect for your little mucus friend. Or maybe not…

Friend or Foe

Mucus is 90-99% water so expectantly its viscosity is relatively loose (Lieleg & Ribbeck, 2012). This viscosity, along with the volume and color, changes with illness. Everybody has witnessed this. You have a cold and you’re up all night because your airways are clogged and you can’t cough it out. Don’t blame the mucus, it’s only trying to do its job. It’s just trying a bit too hard. Mucus becomes thicker, more voluminous, and changes color when there’s a problem. With infection, for example, it becomes filled with all sorts of stuff (e.g. white blood cells, immune defense chemicals, germs, etc.) (CDC, 2006). With allergies, mucus over-responds to the foreign material you are allergic to which results in hypersecretion of mucus; making the response worse than the cause (Kind of like the people who beep in traffic) (Monroe et al., 1997).

On top of hypersecretion, airway cilia can also be damaged. With infection, people who smoke, and chronic respiratory disease (e.g. COPD, cystic fibrosis, etc.), the sweeping motion of cilia becomes immobilized which results in the mucus (and other unwanted contents) sticking around instead of going upward and outward (Mall, 2008; Shen et al., 2018; Smith et al., 2014). There is then not only MORE of the mucus but it becomes thicker and even more difficult to clear.

Even without illness, such as in a cold dry environment, we may have an over-production because the body is constantly trying to compensate for the lack of moisture in the air (NPR, 2011). This is also why we see an overproduction of mucus after tracheostomy: The trach tube bypasses the mouth and nose which are meant to filter, humidify, and warm the air before it gets to the lungs (Johns Hopkins, ND). Dehydration is also a problem for your mucus (remember the mostly water thing): With less fluid in the mucus, it becomes thicker and less manageable (Lai et al., 2009).

Why we care about mucus:

Excess mucus is not just annoying, it can be deadly. It can obstruct the airways causing a decline in respiratory function or suffocation (Shen et al., 2018). Further, thick and copious mucus disrupts the body's ability to clear and filter out germs, leaving the lungs more susceptible to infection. This can snowball into a vicious cycle of more inflammation, more secretions, and further respiratory decline (Shen et al., 2018). 

What we can do:

Many opt for scopolamine and antihistamines which reduce the mucus, but often at the expense of making it thicker and even harder to clear. A better approach is to utilize medications that open the airways (i.e. bronchodilators), reduce inflammation (i.e. steroids), and/or loosen the secretions (i.e. mucolytics or expectorants) (Shen et al., 2018). This way we aren't fighting the mucus itself, but rather allowing the body a better chance to clear it on its own (Kind of like avoiding the traffic (and the pointless beeping) by taking a new way to work).

My plight with mucus:

Mucus is good. But it IS possible to have too much of a good thing. Mucus might be annoying for most of us, but with our vulnerable patients, it can be life-changing. This is why it is our duty to advocate for proper mucus management. Next week, I continue to meditate about mucus, but this time I address its very close cousin, saliva, and how it can directly impact our patients with dysphagia. See you there!

Comment below. I love to hear your thoughts!

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