Multicentre prospective study of fascial closure rate after open abdomen with vacuum and mesh-mediated fascial traction

Abstract

Background

Damage control surgery and temporary open abdomen (OA) have been adopted widely, in both trauma and non-trauma situations. Several techniques for temporary abdominal closure have been developed. The main objective of this study was to evaluate the fascial closure rate in patients after vacuum-assisted wound closure and mesh-mediated fascial traction (VAWCM) for long-term OA treatment, and to describe complications.

Methods

This prospective study included all patients who received VAWCM treatment between 2006 and 2009 at four hospitals. Patients with anticipated OA treatment for fewer than 5 days and those with non-midline incisions were excluded.

Results

Among 151 patients treated with an OA, 111 received VAWCM treatment. Median age was 68 years. Median OA treatment time was 14 days. Main disease aetiologies were vascular (45 patients), visceral surgical disease (57) and trauma (9). The fascial closure rate was 76·6 per cent in intention-to-treat analysis and 89 per cent in per-protocol analysis. Eight patients developed an intestinal fistula, of whom seven had intestinal ischaemia. Intestinal fistula was an independent factor associated with failure of fascial closure (odds ratio (OR) 8·55, 95 per cent confidence interval 1·47 to 49·72; P = 0·017). The in-hospital mortality rate was 29·7 per cent. Age (OR 1·21, 1·02 to 1·43; P = 0·027) and failure of fascial closure (OR 44·50, 1·13 to 1748·52; P = 0·043) were independently associated with in-hospital mortality.

Conclusion

The VAWCM method provided a high fascial closure rate after long-term treatment of OA. Technique-related complications were few. No patient was left with a large planned ventral hernia.

Introduction

The concepts of damage control surgery¹ and temporary open abdomen (OA), with emphasis on reversing physiological exhaustion, in numerous acute conditions and critically ill patients have been widely adopted, both in trauma² and in non-trauma³ situations. Consequently, management of the OA has become an important clinical issue. Early fascial closure of the OA seems feasible within a week in the majority of younger trauma victims⁴, whereas a longer time may be required in elderly patients undergoing OA treatment owing to abdominal infection or after operation for ruptured abdominal aortic aneurysm (AAA). Irrespective of the technique used, abdominal closure should be performed as soon as possible without compromising the patient's physiological condition. The frequency of large ventral hernia as a result of OA treatment should be minimized.

The combination of vacuum-assisted wound closure (VAWC)⁴ and mesh-mediated fascial traction (VAWCM) has been shown to be effective in approximating the fascial edges in patients treated with long-term OA in a preliminary study⁵. A major concern with all techniques used for temporary abdominal closure has been the reported occurrence of enteroatmospheric fistula⁶. The main aim of the present multicentre prospective study was to investigate the primary delayed fascial closure rate in patients treated by the VAWCM method, and to describe technique-related complications. A secondary aim was to study factors associated with failure of fascial closure.

Methods

This multicentre prospective study was approved by the ethics committee of Lund University and was registered at http://www.clinicaltrials.gov (registration number: NCT00494793).

Consecutive patients treated for an OA in four study centres in Sweden (Malmö, Uppsala, Falun and Gävle) were included in the study between 1 April 2006 and 31 August 2009. Exclusion criteria were age less than 18 years, abdominal wall hernia before OA treatment, anticipated OA treatment lasting fewer than 5 days and non-midline incisions. Analysis was performed on an intention-to-treat and per-protocol basis. All patients with intestinal necrosis and perforation, bowel anastomotic leakage, traumatic iatrogenic or non-iatrogenic injuries to the enteric or urinary system, or enteroatmospheric fistula were reassessed individually by the study investigators, and possible intestinal fistulas secondary to VAWCM treatment were identified.

Definitions

The three main aetiologies contributing to OA treatment were vascular disease, visceral surgical disease and trauma. Patients with acute intestinal ischaemia due to occlusion of the superior mesenteric artery were classified as having vascular disease, whereas patients with non-occlusive mesenteric ischaemia or no clear cause of mesenteric ischaemia were classified as having visceral disease. Fluid overload was calculated as bodyweight before initiation of OA treatment minus habitual bodyweight. Obesity was defined as body mass index of at least 30 kg/m².

Intra-abdominal pressure was measured intermittently as urinary bladder pressure through an indwelling catheter by means of the Foley manometer technique^7,8 (Holtech Medical, Charlottenlund, Denmark), before and repeatedly after initiation of OA treatment. Intra-abdominal hypertension and abdominal compartment syndrome were defined according to the World Society of the Abdominal Compartment Syndrome consensus definitions⁹. Abdominal compartment syndrome was defined as an intra-abdominal pressure exceeding 20 mmHg and organ dysfunction.

The Sequential Organ Failure Assessment (SOFA) score¹⁰ was used as an estimate of organ failure. Individual organ scores ranged from 0 to 4 points, and the maximum score was 24 points. The total score was calculated as the sum of the degree of respiratory (ratio of partial pressure of oxygen in arterial blood (Pao₂) to fraction of inspired oxygen (Fio₂)), coagulation (platelet count), hepatic (bilirubin levels), circulatory (mean arterial pressure and need for inotropic support), neurological and renal (creatinine levels or daily urinary output) dysfunction. The neurological score was not evaluated individually because of concerns about reliability¹⁰. The intra-abdominal pressure and SOFA score were evaluated immediately before and during the morning after initiation of OA treatment.

Classification of OA status¹¹ was performed at initiation of OA treatment and at fascial closure or in the event of death before closure, and changes were recorded in-between, with documentation of the most serious grade. Grade 1A was defined as clean and 1B as contaminated OA without adherence between bowel and abdominal wall or fixity/lateralization of the abdominal wall. Grade 2A was a clean OA developing fixity/lateralization of the abdominal wall not permitting closure in the midline, and 2B a contaminated OA developing fixity/adherence. Grade 3 was complicated by fistula formation and grade 4 was a frozen OA that could not be closed surgically without abdominal wall reconstruction.

Vacuum-assisted wound closure and mesh-mediated fascial traction

The technique has been described previously⁵. Patients were initially treated with VAWC alone, to avoid prolonging the primary laparotomy as part of a damage control strategy¹. Polypropylene mesh was applied at the first redressing after 2–3 days. The 30 × 30-cm mesh (Prolene®; Ethicon, Johnson & Johnson, Somerville, New Jersey, USA) was divided into two halves and sutured to the fascial edges on each side with a running 0 polypropylene suture (Prolene®). A VAWC system (V.A.C.® Abdominal Dressing System; KCI, San Antonio, Texas, USA) was applied; the perforated polyethylene sheet with a central thin polyurethane sponge was placed intra-abdominally, covering the viscera and tucked under the abdominal wall far out laterally on both sides. The two mesh halves were then sutured in the midline with a running 0 polypropylene suture, ventral to the polyethylene sheet. The thick polyurethane sponge was placed on top of the polypropylene mesh, and the wound was covered with occlusive self-adhesive thin polyethylene sheets (Fig. 1). A continuous or intermittent topical negative pressure of 50–150 mmHg was applied according to the surgeon's preference. A reason for use of lower pressure was ongoing haemorrhage.

Fig. 1

Vacuum-assisted wound closure and mesh-mediated fascial traction technique: 1, bowel; 2, visceral protective layer; 3, abdominal wall; 4, abdominal wall fascia; 5, polypropylene mesh, consisting of two mesh halves, sutured to the fascia laterally and to each other in the midline; 6, two pieces of polyurethane foam placed on top of the mesh and subcutaneously between the wound edges; 7, tubing set with an interface pad attached to an opening in the self-adhesive drapes and connected to the vacuum source

The VAWCM system was changed and the mesh tightened under general anaesthesia every 2–3 days. Dressing changes without mesh tightening were rarely performed. Finally, the mesh was removed after cutting the running polypropylene suture in the fascial edges on each side. The fascia was then closed with a running 0 polydioxanone suture (PDS II®; Ethicon), by means of a standardized suturing technique with a suture length to wound length ratio of at least 4 : 1¹². Successful delayed primary fascial closure was defined as complete closure of the whole length of the incised fascia.

Statistical analysis

Continuous variables were expressed as median (range) unless indicated otherwise, and analysed by means of Mann–Whitney U, Wilcoxon signed rank or Kruskal–Wallis test, as appropriate. Discrete variables were analysed with Pearson's χ² test, Fisher's exact test or Kendall's τ-b test, as appropriate. Variables associated with failure of fascial closure or in-hospital mortality in univariable analysis (P < 0·100) were entered into a multivariable binary logistic regression analysis, and significant associations were expressed in terms of odds ratio (OR) with 95 per cent confidence interval. Fascial closure was analysed on the basis of intention to treat and per protocol, because failure of fascial closure was highly associated with death in the intention-to-treat analysis. P < 0·050 was considered significant. All statistical analyses were performed using SPSS® version 17.0 (SPSS, Chicago, Illinois, USA).

Results

Among 151 patients treated with an OA, 111 received VAWCM treatment and were enrolled in the study. Reasons for exclusion are shown in Appendix S1 (supporting information). There were 81 men (73·0 per cent) and 30 women (27·0 per cent) with a median age of 68 (20–91) years. The median body mass index was 25·1 (19·4–41·5) kg/m² for men and 23·6 (16·1–38·9) kg/m² for women. The main disease aetiologies contributing to the OA were vascular (45, 40·5 per cent), visceral surgical disease (57, 51·4 per cent) and trauma (9, 8·1 per cent) (Table S1, supporting information). In all, 26 patients (23·4 per cent) had either primary or secondary acute mesenteric ischaemia. Abdominal infection resulting from intra-abdominal bacterial contamination was present in 40 patients (36·0 per cent). All patients had a primary disease or injury in the abdominopelvic region, except one who had a decompression laparotomy owing to abdominal compartment syndrome following stent-graft placement for a thoracic acute type B aortic dissection.

Indications for open abdomen treatment

The indications for OA treatment may have been multiple, but the main reasons were: fascial closure not possible (77, 69·4 per cent), documented intra-abdominal hypertension (22, 19·8 per cent) or abdominal compartment syndrome (22, 19·8 per cent), need for abdominal cavity drainage owing to infection (29, 26·1 per cent) or planned relaparotomy for assessment of bowel viability (14, 12·6 per cent). Abdominal compartment syndrome was found in 22 of 46 patients who underwent intra-abdominal pressure measurement before OA treatment. The abdomen was left open at primary or secondary operations in 33 (29·7 per cent) and 78 (70·3 per cent) patients respectively.

Effect of initiation of open abdomen treatment on intra-abdominal pressure

The median intra-abdominal pressure before OA treatment in 46 patients was 20 (9–43) mmHg, which decreased significantly to 11 (5–19) mmHg after initiation of OA treatment (P < 0·001). The intra-abdominal pressure before OA treatment was at least 12 mmHg in 44 patients. Changes in intra-abdominal pressure before and after abdominal decompression according to the grade of intra-abdominal hypertension before initiation of OA treatment are shown in Fig. 2. Among the 22 patients with abdominal compartment syndrome vascular disease was more common than visceral surgical disease (13 versus 6 patients; P = 0·050). Ten of 13 vascular patients with abdominal compartment syndrome had undergone surgery for an AAA.

Fig. 2

Intra-abdominal pressure before and after abdominal decompression. Median values (horizontal line within box), interquartile range (box), and range (whiskers) excluding outliers (○) and extremes (*) are shown

Effect of initiation of open abdomen treatment on organ failure

SOFA scores before OA treatment did not change over the years of study (P = 0·227). The median SOFA score was 8 (0–16) both before and after initiation of OA treatment (P = 0·854). In the subgroup of 44 patients with intra-abdominal hypertension the median SOFA score was 10 (2–16) before as well as after initiation of OA treatment (P = 0·097). The median Pao₂/Fio₂ ratio was 25·4 (6·2–67·0) kPa before treatment, increasing to 30·4 (7·7–67·0) kPa after initiation of OA treatment (P = 0·003). The Pao₂/Fio₂ ratio increased significantly among patients with intra-abdominal hypertension (41 patients; P = 0·008). Platelet count (P = 0·543), circulatory score (P = 0·917) and creatinine levels (P = 0·361) remained unchanged after initiation of OA treatment, whereas bilirubin levels increased significantly (P < 0·001).

Vacuum-assisted wound closure and mesh-mediated fascial traction treatment

The median fascial diastasis immediately after initiation of OA treatment was 17 (5–40) cm. The median duration of VAWC was 14 (4–87) days, with VAWCM for 12 (2–84) days. The duration of OA treatment decreased over the study interval (P = 0·013). The median number of mesh-tightening procedures was 4 (0–10). VAWCM therapy was applied in 33 patients with new bowel anastomoses and/or a new ileostomy (18) and/or colostomy (32) after bowel surgery. Topical negative pressure was continuous in 102 patients (91·9 per cent) and intermittent in nine (8·1 per cent). Topical negative pressures applied in the continuous mode were 0 mmHg (1 patient), 50 mmHg (12), 75 mmHg (17), 100 mmHg (15), 125 mmHg (47) and 150 mmHg (10). One patient with haemophilia and a severe risk of rebleeding was treated with 0 mmHg during most of the treatment time. Negative pressures applied in the intermittent mode were 50 mmHg (6 patients), 75 mmHg (2) and 125 mmHg (1). The mesh was released temporarily in one patient with recurrent abdominal compartment syndrome, owing to the development of severe Clostridium difficile colitis.

Classification of open abdomen

OA at the start of treatment was classified as grade 1A (67 patients, 60·4 per cent), 1B (42, 37·8 per cent), 2A (1, 0·9 per cent) and 3 (1, 0·9 per cent); at the end of treatment (fascial closure or death) it was grade 1A (83, 74·8 per cent), 1B (9, 8·1 per cent), 2A (3, 2·7 per cent), 3 (8, 7·2 per cent) and 4 (8, 7·2 per cent) (P < 0·001). The most serious OA grade recorded in each patient was 1A (53, 47·7 per cent), 1B (32, 28·8 per cent), 2A (3, 2·7 per cent), 3 (15, 13·5 per cent) and 4 (8, 7·2 per cent). The OA grade at the end of the treatment was improved in 28 patients (25·2 per cent), unchanged in 62 (55·9 per cent) and worsened in 21 (18·9 per cent). Among 62 patients with an unchanged grade, 55 patients had OA grade 1A at the start and end of treatment. The OA status at the end of treatment was associated with failure of fascial closure (P < 0·001) and in-hospital mortality (P < 0·001). Furthermore, change to a worse OA grade and the highest OA grade recorded in each patient were associated with failure of fascial closure (both P < 0·001) and with in-hospital mortality (P = 0·002 and P = 0·007 respectively).

Intention-to-treat analysis of fascial closure

Complete delayed primary fascial closure was achieved in 85 (76·6 per cent) of the 111 patients. Sixteen patients died with an OA before fascial closure was possible. Cartilage–bone-like formation in close proximity to the xiphoid process in the upper part of the fascial edges precluded complete upper fascial closure in two patients, who required later reconstructions, whereas excision of cartilage in the lower part of the wound was required before fascial closure in another patient. Eight patients underwent abdominal wall reconstruction with a polypropylene mesh at abdominal closure owing to remaining fascial diastasis. No patient treated with VAWCM had a large incisional ventral hernia remaining for secondary granulation of the wound and later repair. The median suture to wound length ratio, measured in 63 patients, was 5·5 (3·2–17·1). The SOFA score before OA treatment (84 patients; P = 0·666), fluid overload (86 patients; P = 0·422) and volume of blood transfusion (99 patients; P = 0·781) were not associated with failure of fascial closure. Results of univariable analysis of are shown in Table 1. In multivariable binary logistic regression analysis including VAWC treatment for more than 21 days, intestinal fistula, renal replacement therapy and intensive care unit (ICU) stay of at least 21 days, only intestinal fistula remained as an independent factor associated with failure of fascial closure (OR 8·55, 1·47 to 49·72; P = 0·017).

Table 1

Factors associated with failure of fascial closure in intention-to-treat analysis

			Univariable analysis of failure of fascial closure
	No. of patients*	No. with fascial closure*	Odds ratio†	P‡
All patients	111	85 (76·6)
Age ≥ 75 years	25 (22·5)	19 of 25 (76)	1·04 (0·37, 2·96)	0·938
Sex ratio (M : F)	81 : 30	63 : 22	0·79 (0·30, 2·06)	0·623
Obese	15 of 75 (20)	11 of 15 (73)	1·32 (0·36, 4·82)	0·679
Repair of ruptured or complicated AAA	30 (27·0)	24 of 30 (80)	0·76 (0·27, 2·13)	0·604
Abdominal infection	40 (36·0)	32 of 40 (80)	0·74 (0·29, 1·89)	0·523
Before open abdomen treatment
IAH 12–20 mmHg	22 of 46 (48)	16 of 22 (73)	1·33 (0·38, 4·72)	0·655
Abdominal compartment syndrome	22 of 46 (48)	14 of 22 (64)	1·71 (0·48, 6·09)	0·403
After initiation of open abdomen treatment
SOFA score decreased by ≥ 2	16 of 84 (19)	11 of 16 (69)	1·09 (0·34, 3·55)	0·885
IAP decreased by ≥ 10 mmHg	24 of 45 (53)	15 of 24 (63)	1·92 (0·52, 7·05)	0·322
VAWC treatment < 7 days	9 (8·1)	7 of 9 (78)	0·93 (0·18, 4·77)	0·929
VAWC treatment ≥ 14 days	59 (53·2)	40 of 59 (68)	3·05 (1·16, 8·02)	0·020
VAWC treatment ≥ 21 days	37 (33·3)	23 of 37 (62)	3·15 (1·27, 7·79)	0·011
Ventilator ≥ 14 days	43 of 106 (40·6)	30 of 43 (70)	1·67 (0·68, 4·07)	0·259
Renal replacement therapy	38 of 110 (34·5)	25 of 38 (66)	2·36 (0·96, 5·80)	0·058
ICU stay ≥ 21 days	48 of 107 (44·9)	32 of 48 (67)	2·45 (0·99, 6·07)	0·049
Intestinal changes
Intestinal fistula	8 (7·2)	2 of 8 (25)	12·45 (2·34, 66·34)	< 0·001
Bowel resection	46 (41·4)	32 of 46 (70)	1·93 (0·80, 4·69)	0·142
Bowel anastomosis	33 (29·7)	22 of 33 (67)	2·10 (0·84, 5·25)	0·109
Ileostomy	18 (16·2)	14 of 18 (78)	0·92 (0·28, 3·09)	0·895
Colostomy	32 (28·8)	27 of 32 (84)	0·51 (0·17, 1·50)	0·217
Any stoma	44 (39·6)	36 of 44 (82)	0·60 (0·24, 1·54)	0·291

Values in parentheses are

*

percentages and

†

95 per cent confidence intervals.

AAA, abdominal aortic aneurysm; IAH, intra-abdominal hypertension; SOFA, Sequential Organ Failure Assessment; IAP, intra-abdominal pressure; VAWC, vacuum-assisted wound closure; ICU, intensive care unit.

‡

χ² test.

Per-protocol analysis of fascial closure

The fascial closure rate among the 95 patients alive at the time of closure was 89 per cent (85 of 95). When factors associated with fascial closure in the univariable analysis (Table 1) were included in a multivariable analysis, VAWC treatment lasting for at least 14 days was independently associated with failure of fascial closure (OR 5·47, 1·01 to 29·55; P = 0·048). When VAWC treatment was analysed as a continuous variable, a longer VAWC treatment period was associated with failure of fascial closure (P = 0·022).

Intensive care

Ninety-three patients (83·8 per cent) had ventilator-assisted respiration at some stage of the treatment. Renal replacement therapy was needed in 38 (34·5 per cent) of 110 patients and inotropic support in 86 (78·2 per cent).

Complications

Complications during and after VAWCM treatment are summarized in Table 2. Possible VAWCM-induced intestinal fistulas occurred in eight patients (7·2 per cent), seven during and one after VAWCM treatment. Seven were enteroatmospheric and one was a colocutaneous fistula. The main factors associated with the intestinal fistula were intestinal ischaemia (7 patients), multiple surgical procedures on the bowel (7) and new bowel anastomoses (8).

Table 2

Complications

	n
During VAWCM treatment
Intestinal or infection problems
Intestinal fistula	7
Leakage of stool from colostomy to abdomen	2
Leakage of stool from rectal stump	2
Dehiscence of colostomy	1
Intra-abdominal abscess	1
Vascular prosthesis (stent-graft) infection	1
Bleeding
From rectus muscle	2
From liver fracture	1
Wound disturbance
Cartilage–bone formation in abdominal incision	3
Gastric feeding tube complicating VAWC dressing	1
changes
Anaesthesia-related problems
Cardiac arrest during initiation of anaesthesia before	1
VAWC dressing change
After VAWCM treatment
Intestinal or deep infection problems
Intestinal fistula	1
Intra-abdominal abscess	4
Mesh infection after abdominal wall reconstruction	1
Vascular prosthesis infection (femorofemoral	1
crossover graft)
Aortoenteric fistula	1
Wound infection
Superficial	10
Deep	1
Wound dehiscence needing resuture	1
Total no. of complications	42
Total no. of patients with complications	29

VAWC(M), vacuum-assisted wound closure (and mesh-mediated fascial traction).

Leakage of stool from a staple line occurred in two patients as a result of overt ischaemia of the rectal stump; these complications were considered by the study investigators to be unrelated to VAWCM. Nine perforations/fistulas occurred before initiation of VAWC treatment. In five patients this was due to intestinal perforation and bowel necrosis (2), bile leakage from a hepaticojejunostomy (1), perforation during surgery for bowel obstruction (1) and leakage from a gastrostomy (1); the latter three fistulas were self-limiting during VAWCM therapy. Three patients had a fistula from the urinary tract to the OA after surgery (2) and trauma (1). One patient had acute pancreatitis and developed a fistula to the pleural cavity.

Prognostic factors for in-hospital mortality

The in-hospital mortality rate was 29·7 per cent (33 of 111). Evaluation of factors associated with in-hospital mortality is shown in Table 3. The continuous variables age (P = 0·002), duration of ventilator-assisted respiration (P = 0·001), length of renal replacement therapy (P = 0·006), ICU stay (P = 0·006) and high fluid overload (P = 0·013) were associated with death. A high SOFA score before OA treatment showed a trend towards an association with mortality (P = 0·082). In multivariable logistic regression analysis including age, time on ventilator, duration of renal replacement therapy, ICU stay, fluid overload, SOFA score before OA treatment, occurrence of intestinal ischaemia, any stoma, failure of fascial closure and intestinal fistula, only age (OR 1·21, 1·02 to 1·43; P = 0·027) and failure of fascial closure (OR 44·50, 1·13 to 1748·52; P = 0·043) were independently associated with in-hospital mortality.

Table 3

Prognostic factors for in-hospital death

			Univariable analysis
	No. of patients*	No. of in-hospital deaths*	Odds ratio†	P‡
All patients	111	33 (29·7)
Age ≥ 75 years	25 (23)	11 of 25 (44)	2·29 (0·90, 5·77)	0·080
Sex ratio (M : F)	81 : 30	22 : 11	0·64 (0·26, 1·57)	0·332
Obese	15 of 75 (20)	3 of 15 (20)	0·54 (0·14, 2·14)	0·380
Repair of ruptured or complicated AAA	30 (27)	12 of 30 (40)	1·90 (0·79, 4·61)	0·153
Intestinal perforation	35 (31·5)	7 of 35 (20)	0·48 (0·18, 1·25)	0·133
Intestinal ischaemia	26 (23·4)	13 of 26 (50)	3·25 (1·30, 8·14)	0·012
Before VAWC treatment
SOFA score ≥ 14	8 of 84 (10)	5 of 8 (63)	3·40 (0·75, 15·38)	0·112
Fluid overload ≥ 10 kg	48 of 86 (56)	16 of 48 (33)	2·21 (0·80, 6·12)	0·125
IAH 12–20 mmHg	22 of 46 (48)	7 of 22 (32)	0·55 (0·16, 1·84)	0·333
Abdominal compartment syndrome	22 of 46 (48)	10 of 22 (45)	1·67 (0·50, 5·50)	0·402
After initiation of VAWC
SOFA score decreased ≥ 2	16 of 84 (19)	4 of 16 (25)	0·57 (0·17, 1·97)	0·377
IAP decreased ≥ 10 mmHg	24 of 45 (53)	11 of 24 (46)	1·69 (0·50, 5·68)	0·395
VAWC treatment ≥ 14 days	59 (53·2)	17 of 59 (29)	0·91 (0·40, 2·06)	0·822
Failure of fascial closure	26 (23·4)	18 of 26 (69)	10·50 (3·85, 28·61)	< 0·001
Ventilator ≥ 14 days	43 of 106 (40·6)	20 of 43 (47)	3·34 (1·42, 7·87)	0·006
Renal replacement therapy	38 of 110 (34·5)	18 of 38 (47)	3·42 (1·46, 8·00)	0·005
ICU stay ≥ 21 days	48 of 107 (44·9)	20 of 48 (42)	2·53 (1·09, 5·86)	0·031
Management of the bowel
Intestinal fistula	8 (7·2)	7 of 8 (88)	20·73 (2·43, 176·54)	0·006
Bowel resection	46 (41·4)	17 of 46 (37)	1·80 (0·79, 4·09)	0·163
Bowel anastomosis	33 (29·7)	13 of 33 (39)	1·88 (0·80, 4·47)	0·150
Ileostomy	18 (16·2)	4 of 18 (22)	0·63 (0·19, 2·08)	0·449
Colostomy	32 (28·8)	6 of 32 (19)	0·44 (0·16, 1·21)	0·113
Any stoma	44 (39·6)	9 of 44 (20)	0·46 (0·19, 1·12)	0·087

Values in parentheses are

*

percentages and

†

95 per cent confidence intervals.

AAA, abdominal aortic aneurysm; VAWC, vacuum-assisted wound closure; SOFA, Sequential Organ Failure Assessment; IAH, intra-abdominal hypertension; IAP, intra-abdominal pressure; ICU, intensive care unit.

‡

χ² test.

Discussion

The fascial closure rate among 111 patients in the present study was unexpectedly high: 76·6 per cent in the intention-to-treat and 89 per cent in the per-protocol analysis. The present cohort comprised a clinically representative mixture of elderly patients, most of whom underwent AAA repair, operation for gastrointestinal perforation with deep abdominal infection or surgery for intestinal ischaemia. In comparison, VAWC treatment without mesh has been reported to facilitate fascial closure in approximately 70 per cent of trauma patients with a mean age below 40 years^4,13.

The new classification system¹¹ of the severity and changes of OA status over time was found to be associated with failure of fascial closure in the present study. Indeed, a clean OA without bowel lesions throughout the OA period has been reported to be associated with fascial closure and survival¹⁴. The intestinal fistula rate in the present series was 7·2 per cent, and it remains speculative whether the VAWCM system contributed to the development of intestinal fistula in any of these patients. A systematic review of 251 patients treated with an OA found that VAWC was one of the best techniques for achieving fascial closure with a low frequency of intestinal fistula (2·9 per cent)¹⁵. Bee and colleagues⁶ reported a high rate of intestinal fistula (21 per cent) and intra-abdominal abscess (44 per cent) after topical negative pressure treatment of OA⁶. In that study, however, two different methods were used to apply negative pressure. Only five of 31 patients were treated by VAWC, whereas the traditional vacuum pack system suggested by Brock and co-workers¹⁶ was used in the remaining patients. With both of these temporary closure device systems, the thin perforated polyethylene sheet was extended only beneath the fascial edges, which may partly explain the poor clearance of bacterial contamination from the abdominal cavity and the high rate of intra-abdominal abscess. The poor coverage of bowel with the protective plastic sheet may also have exposed the patient to an unnecessary increased risk of enteroatmospheric fistula. Placement of a gastric or jejunal feeding tube probably contributed to the majority of the reported intestinal fistulas in this study⁶. In agreement, several authors have warned against combining gastric or jejunal feeding tubes with OA treatment¹⁷ as efforts to keep the abdomen open also prevent adherence around the catheterized stoma, with a higher risk of bowel leakage. The authors concluded that enteral feeding should be administered via a nasojejunal instead of a jejunal tube in patients treated with an OA⁶.

In the present study complications during and after VAWCM treatment were attributed mainly to the underlying pathology and the subsequent development of infectious complications. In particular, patients with intestinal ischaemia undergoing bowel resection and deferred primary bowel anastomosis were at increased risk of developing enteroatmospheric fistula. The rate of enteroatmospheric fistula might have been reduced if diverting stomas had been used more frequently, but the mortality rate would probably have remained high owing to short bowel syndrome associated with high-output stomas¹⁸.

Despite the investigators' awareness of the importance of surgeon continuity in changing dressings, it was often not possible to organize dressing changes during office hours. Instead, they were frequently done in the evening and overnight, often by junior surgeons, although all participating surgeons at the four hospitals were instructed in the intended treatment technique. Suction of stools from the stoma over the skin to the nearby OA wound occurred in two patients, which might have been prevented by creation of the stoma at an appropriate distance from the OA wound, and by isolation of the skin bridge with a strip of adhesive gel on both sides. Hence, there was a learning curve in wound care and dressing changes. The development of cartilage–bone masses in the upper and lower part of the abdominal incision¹⁹ interfered with fascial closure in a few patients, and it is unclear whether VAWCM facilitated this process.

A concern with the VAWCM technique is the traction force and trauma to the fascial edges generated in the suture line between the fascial edges and the interposed polypropylene mesh, and the risk of future ventral hernia formation. The frequency of abdominal wall hernia will be examined by computed tomography at 1 year and reported in a follow-up investigation.

The SOFA score has been used previously to evaluate physiological changes following decompressive laparotomy²⁰. There was a clear decrease in intra-abdominal pressure after decompression among patients with documented abdominal compartment syndrome and intra-abdominal hypertension, but SOFA scores did not change. Similar findings were reported by De Waele and colleagues²¹ in a collective review of 250 patients. Different underlying diseases respond differently to decompressive laparotomy. For example, the procedure seems to have a poor effect on respiratory and circulatory scores as well as the overall SOFA score in patients with acute pancreatitis²². The results from the present study do not support use of the SOFA score to evaluate physiological changes after decompressive laparotomy, in contrast to previous recommendations²⁰. A prospective multicentre trial has been initiated by the World Society of the Abdominal Compartment Syndrome to study a more refined scoring system.

The purpose of the present study was to evaluate the VAWCM method. The ideal study design would have been a randomized controlled trial including one or two control groups for evaluation of fascial closure, survival, intestinal fistula and abdominal wall hernia. There are problems in conducting such a trial, however. It is difficult to obtain informed consent from the patient for randomization and ethical approval may be difficult to obtain. Furthermore, a substantial proportion of patients, as in the present study, are left with an OA after primary laparotomy without the possibility of obtaining baseline data such as intra-abdominal pressure and SOFA score. OA treatment should not be initiated unless there is an anticipated major advantage to the patient as it is associated with increased morbidity, including an increased risk of bowel injury, paralytic ileus and infection. It may even increase the risk of major haemorrhagic complications in patients with acute pancreatitis²³ or severe coagulopathy^24,25. However, better knowledge of the hazards of increased intra-abdominal pressure has resulted in more patients being treated with an OA, resulting in improved survival²⁶, at the expense of the development of intestinal fistula and incisional hernia.

Acknowledgements

The authors declare no conflict of interest.