Difficult Infected Wound After Colorectal Surgery

Surgical wounds in normal, healthy individuals heal through an orderly sequence of physiologic events that include inflammation, epithelialisation, fibroplasia, and maturation. Mechanical failure or failure of wound healing at the surgical site can lead to disruption of the closure leading to seroma, hematoma, wound dehiscence or hernia. Other complications include surgical site infection and nerve injury.

c. Technique related risk factors for surgical site infection 4 (Table 2): Various surgical related factors affect wound healing differently.This includes both pre surgical patient preparation and post operative care.Intra operative procedures including the surgical techniques like excessive use of electrocautery, poor haemostasis and tissue trauma can adversely affect wound healing as can the length of the surgery.Insertion and duration of intra abdominal drains remains a controversial point.

Classification of abdominal wound infection
Surgical wound infection can be classified into different types based on various criteria 6 .a. Based on the depth and the site of the surgical wound infection, the three types are: 1. Superficial incisional surgical site infection: Involves skin and subcutaneous fat (Image 1).

Clinical manifestation and diagnosis
As with infection anywhere, surgical site infections present with localized erythema, induration, warmth, and pain at the incision site.Purulent wound drainage and separation of the wound may occur.Some patients will have systemic evidence of their infection such as fever and leukocytosis.Role of imaging is limited to those patients in whom there is a clinical suspicion of deep space infections or collections.Of the imaging modalities, Computed Tomography is the preferred modality for assessment.
Ultrasound may have a limited role in assessing deep space infections but can evaluate collections related to superficial wounds, particularly, if the clinical evaluation is difficult or inconclusive.

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Contemporary Issues in Colorectal Surgical Practice 118

Complication of SSI
In addition to the complications related directly to the wound, patients with SSI can have other complications based on their pre surgical risk factors and co morbidities that can adversely affect their long term outcome and prolong their convalescence.
These complications have been well documented and researched and include long hospital stay, increasing morbidity, SIRS -Sepsis -MOF and even death.

Management
Recent studies have shown the strong influence of the various risk factors that results in an increase in the incidence of surgical site infection.Thus, there has been a shift in the approach to the management of these patients with emphasis being placed on prophylaxis.

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Adequately identifying and correcting the various systemic co-morbidities thus optimising the pre-operative status and reducing the pre-operative risk for SSI.-This has shown to be as important as post-operative and intra-operative care.2. Encourage patients who use tobacco products to quit using or to abstain for 30 days prior to surgery 3. Have the patient shower or bathe with an antiseptic agent on at least the night before surgery 4. Follow strict standards for sterilizing instruments, disinfecting operating room, and air circulation 5. Do not routinely use vancomycin for prophylaxis if other agents are appropriate 6. Do not use UV radiation in the operating room for infection prophylaxis 7. Surgical staff who have draining skin lesions are excluded from duty 8. Surgical staff should wear sterile clothing and gloves 9. Surgical team hand hygiene to include keeping fingernails short, scrubbing with antiseptic to elbows for 2-5 min, using sterile towels 10.Use appropriate topical microbicides during surgery 11.Use proper surgical technique 12. Apply sterile dressing to incision for 24-48 hours postoperatively and wash hands before contact with surgical site 13.Perform hospital surveillance for surgical site infection

Definitive management
Definitive management of SSI depends on the type of infection.

Superficial incisional surgical site infection
Infected wounds are opened, explored, drained, irrigated, débrided and dressed open.
If fascial disruption is suspected, drainage should be performed in the operating room.
The severity of the infection determines the need for antibiotic therapy.Once the infection has cleared and granulation tissue is apparent, the wound can be closed secondarily.

Fascial dehiscence:
Fascial disruption is due to abdominal wall tension overcoming tissue or suture strength, or knot security as a result of infection or collection.It can occur either early or late in the postoperative period and can involve a portion of the incision (i.e, partial dehiscence) or the entire incision (i.e, complete fascial dehiscence).
The incidence of fascial disruption ranges from 0.4 to 3.5 % depending upon the type of surgery performed.Despite improved perioperative care and stronger suture materials, the incidence and morbidity of fascial dehiscence is largely unchanged.
When fascial disruption is suspected, wound exploration should be performed in the operating room.Complete fascial dehiscence is associated with a mortality rate of 10% and is a surgical emergency.At the bedside, a moist dressing is placed over the wound and a binder placed around the patient's abdomen to prevent evisceration on the way to the operating room.
Once opened, the wound is thoroughly debrided.Treatment options include either using VAC dressing or mass closure.Mass closure done with continuous or retention non-absorbable sutures is an option only if the intra-abdominal pressure and tissue oedema intraoperatively is not high.In such cases VAC dressing is the preferred treatment.

Prevention
Meta-analyses related to abdominal fascial closure suggest an optimal technique for closure of abdominal surgical wounds includes (8,9) :

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Use of a simple running technique  Use of #1 or #2 delayed absorbable monofilament suture  Use of mass closure to incorporate all layers of the abdominal wall (except skin)  Taking wide tissue bites (≥1 cm)  Use of a short stitch interval (≤1 cm)  Use of a suture length to wound length ratio of 4 to 1  Use of non-strangulating tension on the suture.

Organ/Space surgical site infection
One of the critical decisions in the surgical treatment of patients with severe peritonitis is whether to use an open-abdomen or a closed-abdomen technique.

Closed abdomen technique
The goal of the closed-abdomen technique is to provide definitive surgical treatment at the initial operation which saves the patient from repetitive trauma of anaesthesia and surgery.
Opting for this technique should be judicious in an unstable patient.

Open abdomen technique
VAC dressing and temporary closure with sponge or mesh are types of open abdomen techniques which are valuable tools for the management of patients with acidosis, hypothermia and coagulopathy.This is a very resource-intensive decision.
The goal of the open-abdomen technique is to provide easy, direct access to the affected area.Source control is achieved through repeated reoperations or through open packing of the abdomen.This technique may be well suited for initial damage control in extensive peritonitis.
The open-abdomen technique should also be considered in patients who are at high risk for the development of abdominal compartment syndrome (eg, patients with intestinal distension, extensive abdominal wall and intra-abdominal organ edema), because attempts to perform primary fascial closure under significant tension in these circumstances are associated with an increased incidence of multiple organ failure (eg, renal, respiratory), necrotizing abdominal wall infections, anastomotic leak, entero-cutaneous fistula and mortality.
Temporary closure of the abdomen to prevent herniation and contamination can be achieved by using various materials (Table 5): 1. Self-adhesive impermeable membrane dressings using sponge and opsite.Though it is in inexpensive and easy to apply, the major disadvantage is difficulty in maintaining wound seal.In addition, there is loss of large volumes of extracellular fluid.2. Mesh like Vicryl and Dexon made of absorbable material can be directly applied over bowel, but the drawbacks are loss of strength in the presence of infection and higher incidence of ventral hernia development.3. Non absorbable mesh like GORE-TEX and polypropylene can be used for closure with or without zipper.These materials have good tensile strength and provide additional option of repeated surgeries.The disadvantage, however, is mesh erosion into the bowel wall forming fistula and subsequent high risk of mesh infection.
Infected wounds are opened, explored, drained, irrigated, débrided and dressed open.If fascial disruption is suspected, drainage should be performed in the operating room.The severity of the infection determines the need for antibiotic therapy.Once the infection has cleared and granulation tissue is apparent, the wound can be closed secondarily.
Fascial disruption is due to abdominal wall tension overcoming tissue or suture strength, or knot security.It can occur early or late in the postoperative period.With early fascial dehiscence, the skin closure may be intact depending upon the method of closure (ie, staples, sutures); the patient, nevertheless, is at risk for evisceration.Early postoperative fascial dehiscence is a surgical emergency.The late complication of fascial disruption is incisional hernia which can lead to bowel obstruction, ischemia and even death.
Management of the deep incisional surgical site and organ/space surgical site infection includes open abdomen technique using various types of dressings and mesh.Occasionally, single stage closure of the abdomen is used.
Of late, V.A.C dressings are the preferred choice for open abdomen management.However, the most recent development is the MIST therapy using low frequency ultrasound.

Image 1 .Image 3 .
Superficial incisional surgical site infection showing skin and subcutaneous fat involvement.Image 2. Deep incisional surgical site infection involving rectus sheath and preperitoneal space.Organ surgical site infection shown as an open abdomen with Involvement of the peritoneal cavity and omentum managed by mesh placement.Diagnosis of surgical site infection is largely clinical.

Table 1 .
4atient Related Risk Factors for Surgical Site Infection4

Table 2 .
4echnique Related Risk Factors For Surgical Site Infection4

associated with increased risk of fascial disruption 5 (Table 3 )
: Multiple factors can increase the changes of loss of integrity of the fascia and largely relate to patient factors including patients' premorbid and associated medical conditions as does patient demographics.

Table 3 .
Factors associated with increased risk of fascial disruption

Table 4 .
Wound Classification and Risk for Surgical Site Infection

practices for preventing surgical site infections 7 :
It includes ensuring adequate control of diabetes and assessment and correction of cardiovascular problems pre-operatively.-Studies have shown that cessation of smoking at least a week prior to surgery reduces the risk of SSI.-Both reduction of weight in obese patients and improvement of nutrition in cachectic patients have shown to favourably improve surgical outcome. Optimising surgical techniques at various levels starting with adequate patient preparation for surgery which include antibacterial shower on the day of surgery, shaving of the site on table.-Adequate antimicrobial prophylaxis which is continued intra operatively at 4 hourly intervals.-Mass closure of the abdominal wound incorporating all layers of the rectus sheath taking wide tissue bites of more than 1cm and with short stitch interval (less than 1cm) using suture length to wound length ratio of 4 to 1.  Reducing tissue trauma during surgery by gentle dissection of tissue, cautious use of electrocautery and saline wash-out of the wound has shown a lower incidence of SSI.Reducing operative time and appropriate use of intrabdominal drains also reduces the risk. Best