Saturday, January 10, 2009

CF through pictures

On Thursday morning, we had presentations by the Cystic Fibrosis (CF) team at St. Michael's Hospital in Toronto. Since we weren't going to be rigorously tested on the material, I took the opportunity to doodle, as I often do. It keeps me awake and leaves me sufficiently attentive to take in a reasonable amount of information - just not every gritty detail (which is what I would need for an exam).

Because I still care about my education, and because I didn't want to waste my entire morning, I was still trying to absorb what was being said. The result was a bunch of doodles about CF. I thought I would share a bit of this newly acquired knowledge with you through pictures.

Dr. Elizabeth Tullis heads up the CF team at St. Mike's. Cystic fibrosis is characterized by thickened mucus everywhere in the body, but particularly in the lungs. This clogs up the lungs, making it difficult to breathe - thus decreasing lung function and the FEV1, or the rate at which you can breathe out in one second. It also leads to recurrent infections because it's difficult to clear bacteria out of the lungs. The bacteria are trapped in the mucus, and the mucus is so thick that it is hard to expel it.

The thickened mucus is caused by a defect in the CFTR channel of cells. This channel transports the chloride ion (Cl-) across the cell membrane. Usually, the cells in your lungs have a layer of hair-like projections called cilia. The cilia are suspended in a liquid (or sol phase) with their tips in the mucus (or gel phase). The mucus traps foreign particles and bacteria in your lungs, and the cilia beat in a wavelike motion to push the mucus out of your lungs and into your gastrointestinal tract.

In cystic fibrosis, the CFTR channel is broken, and so ion transport is impaired. Normally, there are channels that allow sodium (Na+) into the cell. The CFTR channel pushes chloride out of the cell, and sodium follows. Without the CFTR channel, sodium is drawn into the cells but does not go back out. As sodium is drawn in, water follows by osmosis. The lungs dry out, and the liquid phase is lost. The dry mucus is much thicker and pushes down on the cilia. Thus the cilia cannot beat, and the mucus cannot move. This makes it easy for your lungs to get infected.

One way to get the mucus out of the person is called the ketchup manoeuvre. Essentially, you turn a person on their front and pound their back like getting ketchup out of a bottle. This helps to forcefully move push the mucus out of the body without the help of cilia. As you can see, my English abilities failed me and I couldn't figure out how to correctly spell manoeuvre.

There are five types of mutations that can lead to cystic fibrosis. The CFTR channel may not be made at all (I - synthesis), the channel protein may be made but be malformed (II - maturation), the channel protein may be formed but is unable to be turned on (III - activation), the channel may be turned on but lets ions through too slowly (IV - function), or the channel may be completely normal but there are too few of them (V - abundance). Type IV and V mutations are the least severe.

Cystic fibrosis also affects other body systems. For instance, the pancreas (in red) forms fibrotic cysts (after which the disease is named). Normally, the pancreas forms enzymes that are essential for digestion. Without a normal pancreas, fat is not taken up normally. In order to improve the condition of patients, Toronto hospitals spearheaded an initiative to compensate via dietary supplementation of food and pancreatic enzymes (in pill form). As a result, survival of Toronto CF patients proved to be significantly better than similar centres worldwide.

CF affects many more systems than just the lungs and the digestive system, however. For instance, many men with cystic fibrosis suffer from infertility. That's because they often don't have a functioning vas deferens. The vas deferens is the tube that carries sperm from the testicles to the penis. So while they can make sperm, none of those sperm will ever make it to the outside world.

Living with cystic fibrosis is challenging. Activities are limited by the condition, and many hours a day are spent doing exercises and taking medications to manage symptoms. Dr. Tullis described one patient who came to Toronto every week from Terrace Bay, Ontario for treatment without ever complaining. It was only after many years that she actually asked where Terrace Bay was. It's far.

In conclusion, cystic fibrosis is a disease that affects many different body systems. As such, it requires multidisciplinary care from a wide range of specialities including respiratory (I tried to draw some lungs there...), gastrointestinal (a stomach), endocrine (a pituitary gland, which produces hormones), and obstetrics (a fetus).

Hope that was interesting!

1 comment:

Alexis said...

I didn't expect to see an entry today at all. So nice of you to write so diligently. =) By the way, your background music kind of makes me sad. =/