MANAGEMENT OF THE BURST ABDOMEN Robert Tasevski Royal Melbourne Hospital OVERVIEW · Definition · Incidence · Clinical Manifestation · Risk Factors For Abdominal Wound Dehiscence · Pre-Operative Factors · Operative Factors · Post-Operative Factors · Treatment · Non-operative Treatment · Operative Treatment · Retention Sutures · The Uncloseable Abdomen DEFINITION · Also known as abdominal wound dehiscence, wound failure, wound disruption, evisceration, and eventration. · Describes partial or complete postoperative separation of an abdominal wound closure with protrusion or evisceration of the abdominal contents. · Wound dehiscence and incisional hernia are part of the same wound failure process; it is timing and healing of the overlying skin that distinguishes the two. The full healing of the skin incision is used to make a convenient distinction between wound dehiscence and incisional hernia. Dehiscence of the wound occurs before cutaneous healing, while incisional hernias lie under a well-healed skin incision. INCIDENCE · Wound dehiscence continues to be a major complication of abdominal surgery despite significant progress in operative and perioperative care over the last few decades. · Accompanied by high morbidity and mortality. · Reported incidence varies between 0.2% to 6%. · Associated with mortality rates between 10% and 40%. Carlson MA. Acute Wound Failure. Surgical Clinics of North America 1997; 77: 607-636. · Incidence of wound dehiscence in 12 studies before 1940 (>71,000 incisions): 0.4% (range 0.24% - 3.0%) · Incidence of wound dehiscence in 34 studies published between 1950 and 1984 (>320,000 incisions): 0.59% (range 0.24% - 5.8%) · Incidence of dehiscence in 18 studies published since 1985 (18,133 incisions): 1.2% · Does not demostrate a downward trend compared with earlier reviews. · Increasing number of complex operations and the ageing patient population may be important in this respect. Carlson MA. Acute Wound Failure. Surgical Clinics of North America 1997; 77: 607-636 CLINICAL MANIFESTATION · Dehiscence usually declares itself 7-14 days post-op. · Wound disruption may occur without warning. · May manifest following straining or removal of the sutures. · Patient often notes a “ripping sensation” or a feeling that “something has given way”. · Impending dehiscence of the abdominal wall is often preceded by the appearance of a salmon-pink serous discharge from the wound. This is seen in up to 85% of cases. RISK FACTORS FOR ABDOMINAL WOUND DEHISCENCE · There are many factors that may contribute to wound dehiscence. These may conveniently be divided into pre- operative factors, operative factors, and post-operative factors. · Pre-operative factors essentially relate to the pre-operative condition of the patient and patient characteristics. · Operative factors relate to the type of incision and the technique of wound closure. · Post-operative factors essentially relate to post-operative complications. Pre-Operative Factors · Male Sex: Among patients with wound dehiscence men outnumber women by at least 2 to 1 · Age: The incidence in the “aged” is higher than that in the “young”. Advanced age has been variably defined (over 50 to 65 years). <45 y.o. dehiscence occurs in 1.3% >45 y.o. dehiscence occurs in 5.4% (Schwartz et al, Principles Of Surgery) Advanced age is often accompanied by medical problems that also may affect healing, so it is difficult to discern its importance as a risk factor. · Emergency Operation: Has been shown to be a risk factor for dehiscence in some studies. May be related more to haemodynamic instability than too the unscheduled procedure. · Obesity: Most studies that evaulate obesity as a risk factor for burst abdomen report no association. Brolin RE. Prospective, Randomised Evaluation of Midline Fascial Closure in Gastric Bariatric Operations. The American Journal of Surgery 1996; 172; 123-126. · Prospective, randomised, trial which compared two methods of closure of the linea alba after gastric restrictive operations performed for treatment of morbid obesity. · 229 patients over a 6 year period. · 2 out of 229 patients (0.9%) suffered an acute dehiscence. · This figure is similar too that reported in other prospective studies of wound closure in which obesity was not a dependent variable. · Diabetes: Prior to the avaliability of insulin wounds in insulin- deficient diabetes failed at a rate of 25%, usually secondary to wound sepsis. The introduction of insulin improved these results. It now appears that well controlled diabetes is not a risk factor for fascial dehiscence. · Renal failure: Increased risk for burst abdomen attributable to uraemia is speculative. Uraemia introduced malnutritution may actually be the mechanism involved. · Jaundice: It is unclear whether the defect in wound healing associated with jaundice is secondary to hyperbilirubinacmia, malnutrition associated with chronic biliary obstruction, or the deficiencies associated with liver disease. · Anaemia: Low haemoglobin has been found to be a risk factor in some studies, but not in others. · Malnutritution: · Protein deficencies: Hypo-albuminaemia can be used as a marker of malnutritution. · Vitamin C: is critical for strength gain in healing wounds. Sub-clinical vitamin c deficency has been assumed to impair healing and predispose to wound failure. Sub-clinical vitamin c deficency is associated with an eightfold increase in the incidence of wound dehiscence. Vitamin C supplementation seems reasonable in malnourished surgical patients. · Zinc deficency: the role of zinc in wound healing has not been resolved. Zinc is a co-factor for various enzymatic and mitotic proceses. · Corticosteriods: Steriods, administered topically or systemically, have a deleterious effect on wound healing, interfering with inflammation, macrophage function, capillary proliferation, and fibroplasia. Operative Factors Incision type: • The rate of dehiscence is higher in midline incisions than in transverse incisions. • Midline incision is in”non-anatomic”. It cuts across the aponeurotic fibres, as opposed to the transverse incision which cuts paralell to the fibres. • Contraction of the abdominal wall causes laterally directed tension on the closure. In the midline incisions, this may cause the suture material to cut through by separation of the tranversily orientated fibres. Conversely, in the transverse incision, the fibres are apposed on contraction. • However, the midline incision is the most versatile. A prospective trial involving non urgent abdominal procedures comparing transverse, midline and paramedian incisions, performed by Ellis and co workers, did not demonstratte any significant difference in the rate of wound failure (Ellis H, Colridge-Smith PD, Joyce AD. Abdominal incisions - vertical of transverse? Postgrad Med J 1984; 60: 407 - 410). Closure: Mass versus Layered Closure: · Closure of the abdominal wall in layers has been the traditional approach. · Data have been published that suggest that mass closure (all layers of the abdominal wall taken together) is equivelent to or better than layered closure in preventing dehiscence. Weiland DE, Bay RC, Del Sordi S. Choosing the Best Abdominal Closure by Meta-analysis. American journal of surgery 1998; 176: 666 - 670. • A meta-analysis of 12,249 patients with abdominal wound closures from 9 countries was performed. • Outcome comparsions of infection rates, hernia formation, and dehiscences were made between mass versus layered closures. • Mass closures produced significantly less hernias and dehiscences when compared with layered closures (P = .02) • Mass closure is currently favoured because of its safety, efficacy, and speed. · Interrupted versus Continuous Sutures: · A multicentre, randomized, prospective trial compared interrupted versus continuous polyglycolic acid (Dexon) suture closure of midline abdominal incisions. (Fagniez PL, Hay JM, Lacaine F, et al. Archives of Surgery 1985; 120: 1351). · 3135 patients · overall dehiscence rate was 1.6% in the continuous suture group and 2% in the interrupted suture group (not statistically significant) · Several smaller randomised trials comparing continuous with interrupted also reveal no difference in the incidence of wound disruption. · Several technical variations of the interupted stitch, including the interrupted ‘figure of eight’, ‘far-and-near’ technique, or interrupted “Smead-Jones’ technique did not improve outcomes. · Continuous suture is a reasonable closure technique because of its safety, efficacy, and speed. • Peritoneal Closure • Suturing the peritoneum is not vital to prevent wound dehiscence. • Randomised trials have shown no difference in the wound disruption rate when one-layer closure (peritoneum not sutured) and two-layer closure are compared in paramedian and midline incisions. • The peritoneal defects heal by simultaneous regeneration of the layer over the entire defect, not an incremental advancement from the wound edge, as is seen with skin. • Suture Materials • Numerous prospective and retrospective studies have compared various suture materials in abdominal wound closure. • The majority of prospective, randomised studies have shown no difference in the overall incidence of wound complications between the various absorbable and nonabsorbable sutures. • So the choice seems to be one of personal preference. • It may be wise, however, to use a nonabsorbable monofilament in the patient who has an excessive number of risk factors for delayed healing. Van’t Riet M, Steyerberg EW, Nellensteyn J, Bonjer HJ, Jeekel J. Meta-analysis of techniques for closure of midline abdominal incisions. 2002 British Journal of Surgery; 89: 1350-1356. · Meta-analysis of 15 prospective, randomised, controlled trials with at least 100 patients comparing different suture materials and/or suture techniques for closure of a midline incision. · 6566 patients in total · No difference in wound dehiscence between slowly absorbing continuous suture (eg polyglyconate (Maxon), polydiaxanone (PDS)) and nonabsorbing continuous suture (eg nylon (Ethicon), polypropylene (Prolene)). · Increased incidences of prolonged wound pain (P<0.005) and suture sinus (P=0.02) were noted after the use of nonabsorbable, compared with slowly absorbable, sutures. · Comparison of continuous and interrupted sutures found no differences in incidence of wound dehiscence. · Conclusion: Slowly absorbable continuous sutures appear to be the optimal method of fascial closure. •Size of Tissue Bite and Suture Length-to-Wound Length Ratio · Suture length-to-wound length ratio (SL:WL) influences the rate of wound dehiscence. · Most studies support the use of a SL:WL of greater than 4:1 for continuous mass closure. · This is achieved if both the stitch interval and the tissue bite are 1cm (SL:WL is 4.1:1). Increasing the bite to 2cm produces a ratio of 8.1:1. · A SL:WL of less than 4:1 is associated with an increased risk of abdominal dehiscence and the later development of incisional hernia. Israelsson LA, Jonsson T, Knutsson A. Suture Technique and Wound Healing in Midline Laparotomy Incisions. European Journal of Surgery 1996; 162: 605-609 • Prospective clinical trial from county hospital in Sweden • 467 patients who underwent midline laparotomy. • Looked at influence of suture technique on healing of midline laparotomy wounds. • Concluded that suture technique affects both early and late wound complications; and particularly that the rate of incisional hernia is lower if the suture length-to-wound length ratio is 4 or more. Post-Operative Factors • Elevation of Intra-Abdominal Pressure • This may be due to: coughing vomitting ileus urinary retention • Frequently cited as an instigator of dehiscence. • Wound Infection • Its role is not entirely clear. • Dehiscence often occurs before wound infection is established • The additional degree of inflammation that a modest wound infection produces may hasten the healing process. • Rarely, disintegration of the fascia froma necrotising infection may lead to dehiscnence. · Radiation Therapy · Both in the past and perioperatively · Interferes with normal protein synthesis, mitosis, migration of inflammatory factors, and maturation of collagen. · Antineoplastic Agents. · Inhibit wound healing and delay gain in wound tensile strength. · Delay administration of an antineoplastic agent in a postoperative cancer patient until the acute healing phase is over (usually 2-3 weeks). TREATMENT · Management depends on the patient’s condition. Non-Operative Treatment · If patient very unstable, and there has been no evisceration, preferable to treat non-operatively. · Performed at bedside. · Involves either gauze packing of the wound or covering it with a sterile occlusive dressing. · Abdominal binder may be used to support disrupted abdominal wound. · Wound may subsequently contract to closure, or if the patient’s condition improves, delayed operative closure may be performed. · Hernia is a common sequela Operative Treatment · For most patients immediate re-operation is indicated · Most common technique is immediate resuture (usually with a mass closure) with the placement of retention sutures. · Pre-operative broad spectrum antibiotics should be given. · Free the omentum and bowel for a short distance on the deep surface of the wound on both sides. · Insert deep retention sutures · Then proceed with mass closure of the abdominal wall. Be certain to take deep bites of tissue, using plenty of suture material, and avoid excessive tension on the wound. · Close the skin fairly loosely and consider using a superficial wound drain. In the presence of gross wound sepsis, leave the skin open and pack. · Retention Sutures · There are a number of techniques, but the basic principles are: · use heavy non-absorbable suture eg. No 1 monofilament Nylon · wide interupted bites of at least 3cm from the wound edge and a stitch interval of 3cm or less. · either external (incorporating all layers peritoneum through to skin) or internal (all layers except skin) may be used. · internal retention sutures avoid producing an unsightly ladder-pattern scar, however they are unable to be removed subsequently (increased infection risk). · a buttress device is used to prevent suture erosion into the skin.eg. thread each suture through a short length (5-6cm) of plastic or rubber tubing. · do not tie too tightly · external retention sutures aree usually left in for at least 3 weeks. · The Uncloseable Abdomen · In a small number of patients it is inappropriate, technically unsafe or even impossible to close the abdominal wall primarily. · Conditions which may predispose to an uncloseable abdomen include: - major abdominal trauma - gross abdominal sepsis - retroperitoneal haematoma eg. post ruptured AAA - loss of abdominal wall tissue eg. necrotising fasciitis · Attempted closure may lead to sustined elevation of intra- abdominal pressure and subsequent abdominal compartment syndrome. · In certain cases (eg. if the cause is likely to resolve rapidly) it may be possible to temporarily close to abdomen by packing the wound and taking a further look in 24-48 hours · Mesh closure of the abdominal incision is usually indicated · the defect is bridged with one or two layers of a prosthetic mesh · the mesh is sutured in place with sutures that penetrate the full thickness of the abdiminbal wall · dressing changes and subsequent granulation tissue formation ultimately result in a surface that can be covered with a split-skin graft. · Different types of mesh are available but they all have their advantages and problems: · Absorbable mesh (polyglycolic acid eg. Dexon) · temporary closure · good for infected abdomen · subsequent incisional hernia inevitable · Polypropylene mesh (eg. Prolene, Marlex) · erosion into bowel and fistula formation · dense adhesion formation · quite tolerant of infection · PTFE (eg. Goretex) · soft and pliable · less adhesions to bowel · tolerates infection poorly · Once well enough and intestinal oedema has resolved, usually return to operating theatre for attempt at abdominal wall closure. Nagy KK, Fildes JJ, Mahr C, et al. Experience with Three Prosthetic Materials in Temporary Abdominal Wall Closure. American Surgeon 1996; 62: 331-335 · Retrospective study conducted at level 1 trauma centre. · 25 patients in study · Marlex associated with fistula in 3 out of 4 (75%) patients. · Dexon associated with development of large hernias as it expands under tension due to its knitted weave. · Advocate use of Goretex mesh - soft, flexible, compliant, does not stretch, invokes minimal inflammation and adhesions, no fistula formation in this study.