Pathogenesis and etiology of the open abdomen

Open abdomen means a non-union of the abdominal wall. Often this results from surgical site infections or wound complications. Infections might be superficial, limited to skin, subcutaneous fatty tissue or muscles. More frequently it originates from the abdominal cavity. A wound dehiscence of superficial layers of the abdominal wall is called incomplete burst abdomen. If all layers are opened the term complete burst abdomen is applied.

A cause for development of an open abdomen might be an inadequate surgical technique. This can be related to kind of suture, chosen material or surgical approach. The most important risk factor is the patient itself with its comorbidities, age, medication and local vascular disorders.

The open abdomen is a severe disease accompanied by high morbidity and mortality. Treatment on the intensive care unit is part of the initial course. The duration of treatment on the ICU ranges from 17 to 65 days. In spite of complex and expensive treatment mortality is as high as 52%. Most common reasons for death are sepsis and multiple organ failure. Overall length of stay in hospital ranges from 45 to 92 days.

Besides various problems of intensive care medicine the open abdomen is accompanied by specific challenges. These are formation of intestinal fistulae, bowel movement disorders, intraabdominal bleeding and infection.

The open abdomen demands combined efforts of patients, nurses and surgeons. The aim of treating an open abdomen must be a closure of the abdominal wall as fast as possible. Unfortunately, this is not always possible. Therefore, a temporary closure of the open abdomen might be necessary. The chosen technique of temporary abdominal closure determines rate of complications as well as rate of final abdominal closure.


Temporary closure of the open abdomen

Open abdomen treatment on the ICU is characterized by respiratory disorders, loss of proteins and fluids, imbalance of electrolytes, considerable limitation of patients mobility, pain, infections and intestinal fistulation. Therefore, temporary closure of the open abdomen is imperative.

The purpose is prevention of complications and reduction of treatment efforts. Furthermore, it should support planned final abdominal closure.

The ideal temporary abdominal closure should meet the following requirements.

- conservation of the abdominal wall

- prevention of lateral retraction of the abdominal fascia

- support of planned final abdominal closure

- possibility of multiple surgical reexplorations while being easily applicable

- short duration of dressing change

- prevention of external re-contamination of the abdominal cavity

- protection against desiccation and damage of viscera

- prevention of herniation and evisceration

- prevention and treatment of abdominal compartment syndrome

- reduction of loss of fluids as well as fluid balancing

- improvement of patient care

- patient compliance and convenience

- prevention of late complications like incisional hernia, intraabdominal adhesions or fistulation

- cost reduction by shortening ICU and hospital length of stay

To date, none of the published procedures, meets all of the mentioned requirements. Otherwise, depending on the chosen technique, considerable differences regarding frequency of complications and rate of final abdominal closure, exist. Vacuum therapy seems to be one of the most effective. This technique is published using different terms like vacuum assisted closure or negative pressure wound therapy or active wound drainage

Etiology of enteroatmospheric fistulae

The formation of intestinal fistulae is a severe complication of treating an open abdomen. Frequency ranges between 4 to 41%, and mortality is increased by 30 to 60%.

The exact reason for occurrence of intestinal fistulae is not always apparently. Often it indicates the severity of the underlying disease. The prognosis depends on various factors. The origin of the fistula can be assigned to small intestine or colon. Size and volume output are also of importance. Spontaneous closure of enteric fistulae can be expected in 30 to 70% of cases. Fistulae open out into an open abdomen are less likely to close spontaneously. The rate is as low as 6 to 37%.

Whenever possible a surgical closure of the fistulae should be attempted. In some cases suturing might be sufficient. In other cases extensive division of adhesions and resection of parts of the small intestine or colon is necessary. Other possibilities are use of adhesives or coagulation activating agents. Unfortunately, sufficient closure of intestinal fistulae is not always achievable.

Longtime treatment of an open abdomen or recurrent attempts of closing enteric fistulae might lead to formation of a frozen abdomen. This means a tight adhesion of intestines with the abdominal wall. Usually this results in extensive wound areas. Fistulae ending in these areas are called enteroatmospheric, in contrast to enterocutaneous fistulae open out into the skin. In most cases, a usual ostomy care is not feasible. Wound care is time consuming and costly. Use of various catheters for drainage often leads to disappointing results.

A new therapeutic option – PPM-Fisteladapter™

Introduction of negative pressure wound therapy has improved open abdomen treatment in many ways. Unfortunately handling of intestinal fistulae remains a serious problem. Suction, applied via sponge to the wound surface, often leads to enlargement of the fistula or eventration of the mucosa. Additionally, viscous stool might obstruct the sponge. This results in separation of sponge and wound surface. The suction becomes insufficient and may lead to contamination or infection of the wound.

Several drain-out systems using negative pressure wound therapy have been published. Unfortunately none of them is reliable. Individual, time-consuming modifications are necessary in most cases.

This led to extensive research in the Department of General, Visceral and Vascular Surgery of the University Hospital Magdeburg. The result was the development of the fistula adapter by Dr. Tautenhahn, Prof. Lippert and Primed Halberstadt Medizintechnik GmbH. By now, there are 4 types of the fistula adapter available, for managing enteroatmospheric fistulae.

The original adapter with a height of 3 cm has an inner diameter of 1.5 cm. The lower brim transfers the negative pressure to the wound preventing dislocation. The upper brim serves for fixation of an ostomy bag. The height of the adapter is adjusted to the usual thickness of the negative pressure wound therapy sponge.

In an initial trial 15 patients were treated using the novel fistula adapter. The device was efficient and feasible. Duration for wound dressing change could be reduced considerably. Patients reported improved comfort. Particularly, stability of the wound dressing and possibility of patient mobilization were beneficial. In this trial problems occurred with two of the patients. This led to development of different modifications of the fistula adapter.

For treatment of deep fistulae a 6 cm high adapter with an inner diameter of 1.5cm is now available. For fixation two super-imposed sponges are used. For management of large sole fistulae or multiple small fistulae being close to each other an adapter of 3 cm height and an inner diameter of 4.5 cm can be used. Due to its flexibility it might be fixed in an oval shape.

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