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|Newsletters: Decision Making in Surgery|
Decision Making in Surgery
David Kuehler, MD, is an assistant professor in the department of surgery at Albany Medical Center; he is a general surgeon with a concentration in abdominal surgery. He spoke to a gathering of homePEN consumers and clinicians at the Oley Region II Spaghetti Dinner, held September 21, 1996.
Dr. Kuehler began his talk outlining one of the major factors affecting decision making during abdominal surgery: how much length and function are left of the patient’s digestive system. This includes disorders affecting the esophagus, stomach, pyloric valve, duodenum, jejunum, ileum, ileocecal valve and the large intestine. The shorter the length of bowel, and the absence of critical portions such as the ileocecal valve, the lower the bowel’s capacity for absorption. Normal adults have approximately 30 cm of duodenum, 300 cm of jejunum and 200 cm of ileum, and need at least 60 cm of jejunum or ileum to be able to maintain themselves on an oral diet. When the ileocecal valve is present, the length of small intestine needed to maintain an adult on an oral diet can be shorter (30 cm). In infants the amount is somewhat less, 40 cm and 15 cm respectively.
When considering bowel length, it is important to note that an infant with short bowel syndrome who is dependent on hyperalimentation at first, may be able to maintain themselves on an oral diet later as their gut grows with the rest of their body and adapts to meet their changing nutritional needs. He added that adults may also experience gut adaptation after surgery and that new regimes such as growth hormone and glutamine are being investigated to determine whether they promote this adaptation.
In an effort to increase absorption in the patient with short bowel syndrome, surgeons in some medical centers have tried fashioning an ileocecal valve out of a piece of the existing gut when the original valve has been removed. However, this procedure is not done routinely because of the risk of blockage or intestinal compromise. Also with Crohn’s patients surgeons prefer to limit bowel surgery as much as possible since the disease usually recurs.
Surgeons have also tried repositioning a portion of a shortened bowel backwards such that the peristalsis (movement of the intestine) works in reverse to slow down the digestive process, but this can also lead to many complications, warned Dr. Kuehler; the worst of which is the tendency for blockage and the need for surgical removal with loss of more bowel.
Another procedure the medical community has some success with is bowel lengthening. This is achieved by splitting the small bowel in half lengthwise and stitching it back together, end to end. This lengthens the bowel, but has the risk of loss of the bowel if the blood supply is compromised.
A question was asked if vagotomy, where the vagus nerves are cut, would help. Vagotomy lowers the amount of stomach acid and may decrease the stomach fluid produced, but has other side effects, including poor functioning of the stomach and sometimes diarrhea. Therefore, vagotomy is not used for short bowel (though it may be used for ulcer disease).
Dr. Kuehler mentioned that scar tissue or adhesions are another major consideration when contemplating bowel surgery. Unfortunately, scar tissue often develops on and around the bowel as a result of intestinal surgery. Sometimes these adhesions cause few or no problems. However, in other cases the adherence of one section of small intestine to another section restricts the normal motility of the bowel and eventually may cause the bowel to kink or twist and to develop an obstruction. In addition, when present in large amounts or in an inopportune place, scar tissue can mask the bowel, making a second surgery on the bowel extremely difficult. As Dr. Kuehler put it, “Getting through the scar tissue to operate on the bowel can be like chipping through a cement block to get at a china cup.”
Determining Which Portions to Cut
Another surgical decision involves determining which section of the bowel to remove. This, of course, will depend upon the underlying disease process. Short bowel syndrome may result from ischemia or loss of blood supply to the bowel. “Blood supply may be lost for a number of different reasons, including a hernia or birth defect,” said Dr. Kuehler. When operating to correct this problem, it may be difficult to determine which section of the bowel is still alive and which section is non-viable. “It’s easiest to recognize non-viable bowel when the section has been dead long enough to develop gangrene,” explained Dr. Kuehler. When it is not so obvious, the surgeon may stimulate the questionable section to observe peristalsis. Another possibility is to introduce a fluorescent dye into the patient’s bloodstream. By observing where the dye travels, the surgeon may see which sections of the bowel are still receiving an adequate blood supply. However it is still difficult to be sure, and in most cases, a doubtful section of bowel is left in and a second operation is planned in one or two days to recheck its viability.
When Crohn’s disease is the reason for surgery, the experience of the medical community has shown it is best to remove as little of the affected bowel as possible, noted Dr. Kuehler. Because of this a surgeon will typically remove only those parts of the bowel which are most affected by the disease, leaving behind sections that are mildly diseased. These mildly affected areas may never get worse, and by keeping them, the patient may be able to retain more functioning bowel in the long run.
When the reason for surgery is a stricture in the bowel, the decision to remove the narrowed section may be mitigated by the possibility of widening the area using a procedure called stricturoplasty. This entails making a longitudinal (lengthwise) incision in the stricture and stitching it up transversely (widthwise).
“As a general rule, when the length of the patient’s bowel is already compromised (by short bowel syndrome) surgeons will make more of an effort to retain as much of the remaining bowel as possible,” said Kuehler. In other words, the disadvantages of shortening an already short bowel weighs heavier on the decision than other factors such as the risk of leaving in a portion of the bowel that is slightly compromised. On the other hand, when the length of bowel is less critical, the surgeon may make a more generous cut to ensure that both ends of the bowel to be reconnected are fully healthy. This ensures a better connection, lowers the risk of infection and lessens the risk of future surgery.
In other situations the surgeon has less control over the length of bowel to be removed. For example, the surgeon may have to take a large portion of the intestine, some of which is still healthy, because the blood supply for the entire section will be cut off when the unhealthy portion of the bowel is removed. This is particularly the case with the large intestine since blood is supplied to this organ in relatively few areas.
Another factor to weigh when making a surgical decision, is whether to bypass an affected area of the bowel or resect it. Surgeons usually prefer a resection because of the potential for the bypassed section to result in a “closed loop” where there is stagnation and inadequate drainage of bowel contents. This situation creates the potential for bacterial overgrowth which produces gas and cramping, and interferes with absorption which leads to diarrhea. It may also be a source for infection. However, there are cases where a bypass is a better risk than a resection. Such is the case when there is a build up of scar tissue and the risk of cutting into the good portion of the bowel is too great. “It’s all a matter of balancing the risks with the benefits,” he said.
During the question and answer period, a patient inquired about having his gall bladder removed during another surgery he needed in his abdominal cavity. Gall stones were present, though not giving him trouble yet. Dr. Kuehler responded, “When operating on a patient with short bowel syndrome where the likelihood of gall stones is increased, you need to balance the risk of adhesions from extended surgery against the benefits of avoiding a future surgery.” Sometimes, like in the case of appendicitis, there is no choice. You must remove the appendix. However, with gall stones, it’s not such a cut and dry decision. “Basically, it’s the same process of balancing the risks when making an intestinal surgical decision - just the stakes are higher” he concluded.
Another point Dr. Kuehler made was to not be afraid to ask your surgeon questions and to make suggestions. This issue was raised when a member of the audience asked about having an Enterostomal Therapy (ET) nurse chose the site for an ostomy. Dr. Kuehler noted that in the case of emergency surgery, this is probably not an option. But when undergoing scheduled surgery which may result in an ostomy, the patient would be wise to ask if an ET nurse might assist the surgeon in choosing the ostomy site. “The ET nurse will be able to work with the patient to identify a site that is less likely to cause trouble in the future and is easier to care for,” he explained.
Finally, in response to another question, Dr. Kuehler told the audience that once a patient has undergone bowel surgery, there is no time limit as to when adhesions may cause a problem. Adhesions and scar tissue form rather quickly (within the first few weeks) and tend to soften over time, lending more flexibility. “So if there’s going to be a problem, it often occurs soon after the surgery; however, the possibility still exists for that adhesion to cause a blockage at any time down the road,” said Dr. Kuehler. On a brighter note, he mentioned that only two to three percent of surgeries develop adhesions that cause a blockage bad enough to require further surgery.
Copyright © 1995 The Oley Foundation