When surgical dogma is challenged

From my perspective, one thing that's always been true of surgery that has bothered me is that it is prone to dogma. I alluded to this a bit earlier this week, but, although things have definitely changed in the 20 years since I first set foot, nervously and tentatively, on the wards of the Cleveland VA Medical Center for my first ever surgical rotation, some habits of surgeons die hard.

Of course, regardless of the tendency towards dogma, one thing that differentiates evidence- and science-based medicine from pseudoscientific woo is that studies do make a difference. In general and oncological surgery, nowhere is this truth more obvious than in how we take care of patients after major abdominal surgery. When I started as an intern, the dogma was that all patients with major abdominal surgery, particularly if an anastomosis was done (an anastomosis is the sewing or stapling together of two cut ends of bowel to reconstitute its lumen) had to remain NPO (nothing by mouth) until they passed flatus and, indeed, that they should all have nasogastric (NG) tubes to drain the stomach and decompress the bowels until they pass flatus. The rationale behind this practice was that trauma to the bowel led to what is known as an ileus, which is where the normal peristaltic motion of the bowel shuts down for a while, sometimes leading to vomiting. Consequently, it was believed that after major abdominal surgery decompression of the bowel by sucking out the bowel contents with a tube would prevent too much bowel distention, forestall vomiting, and thus prevent aspiration. This virtually universal practice of keeping an NG tube in until the patient passed flatus and slowly advancing the diet after that from liquids to soft diets to a regular diet led to my frequent joking as an intern to patients about how surgeons are obsessed with farts, because we would ask patients on rounds twice a day whether they had passed gas yet. Personally, with some patients I would ask if they had farted yet, and this seemed to amuse the ones whom I thought it would.

Over the next decade or so, this particular bit of surgical dogma has been increasingly questioned. No doubt this was in part due to the increasing infiltration of laparosocopic techniques into surgical practice, the main benefit of which was (and is) less pain, faster time to regaining of bowel function. Increasingly, well-designed studies suggested that NG tubes were not necessary for surgery in which the bowel was not cut, for major gynecologic surgery, and for most colon surgery. Indeed, nowhere has routine surgical practice changed more in response to data than in how we use NG tubes. When I was an intern, a patient who underwent a colon resection could expect to have an NG tube in several days and not to be able to eat until after that. These days, most surgeons take the NG tube out in the recovery room and let the patient have liquids the next day. I'm by no means saying this happened overnight, but it did happen over about a decade even in a conservative specialty like surgery. Data triumphed over dogma.

If a paper in last month's Annals of Surgery¹ is any indication, it looks as though another surgical dogma may be teetering and ready to fall.

The dogma that I'm referring to is the remaining practice of using NG tubes in anyone with upper gastrointestinal surgery (liver, stomach, pancreas, duodenum, proximal small intestine) and then placing a jejunostomy tube (a tube, also often called a J-tube, that goes into the jejunum, or the proximal part of the small intestine, through which feedings can be given). The rationale for this was that the peristalsis of the small bowel returns almost immediately; it's the large bowel and stomach whose return of peristalsis is delayed. Consequently, liquid tube feedings, it was thought, could be given beyond the point of surgery into the small bowel because if there is one surgical dogma that the evidence generally supports and probably always will, it's always better to use the gut for nutrition than to use total parenteral nutrition (TPN, or feeding by veins). Moreover, there was evidence that such feedings had a protective effect on the lining of the bowel, preventing a phenomenon known as bacterial translocation, in which bacteria could pass through the compromised lining of the bowel after surgical stress. The price, however, was the placement of a tube into the proximal intestine, a procedure that, while safe, was definitely not without complications, some of which (such as bowel perforation) could be serious and require reoperation.

Challenging this dogma is the largest multicenter randomized study yet looking at this question: Which is better, bowel rest (NPO) and J-tube feedings or just letting the patient eat the next day? The study comes out of Norway¹ and involved 453 patients. Blinding, much less double blinding, was, as is the case in many surgical trials, not possible because of the very nature of the question being examined, but other than that the design of the study was about as strong as a surgeon could ask for. Basically, patients were randomized to a routine of NPO and J-tube feeding until flatus indicated return of bowel function versus normal food at will beginning on postoperative day one; the experimental design is summarized below:

The patient mix was pretty well controlled for, with similar patient mixes in each group. The results were striking. In the enteral feeding (ETF) group, 33.5% had major complications compared with 28.2% of the patients allowed normal food at will, a difference that was not statistically significant. In the ETF group, 15.2% of patients required reoperation while 13.2% in the normal food at will group did, again a difference that was not statistically significant. There was similarly no difference in mortality. Moreover, time to resumed bowel function was actually shorter in the normal food group. Specifically, time to first flatus was 3.0 days in the ETF group and 2.6 days in the normal food group, which was statistically significant. Of course, whether a less than half a day difference is clinically distinguishable is debatable, but at the very worst there was no difference between the groups, and NG tube reinsertion was only required for vomiting in the regular food group about 20% of the time.. Certainly, there was no different between time to first bowel movement, and hospital stay was actually slightly longer in the ETF group (16.7 days versus 13.5 days, p=0.046). Worse, there was a definite complication rate from the J-tube insertion, with 2/224 patients in the ETF group requiring reoperation to deal with such complications.

One of the interesting things about this study was that it was a heterogeneous group. Indeed, it was not, as most such studies, limited to elective surgery but rather included emergency surgeries, including ones that involved gross contamination of the peritoneal cavity with gastrointestinal contents. The subgroup analysis that could be done failed to find a difference between the two groups even for these sorts of emergency operations. On the other hand, the very heterogeneity of the two groups, with multiple different operations, including pancreatic, liver, spleen, and stomach operations, leaves open the possibility that the results may not apply for every upper abdominal operation. Specifically, there were few esophageal operations in the mix because surgeons were reluctant to sign up patients undergoing esophageal operations for the trial. Indeed, for esophagectomy, the general standard of care right now is to wait at least two or three days and then obtain a swallow study in which the patient swallows radioopaque contrast and is filmed on fluoroscopy to make sure there are no leaks at the anastomosis. If there is no leak, the patient is allowed to have liquids and then to eat. Personally, I can't blame them. If I still did esophageal surgery, I'd be reluctant to allow my patients to eat normal food on postoperative day one as well. However, given the results of this study, if I still did esophageal surgery, I'd be much more receptive to letting my patients sign up for a followup trial to look specifically at whether it's safe and efficacious to let patients undergoing esophageal surgery eat so soon after their operations. I would hope that esophageal surgeons would now feel the same.

Another aspect of this study that is of interest is the whole question of whether feeding a postoperative patient makes a difference. Unfortunately, it can't clearly answer the question of whether providing "optimal" calories by an enteral route leads to a better outcome, a question that has been debated for many years, with a number of studies suggesting that enteral feedings are associated with a more rapid return of bowel function and fewer complications. The reason is that the authors did not record the actual food intake of either group. As the accompanying editorial observes, "Unfortunately, the authors did not actually measure food intake in patients in either group to determine if allowing food actually resulted in patients taking in food during the first five postoperative days." Still, this study is quite important because it's the largest of its kind and it's about as well-designed as such a study can be.

The longstanding surgical dogma that NG tubes are necessary after abdominal surgery an that it's dangerous to feed patients until flatus has returned has been under a sustained assault by a number of large studies over the last decade or so. The last holdout of this dogma has been the case of upper GI surgery, where it was still believed that bowel rest, often with NG tube decompression. The first to fall was the use of NG tubes after non-GI operations, such as gynecological procedures, followed by most colon operations. This study strongly suggests that neither bowel rest, NG decompression, nor the witholding of food is necessary after upper GI surgery as well, with the possible exception of esophageal surgery. Another surgical dogma appears to be on the verge of biting the dust in the face of evidence from well-designed clinical trials. Moreover, if this trial is correct, if anything, it suggests that immediate feeding is actually better than the old way.

You might think that this would disturb me. It doesn't. What it does is to demonstrate in a very striking way the very best of science-based medicine: The ability and willingness to change practice based on new evidence. I won't kid you by claiming that such shifts in dogma ever come easy. It will likely be several years before enough replications of this study convince upper GI surgeons that not feeding their patients the next day after major abdominal surgery is at least as safe as the old way. Dogma may not change in the face of evidence as fast as we would like, but on the other hand if it would also be undesirable if dogma changed too easily. Contrast this to so-called "alternative" medicine, where, no matter how much evidence shows its nostrums to be no better than a placebo, its practitioners hold on to them all the tighter. Surgeons and other evidence-based practitioners may be sometimes too slow to give up their dogmas, but eventually they will heed the call of the evidence.

REFERENCE:

1. Lassen, K., Kjoeve, J., Fetveit, T., Trana, G., Kjartan, H., Horn, A., Revhaug, A. (2008). Allowing Normal Food at Will After Major Upper Gastrointestinal Surgery Does Not Increase Morbidity: A Randomized Multicenter Trial. Annals of Surgery, 247(5), 721-729.