Sunday, June 22, 2008

A Mastedon Makes an Obstruction

I'm beginning to think the Italian sausage theory of my obstruction isn't so crazy after all.  In this post, I'm going to copy a description of how our guts are designed to deal with digesting big hunks of meat we come upon serendipitously, whether by stumbling on a big kill or browsing the lunch counter at Lina's.  

It might fall into the TMI category of more detail than you want about how the gut works, so feel free to ignore it, especially if you are a friend who has to listen to mine sloshing and growling these days.  But if you want to know more about why cancer interferes with normal bowel functioning, this is as good a description as anything I've found.  It's in a book by James Hallenbeck called Palliative Care Perspectives

    The intestinal tract did not evolve to compensate for mechanical bowel obstruction caused by an immobile, fixed lesion such as cancer. The physiologic changes that arise with obstruction would be adaptive to reversible forms of bowel obstruction that may have occurred for our ancient ancestors, but they are maladaptive for patients with cancer. Similarly, kidneys demonstrate a maladaptive response to heart failure. Decreased renal perfusion is sensed as dehydration. Fluid is retained to compensate when, in fact, the patient is drowning. We adjust for this by "overruling" the kidneys, telling them to get rid of salt and water and not hold on to them. The kidneys can be mistaken. What "misunderstanding" arises in bowel obstruction?

    Imagine that you have been very hungry. Your tribe finally hunts down a mastodon, and it is time for a feast. You gorge yourself, eating great chunks of meat and causing a temporary obstruction. Your body would respond in the following way.

    1.  Mechanoreceptors and chemoreceptors would be stimulated by the distention caused by the large build-up of food proximal to the blockage. These receptors would tell your brain to stop eating. 
    2.  The intestine proximal to the blockage would begin hypersecreting fluid, trying to flood the system and wash the intestinal contents downstream.
    3. Intestinal motility would increase, further trying to push contents downstream and causing cramping.
    With luck, you would live to hunt another day. While this approach works well for ingested mastodons, it works poorly for malignant bowel obstruction.

In essence, what Hallenback is describing is what made me call my doctor. I was nauseous (stop eating, Pat, and get rid of what you just put in your stomach because it ain't going anywhere). My gut was scramping. Oddly, the best description of the pain for something so serious is that it was colicky. I could hear fluid roaring and sloshing around, trying desperately to wash stuff downstream.

There just wasn't anywhere for it to go.  The blockage formed a little dam, and everything nature was telling it to do, except for not putting in more mastedon, was starting to work against me.

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