Introduction

More than 300 delegates and 36 speakers, representing Europe, America, the Middle East, Canada, Africa, Asia and Australia, convened in Berlin, Germany, in March 2015 for Smith & Nephew’s 6th International Negative Pressure Wound Therapy (NPWT) Expert Meeting. This meeting report focuses on the general surgery workstream discussed at the meeting.

The main advantages of negative pressure-assisted wound closure include partially preventing fascial and wound margins retraction, protecting peritoneal content, and allowing fluid drainage, among others. Standardised classification is needed in order to compare the relative efficacy of NPWT devices in different open abdomen conditions.

Importantly, surgical-site infections (SSIs) are more frequent than is generally reported. Indeed, at 20%, colorectal surgery has among the highest rates of SSI of all elective surgery.¹ In an attempt to reduce infection rates, Dr Gregory Sergeant recommended the postoperative use of NPWT in severely contaminated or dirty wounds. Preventive strategies to reduce SSIs should also be implemented, for instance the use of World Health Organization (WHO) surgical safety checklist.

Professor Judith Tanner conducted her own study investigating SSI rates and found a much higher SSI incidence than the Health Protection Agency (HPA) surveillance revealed. Such underreporting leads to those with robust surveillance being penalised and means staff are not as aware as they should be, leading to the problem being underprioritised.

In an effort to determine whether using the NPWT PICO^◊ would reduce SSI rates, Dr Pauline Whitehouse used PICO^◊ after surgery and found that SSI rates were reduced. NPWT should be considered when planning a perioperative pathway to reduce SSIs, but careful consideration would need to be given to which patients would most benefit. NPWT is the key technique for an individualised approach to wound care, but only in experienced hands.

Open abdomen surgery: Intra-abdominal infections in the open abdomen and the role of NPWT

Chair: Professor Michael Sugrue

Dr Stefano Rausei spoke about intra-abdominal infections in the open abdomen and the role of NPWT. He suggested that there is a shortage of high-level evidence to support NPWT’s use in managing the open abdomen and asked: ‘should we really wait for the evidence?’ Dr Rausei’s answer was ‘No’, via a quote from Schein’s Common sense emergency abdominal surgery: ‘when high-level evidence is not available, we have to use an individual approach and common sense.’

Referring to his own study,² Dr Rausei said that, despite the obvious lack of strongly supported evidence, negative pressure-assisted closure (VAC^TM) techniques seem to be superior and are widely adopted by surgeons. The more commonly accepted advantages of negative pressure-assisted closures for septic peritonitis open abdomen management include:
• It makes surgical re-look easy
• Partially preventing fascial and wound margins retraction
• Protecting peritoneal content
• Allowing peritoneal fluid drainage and computation
• Identifying early enteric leakage
• Preventing intra-abdominal hypertension.

Open abdomen surgery: Use of NPWT in open abdomen – discussion of existing guidelines

Professor Andreas Bruhin presented a systematic review and evidence-based recommendations for NPWT’s use in open abdomen surgery.³ Classification is vital in deciding patient management and Professor Bruhin listed different forms that work for some conditions, but not for the open abdomen. It is crucial to have a common classification language so everyone is comparing like with like (not ‘apples with bananas’).

His favoured study⁴ has four grades with condition descriptions ranging from Grade 1A: clean open abdomen without any adherences and beginning lateralisation of the abdominal wall; 1B: the same as Grade 1A, but contaminated; to 4: frozen open abdomen, unable to close surgically, with or without fistula. Evidence level, adapted from the Scottish Intercollegiate Guidelines Network classification method, ranges from 1++: high-quality meta-analyses, systematic reviews of randomised controlled trials (RCTs) or RCTs with a very low risk of bias, to 4: expert opinion. These translate into Recommendation Grades that range from A: mandatory, to D: possible, or GPP: good practice point.

With the grading, you can compare the relative efficacy of the device methods (NPWT Kit, NPWT Kit and sequential closure, VAC^TM – pack, artificial burr, Bogota bag) with different open abdomen conditions: septic/non septic/mixed, with patients (studies), fascial closure, mortality and fistula rates. Treatment goals are protection, management and closure, which are each defined by grade with recommended treatments for different patient conditions and levels of severity.

To choose the right treatment for the open abdomen, it is important to understand anatomy: the gliding areas between the bowel and the abdominal wall, and a kind of gliding area between the fascia and the subcutis and the cutis.

NPWT is the key technique for an individualised approach, but only in experienced hands. ‘It’s not a place to try, you have to learn how to work with it: provide different actions at different stages: wound and fluid management, facilitating primary fascial closure, splinting skin grafts and avoiding production of enteroatmospheric fistula formations’, he concluded.

Open abdomen surgery: Open abdomen with NPWT and mesh-mediated fascial traction

Dr Thordur Bjarnason explained his background as a surgeon and talked about his PhD thesis on open abdomen therapy using negative pressure and mesh-mediated fascial traction. Open abdomen therapy may be used for assorted urgent conditions. Possible complications to open abdomen therapy include enteric fistulas caused by damage to the exposed bowel, and the inability to close the abdomen, resulting in large ventral hernias.

Having a reliable temporary abdominal closure is vital, but which one? The Bogota bag has no room for expansion when stretched and no way of removing toxic fluid. Zippers designed for temporary closures are impermeable and have no barrier to prevent adhesions to the abdominal wall.

American studies showing promising results with NPWT alone used relatively young trauma patients, while those for Dr Bjarnason’s study⁵ were mainly elderly and non-trauma, needing prolonged open abdomen therapy. He and his co-authors developed a modified method combining NPWT and traction: vacuum-assisted wound closure and mesh-mediated fascial traction (VAWCM), in a bid to improve delayed primary fascial closure without increasing complication risks (Figure 1).

They treated 111 consecutive patients with a median age of 68, mainly non-trauma, at four Swedish hospitals. Sixteen patients died with open abdomen, a further 17 died from multiple organ failure or sepsis in hospital after the open abdomen was closed. Overall mortality was 30%.

Eighty-five patients had a delayed primary fascial closure with removal of the mesh and closure of the fascia. VAWCM provided a high closure rate, 89% with primary closure and 9% with mesh closure, whereas 2% had incomplete fascial closure with complete skin closure. There were six (5%) permanent enteroatmospheric fistula (EAF), in line with other studies, therefore no more with this method. Five of those patients had previously been treated for bowel ischaemia and all six, very ill patients, sadly died.

Sixty-four patients were alive after one year and none were lost to follow-up. Incisional hernia incidence was high, but most hernias were small and asymptomatic (diagnosed by CT scan) and few needed surgery during the first year.

He concluded with a list of practical tips and the offer of a free download of his thesis⁶ from Lund University at: www.lu.se/lup/publication/4221708

Open abdomen surgery: Open abdomen and concomitant entero-atmospheric fistula: proposal of a clinical algorithm

Dr Salomone Di Saverio talked about the open abdomen and concomitant EAF, together with his proposed clinical algorithm: his ‘attempt to rationalise the approach to a surgical nightmare’.

He began by defining the EAF as an enteric fistula that occurs in the middle of an open abdomen. It usually arises in the midst of a granulating ‘frozen’ abdomen, making spontaneous closure or sealing almost impossible.

Mortality has fallen from 70% in past decades to 42% currently. The causes of EAF are multiple, usually as a consequence, for instance, of anastomotic disrupture, adhesions and severe wound infections, visceral trauma during dressing changes or bowel ischemia.

Many studies have been published on management options for EAF, causing much confusion, so there needs to be a rationalisation, said Dr Di Saverio. His paper,⁷ based on his clinical experience when faced with a patient with high-output fistula, proposes an algorithm to steer the surgeon through separate routes for the different types of EAF.

Colorectal surgery: Incidence of surgical site infection after colorectal surgery

Chair: Professor Michael Sugrue

Dr Gregory Sergeant focused on the incidence of SSI after colorectal surgery, with the aim of demonstrating that SSIs are more frequent than is generally reported and suggesting some preventive strategies.

There is around a 20% incidence of SSI after colorectal surgery,¹ which is among the highest rates of infection of all elective surgery. The increased use of laparoscopic surgery has contributed to the underestimation of SSI incidence, said Dr Sergeant, but enhanced recovery after surgery strategies that lead to earlier discharge mean that many SSIs are increasingly diagnosed post-discharge. One study⁸ showed the average time until SSI diagnosis is seven days in hospital and 14 days post-discharge.

It is unsurprising that colorectal surgery has a higher SSI rate than other areas with its very high levels of bacteria, and emergency procedures such as purulent peritonitis and bowel perforations, that lead to extremely high wound infections. Other important factors are virulence and the increasing resistance to antibiotics in a patient population that is getting older and has more comorbidities.

Careful attention to diagnosis is crucial: check the wounds, open the dressings – look at the colour of the wound, the discharge and smell, and attend to any small fever, which might indicate a wound infection.

Dr Sergeant divides risk factors into four: patient, pathology, treatment and environment. The patient is the most important (75% by his estimation): advanced age, ASA score <2, obesity, malnutrition, diabetes, anaemia, shock, etc. Many studies have shown the value of antimicrobial prophylaxis,^9,10 which must be given within one hour before skin incision and discontinued after 24 hours.

Dr Sergeant’s recommended intra-operative prevention: use (dual ring) wound protectors, irrigate the wound as standard practice, hyperoxia, maintain normothermia – all Level 1 evidence.^11–14 Control glucose level, reduce unnecessary traffic in operating rooms, adhere to hand hygiene and change gloves regularly. Postoperatively, consider the use of NPWT in severely contaminated or dirty wounds.

Preventive strategies ideally are part of clinical pathways, a combination of measures that together can lead to a reduction in SSI, for instance the preventive SSI bundle and the use of the WHO surgical safety checklist that led to reduced surgical complications, including SSI.^15,16 Hospitals should perform surveillance for SSI, and feedback SSI rates to perioperative personnel and management.

Dr Sergeant concluded that preventive strategies could dramatically decrease the high incidence of superficial SSI in (open) colorectal surgery.

Postoperatively, consider the use of NPWT in severely contaminated or dirty wounds…preventative strategies could dramatically decrease the high incidence of superficial SSI in (open) colorectal surgery.
Dr Gregory Sergeant

Colorectal surgery: Post-discharge surveillance to identify colorectal surgical site infection rates and related costs

Professor Judith Tanner talked about her study of post-discharge surveillance designed to identify colorectal SSI rates and related costs. Professor Tanner was unconvinced about the accuracy of the HPA surveillance information on colorectal SSI rates and she sought to establish surveillance information for her hospital in Nottingham.

For four months, a surveillance nurse collected data on every patient undergoing colorectal surgery, using the HPA and Centers for Disease Control (CDC) and Prevention SSI definition. She telephoned, spoke to, or visited every patient on days 10, 20 and 30 to ask about their wounds, and if patients had received antibiotics she asked the GP whether they had examined the wound or just prescribed.

The HPA national SSI rate was 10%. Professor Tanner’s study revealed a 27% rate among the 105 patients in the hospital under surveillance. The total cost of treating 29 patients for four months: £300 616; the one-year projection of total cost: £915 519.

However, indirect costs are rarely studied. A German study showed one patient’s hospital stay prolonged by an SSI prevented 33 new admissions, plus the loss to society of earnings and productivity, and sickness benefit.

A literature review of other active gold-standard surveillance of colorectal SSI rates^17–21 revealed much higher SSI rates than those of the HPA. The UK’s SSI rates are used for identifying outliers, benchmarking league tables, financial penalties, commissioning and public profile. It is not in respondents’ interest to reveal their true infection rates.

Professor Tanner spoke of her contact with a patient about his deep wound infection. He had been readmitted to the hospital, returned to theatre and had three cycles of antibiotic treatment, yet was unaware his wound had been infected. ‘And he was not alone. Some think it’s normal to be on an intravenous drip after surgery,’ she said.

In 2012 Professor Tanner organised a national audit of SSI definitions and data collection methods used by hospital Trusts in England (106 of 156 Trusts responded). The only mandatory HPA information is on joint replacement for three months of the year. The audit found that 67 of the 106 trusts were voluntarily following up in-patient, readmission and post discharge, and their data were much better than the mandatory data.

Professor Tanner concluded that the HPA’s national surveillance programme in England is not adequate for benchmarking because data collection methods are not standardised: 10% of Trusts sent in-patient only data, 10% did not report superficial SSI data and 10% did not use the HPA SSI definition.

Under-reported data mean that hospitals (or surgeons) with robust surveillance are penalised, either financially or reputationally. SSIs are massively underestimated, which leaves staff and patients unaware, the problem underprioritised and costs underestimated.

The survey’s publication caused a big media stir briefly, but long-term impact has been very small, and Professor Tanner concluded: ‘we need to have proper surveillance, to identify the true rate and the true cost of infections.’

The HPA’s national surveillance programme in England is not adequate for benchmarking because data collection methods are not standardised…we need to have proper surveillance, to identify the true rate and the true cost of infections.
Professor Judith Tanner

Colorectal surgery: Mode of action of NPWT on a closed incision

Dr Elizabeth Huddleston talked about the modes of action of NPWT on a closed incision, and whether they are applicable or relevant to colorectal surgery. There has been a paradigm shift in the way NPWT is used since the expert meetings began five years ago, said Dr Huddleston: from treatment to prevention, where negative pressure is applied to a closed incision with the intention of reducing the frequency of post-surgical infections.

There is growing recognition of incisional NPWT’s (iNPWT) value in minimising tension on a closed wound and giving better apposition of the incision. There are probably multiple mechanisms of action with different benefits for different wounds, but we need to understand NPWT’s mode of action, and the evidence so far is scarce.

Dr Huddleston described a biomechanical analysis of the change in forces when NPWT (Prevena^TM) is applied to incisions. It is believed that negative pressure relieves the lateral tensions created by applying sutures on an incision.²²

In an experimental study in pigs, an incision was treated for three days, in one group with NPWT and with standard dressings in another group. The tissue was then harvested and the force needed to pull apart the wounds was measured. The NPWT-treated wounds needed a much higher pressure to separate the sides.²³

Other experimental studies found evidence that significantly less haematoma/seroma was formed when iNPWT was used and suggest that iNPWT enhances lymphatic drainage of subcutaneous fluids.²⁴

However, there is still much to learn about NPWT’s effects on oedema and blood flow^25,26 and evidence about NPWT’s effects on wound bacterial levels is contradictory. There are still gaps in our understanding of its mechanism of action, and the scientific community needs more prospective RCTs and fewer retrospectives to address some of the conflicting evidence.

The NPWT-treated wounds needed a much higher pressure to separate the sides.^₂₃ Other experimental studies found evidence that significantly less haematoma/seroma was formed when iNPWT was used and suggest that iNPWT enhances lymphatic drainage of subcutaneous fluids.²⁴
Dr Elizabeth Huddleston

Colorectal surgery: Prophylactic use of PICO◊ NPWT to reduce surgical site infections following large bowel surgery

Dr Pauline Whitehouse presented the results of a small study she had been conducting with PICO^◊ for closed laparotomy incisions at Worthing hospital.²⁷ She talked about the hurdles to implement her plan to use PICO^◊, because of an NHS funding crisis. As Professor Tanner suggested earlier in the meeting, the HPA figure of 10% incidences of large bowel SSI were a long way from the 20–30% in her hospital and 23% after laparotomy.

She wanted to add PICO^◊ to try and prevent infections in her hospital so she made a business case proposing a 50% reduction in SSIs due to PICO^◊ protocol. Inclusion criteria specified one or more SSI risk factors: age >70, body mass index >35, emergency operation or diabetes/immunosuppression. But it was left to the consultant to decide whether or not to use PICO^◊. Wound closure was as usual: sutures or staples, but no skin glue.

Nurses and surgeons needed training in the workings of PICO^◊: nurses asked for the battery to be changed, not having understood that it stopped working after seven days.

Worthing Hospital, using PICO^◊ from May to November 2014, met its 50% SSI reduction rate: using infection rates from the same period in 2013, they would have expected eight patients with SSIs, but there were only two. The Trust’s other hospital, not using PICO^◊, also reduced its infection rate, but it did not reach statistical significance.

The infection rate increased in the following quarter when the hospital refused to allow continued PICO◊ use before presentation of the data, so for three months only 10% of patients could be treated with left-over supplies.

In 2013, the SSI rate was 7.69% in nine patients, leading to a cost of £90 000. The projected financial impact for 2014, assuming no change in the SSI rate in 102 patients and assuming PICO^◊ use in all laparotomies, suggests a potential saving of £45 760.

These are early data and patient numbers are small. It is difficult to access documentation and the choice about whether to use PICO^◊ was left to the consultant. The Executive Board are very keen to extend the use of PICO^◊ across both hospitals for different specialities, and her main aim in the next few months is to increase the use of PICO^◊ for high-risk, elective and emergency laparotomy patients and to roll it out for other specialities.

Colorectal surgery: Use of PICO◊ single-use NPWT to prevent post-surgical wound complications in Crohn’s disease patients: available evidence and analysis of age-related factors

Dr Gianluca Pellino examined the use of PICO^◊ in preventing SSIs in general and colorectal surgery, with particular focus on age-related factors.

The American College of Surgeons (ACS) developed an ‘intervention bundle’²⁸ that aimed to halve the SSI rate by reviewing the literature then enhancing processes and establishing infrastructure. After applying the protocols, they found there was a significant reduction in superficial SSIs, but not in deep organ space SSI.

There was no suggestion of NPWT as a prophylactic measure in the ACS report, leading Dr Pellino to suggest to the journal that it should be considered when planning a perioperative pathway to reduce SSIs, at least with selected patients. The question was how to select patients who would benefit from that approach.³⁰

A literature review for evidence about colorectal surgery and SSI found only five eligible papers,³¹ so he set up a pilot trial to test the effects of PICO^◊ on surgical wounds of patients with a risk factor. He chose 30 patients who had been operated on for Crohn’s disease and split them into two groups: 13 in the PICO^◊ NPWT group and 17 in the conventional dressing group.

Results showed that NPWT as a prophylactic measure significantly reduced seroma and SSI (classified with CDC criteria). They extended the trial and included 50 patients, performed a logistic regression to identify independent predictors of SSI, and found that corticosteroids doubled the risk of SSI, independently of age, and that PICO^◊ helped prevent the complication.

Their next step was to assess the safe use of NPWT with frail, elderly patients and compare its effectiveness with younger patients.³² They split 100 patients into those undergoing breast or colorectal disease, with 10 patients aged over 65 in each group to allow sub-analyses. Each group of 25 patients received either PICO^◊ NPWT or conventional dressings.

Results showed that PICO^◊ significantly reduced SSI in both breast and colorectal groups compared with controls. They saw no significant difference related to age. In colorectal patients, according to these data, iNPWT is superior to conventional dressings in reducing SSI with evidence level EL2b.

Age in itself should not be regarded as a risk factor, but should be balanced with other comorbidities when selecting for NPWT. The report concluded that NPWT, where used appropriately, is safe as a prophylactic measure and can reduce hospital length of stay by reducing the incidence and impact of SSI in patients undergoing general surgery and colorectal surgery specifically.

NPWT is safe as a prophylactic and can reduce hospital length of stay by reducing the incidence and impact of SSI in patients undergoing general surgery and colorectal surgery specifically.
Dr Gianluca Pellino

Colorectal surgery: Combined use of antimicrobials and NPWT for high-risk colorectal incisions

Dr Sebastian Smolarek presented the interim results of a multicentre prospective RCT to assess the role of NPWT (PICO^◊) combined with an antimicrobial dressing (ACTICOAT^◊) on closed incisions in colorectal and high-risk patients against standard care.

ACTICOAT^◊ has a well-established role in treating burns,^33,34 and has been shown to significantly reduce the bacterial count in a clinical setting.^35,36 So in theory, there is a possibility of creating an almost ideal dressing by connecting an antimicrobial dressing, in this case ACTICOAT^◊, with the benefits of negative pressure to give a good seal, a good influence on the wound bed, as well as an antimicrobial.

The primary outcome is a reduction of 50% in the wound infection rate (using CDC criteria). Secondary outcomes are to reduce length of stay, decrease antibiotic use for wound infection and cut patient treatment costs. Preliminary results show 30% of patients across both groups developed an SSI. There was no significant difference between the two groups and length of stay was the same.

Dr Smolarek noted that it is too early to draw a conclusion about the study. Approximately 75% of the SSIs in the PICO^◊ group were observed in patients with stoma. This is the biggest risk factor for SSIs in this study. There is a need for good communication between the stoma nurse and the medical team when NPWT is planned, and preoperative stoma marks should be placed more laterally than normal to leave room for a good seal for PICO^◊.

Dr Smolarek drew attention to the importance of careful marking on a stoma to leave room for a good seal for the dressing on the edge of the PICO^◊.

Conclusions

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