Sunday, December 10, 2006
Pancreas stuff, #2
Hmm, seems like I've been a bit tardy getting back here. Sorry. Life: the blogger's enemy.
As I recall, I was saying something or other about the pancreas, pointing out its difficult anatomy, tucked back there behind the stomach and the colon (did I mention that the main artery to the spleen, a big one, passes right along the edge of the pancreas?), and suggesting ever so subtly that when aroused it can turn from a fluffy and pink-cheeked organ into a devouring juice-dripping and slobbering monster, the bane of a surgeon's existence, and the most awful of threats to its owner. Or something like that.
It's acute pancreatitis that's the most horrible (not that chronic pancreatitis is particulary serene: it might not kill you like its acute cousin, but under some circumstances it might make you wish it would. More later on that subject.) In a tidy private practice the bulk of the acute pancreatitidies show up as a result of gallstones. In the county hospital, mostly it's alcoholics on a bender. The latter are the worst, in part because they are generally in worse physiologic shape to withstand the assault, and in part because alcoholic pancreatitis just happens to be the baddest actor.
As I explained all too briefly, gallstone pancreatitis occurs when a stone passes out of the gallbladder into the bile duct (I've also been tardy in getting around to a series of posts on gallbladder disease. It'll happen.) If you refer to the diagram in my previous post, you can see that if a stone were to lodge in the south end of that duct, below where the pancreatic duct joins it, bile could, instead of passing into the gut where it belongs, be forced backwards into the pancreatic duct. Experiments have shown that squirting bile into a (mouse's, I think. Maybe a fruit fly's) pancreas causes pancreatitis; so that's the presumed mechanism. If the stone passes finally, the process may be self-limited; in fact, the bulk of patients with gallstone pancreatitis -- sick as they might be, and impressively scary as their lab work can get -- tend to get over it in a few days with only supportive measures, followed by a properly timed operation to get rid of their gallbladder. So ideally, when such a patient is admitted, the surgeon is involved early on, consultatively speaking, and hopefully the patient has the good fortune and the surgeon has the good sense to avoid early intervention, scalpelly speaking. If not, it's a hell of a mess.
Nowadays, as a result of some better-late-than-never studies showing that even with infection, non-operative management may be better than operative, surgical treatment of acute pancreatitis is done less often than when I was learning the game. Back then -- and, unavoidably and miserably, sometimes even in the age of reason -- I got involved in some pretty horrible morasseri. The most memorable was a lady of high social, political, and academic standing in her native Asian country, transferred to us by a surgeon who'd trained years earlier at UCSF, where I was then chief surgical resident. He'd operated on her once in their country and had arranged a special flight to San Franciso. After a long ride, she arrived in bad shape.
It would take a better writer than I to describe the hell-hole created by acute pancreatitis at its worst. It's that combination of highly unfortunate location and the power of self-digestion that turns the upper abdomen into a seething and distorted mess. Imagine a nicely-tended garden overtaken by sewage. Think of trying to find your way through a mine-field, knowing a misstep could cause death, while wearing size twenty shoes, and blindfolded. Compare being required to reach into a shallow pan of water to find by feel a couple of well-defined objects, with groping into hot mush, mittened and scared. See? I takes a better writer than I. None of that does it justice.
In a normal person, maybe one on the slim side. exposing the pancreas is among those surgical moves that I find quite cool: it's one of those little revelations of anatomy, the knowing of which (every surgeon does) feels like having been taught a secret handshake. The transverse colon travels just under the bottom edge of the stomach. (Strangely, the best illustration I could find is from an article containing complete bullshit.) Perfectly placed, a cut into the tissues that bridge those two organs can open into a delicate place, the "lesser sac (lousy diagram, but one that might make you think "Wow, you surgeons really need to know your stuff.") Tucked behind the stomach and colon, that space is clean and quiet, opens sort of magically; and its backside is -- ideally -- that pink and normally-firmer-than-normal organ, the pancreas. There for your viewing pleasure. With acute pancreatitis, not only is that space completely obliterated, it's filled with indistinguishable stinky goo, and the edges of the stomach and colon -- out of which you'd dearly like to stay -- are absolutely undecipherable, unrecognizable, and half-digested. Not good. Which is why, as I mentioned in my previous post, we used to navigate it with a spoon.
Draining pus is one of the most time-honored things a surgeon does. Open an abscess, liberating a well-defined collection of stomach-turningly stinking cream, and without question you've done a body good. Pancreatic infection is nearly never like that: it's a quart milk-carton-sized uncircumscribed (read that word carefully) zone of corruption, at the periphery of which you know is extreme danger if breached, but the outlines of which are indefinable. Your goal is to rid the area of all the infected tissue and to provide multiple avenues of egress for retained and future collections. That spoon helps: you figure if you can scrape it out with a some-what delicate sweep, it wasn't meant to be there any more. It's blunt enough that you might avoid stumbling into the colon or stomach, or important vessels. The corruption thusly removed contains the occasionally recognizable chunk of pancreas, globs of saponified fat, and lots of crud. Almost by definition, you can't do a thorough job; nearly always is it necessary to go back and do it again, once you've decided to take the surgical approach. Again; and often again and again. In fact the need to do so has led to a few inventive methods to facilitate reoperation; including an actual zipper, applications of plastic place-holders, and tacking the edges of the abdominal wall down into the hole, exposing the target area, and holding the rest of the abdominal cavity out of the way (that's called marsupializaion, descriptively enough.)
We just closed our Asian lady loosely each time with monster sutures. We left huge drains in the field, tubes that allowed irrigation of anti-biotic solution in and out. During one of the operations it was apparent the infective-digestive process (remember the digestive enzymes of the pancreas have been released and are eating away at the fats and proteins in the area, making the process an ongoing and self-perpetuating one) was working its way into the blood supply of the colon, and that the transverse colon was compromised. A portion got removed (not easily, given the absent landmarks), accompanied by colostomy, which added an ongoing source of contamination to the soup. In between operations, her splenic artery blew, requiring a hand into the wound in the ICU, followed rapidly by a trip back to the OR. She nearly died a few times, from sepsis, from organ failure, from that bleeding episode. But somehow she made it. Somewhere I have a beautiful hand-embroidered silk tablecloth she sent me when she returned home. Not everyone I saw with that disease made it. Not everyone who made it -- the county hospital alcoholics -- expressed gratitude.
Surgeons, when forced into it, can change; can recognize or even promote progress. The radiologists -- damn 'em and bless 'em -- have produced all sorts of techniques to bail out surgeons, as well as to supplant them. When a defined abscess occurs in a pancreas, they can guide a wire followed by a drainage tube into the area; it's enough to turn the tide without operation in many cases. Some things those guys do have robbed me of surgical fun (pancreatic pseudocyst is one example -- next post): taking away the need to operate on infected pancreii is a job happily ceded. Bolstered by the evidence of recent studies, and by the up-sleeved tricks of the radiologist, I've successfully observed the resolution of acute pancreatitis in several patients on whom I might have operated years ago. Most excellent. Next post, I'll talk about the pancreatitis-related operations I actually like to do...