Actually open abdomen today is not “open” but always covered with various non-adherent meshes, with or without applying negative-pressure therapy. The physiology of enteric fistula formation is complex and is related more frequently with “classical” open abdomen, and the evidence from several studies demonstrated that “covered” open abdomen and negative-pressure therapy both reduced significantly the incidence of enteric fistula formation.

I agree with Julianov comment. In fact, since we started using non-adherent meshes in open abdomen treatments, we observed a reduction in the incidence of enteric fistulas. Sometimes they will form anyway in patients who have been in shock for a certain period of time, in these cases tissue hypoperfusion could be considered one of the possible starting points.

All the early experience with vac in "open abdomen" had a higher fistula rate primarily due direct contact of sponge on bowel. However since the introduction of barriers like the vac laparostomy system, placing a non adherent mesh in between the sponge and bowel the fistula rate decreased. There a lot of units that use vac to control fistulas. What used to be a very difficult situation has now become relatively easier to manage. I would however use lower suction when an enterotomy or anastamosis has been made.

If you apply the black sponge directly to exposed bowel you will significantly increase the risk of fistula formation. One should always apply the white sponge first with or without a sheet of mepoteel, followed by the black sponge and the application of the occlusive dressing and suction. Also, the wound must be devoid of purulence as much as possible before applying the vac... The Abthera device is commonly used for the uncloseable abdomen as a temporizing measure.... Again, DO NOT place black sponge on exposed bowel serosa or you almost always will develop a fistula....

Hypoperfusion is the most critical factor for intestinal fistula formation, as pointed out by Dr Dionigi. Obviously, direct contact between the intestinal serosa and a foreign incompatible body like the vac sponge will eventually cause erosion into the intestinal lumen. Using the KCL VAC system correctly, i.e. covered thin sponge on top of the bowel and on top of this the sponge, will certainly protect from fistula formation.

Do not forget however the nutritional factor in such patients, whose needs are excessively increased!

The UK National Institute for Clinical Excellence (NICE as was) has just completed an audit of VAC therapy and fistula risk in ICU patients following the paper from Gordon Carlsson's unit published a couple of years ago

Ann Surg. 2008 Mar;247(3):440-4. doi: 10.1097/SLA.0b013e3181612c99.

Outcome of reconstructive surgery for intestinal fistula in the open abdomen.

Connolly PT, Teubner A, Lees NP, Anderson ID, Scott NA, Carlson GL.

SourceIntestinal Failure Unit, Department of Surgery, Salford Royal NHS Foundation Trust, Salford, United Kingdom.

I think the surgical material like suturing material, mesh etc, may play a role in developing fistula if a local tissue reaction takes place.

As mentioned by some colleagues above, VAC dressings today are safe and can limit development of fistulas, if applicated correctly (sponge not in direct contact with bowel, etc.).

Additionally many independent factors add to the probability of fistula development, as infections, limited immune response, suture materials, chronic inflammatory bowel diseases, malnutrition, etc.

I completely agree with Kai Nowak. These independent factors mentioned are "supporters" of the developement of fistulas; the causative reason for the developement of fistulas however, are external or iatrogenic factors (earlier anastomosis, damage to the bowel, thermal or mechanical lesions to the serosa, ischemia, hypoxia, etc.)

Suction devices of any kind should NOT be used in the free abdominal cavity at all, with the only exception for an anastomotic leakage or other non-formed fistulas deriving from the small intestine, pancreas, biliary, and urinary system, etc. On the other hand, there is no free space left at that time. Suction may be effective for the endoluminal use aiming to reduce the inner pressure so that to diminish the anastomotic suture tension also, as some colleagues prefer (I do not think that way would give any profit, though, just one more myth).

However, I did not see any VAC-associated intestinal fistula if it been placed properly, without contact with the intestinal loops. Dr.Dionigi's opinion seems to be the most probable explanation for intestinal fistulas' cause, but even this remains umcomplete.

The hypoperfusion is a general event, but any given fistula has always a limited pattern, like the perforated ulcer. To the best of my knowledge, nobody has not investigated still what is going on INSIDE the intestine in these cases. Perhaps, there are ischemic ulcers developing there, or something else, still unknown...

Dear Dr. Borodach, I guess you are not involved in the management of patients requiring damage control surgery or open abdomen management. Or I am wrong?

I understood now that the author of this topic meant! The peritoneal cavity produces a good deal 60 Liters of the serum every 24 hours! The open abdomen should oozing like a shower, so that a strategy like this seems to be (and really is!) too aggressive, and fistulas are quite possible to develope (what does not mean that they will develope indeed in every case).

Dr.Julianov, you are right. At an university hospital where I have honour to work in, at any rate, we use these protocols very rare (1-2 cases for several years), in critically ill patients with critically instable hemodynamics, and not more than for 1-2 days, or even less.

fistulas occur when high pressure suction devices are placed nearer to the bowel.Hence most of us keep low pressure.AS mentioned by Dr Gerwin Bernhardt several independent factors contribute for the developement like sepsis and ischemia .Difficult problem in the management in those who require relook laparotomies.Ideally drains should be removed as soon as the condition permits.

We have just VAC for many years, on pediatric and adult livertransplants - with and without existing fistulas with excellent outcome. We have also used VAC in multivisceral transplants with open abdomen without causing fistulas.

It is very clear that with a Damage Control approach and application of a NPWT device, fistulas occur. Even when suction is lowered fistulas occur. Suction is a traumatic force to bowel and it makes sense that fistulas might occur. This is especially true given regular ICU care.

There's an interesting CME program on the topic and VAC therapy in open abdomen I can recommend to everyone on: http://www.naccme.com/program/2012-539-1

to doctor Bonanno

what you mean for Fabien method? I don't know this eponymic

Further to my previous comment, there is data on the suction effectiveness of each of teh devices - KCI and Smith & Nephew, which may have a bearing on the overall rate of fistula formation and the effectiveness of fluid clearance of each type of device based upon suction pressure at the interface. Whether this has an effect on fistula formation rate is as yet unclear in the literature.