PICO is a revolutionary, canister-free, single-use, negative pressure wound therapy (NPWT) system, proven to significantly reduce post-operative complications*.
There is a specific population of patients that have an increased risk of suffering from delayed wound healing post-operatively and developing a surgical site infection (SSI). Patients in this ‘high risk’ population have at least one of the following risk factors: body mass index (BMI) ≥ 30, ASA ≥ 2, diabetes, age, smoking status, length of surgery and emergency surgery, to only name a few. Depending on the surgical field, one or more of the defined risk factors have been shown to be significant independent predictors of SSI.
BMI: Results from the 2015 Health Survey for England showed that 62.9% of adults were overweight or obese (67.8% of men and 58.1% of women). A substantial proportion of obese adults have a body mass index (BMI) of well over 30. A high BMI (>30) has been shown to be a significant risk factor for SSI. In some surgical specialties the likelihood of developing an SSI is four times higher with a BMI over 35 (compared to a BMI of 18.5). This may be due to the standard dose of prophylactic antibiotics achieving inadequate tissue concentrations or as a result of the relatively poor perfusion of adipose tissue, which may impair wound healing and decrease the local immune response, therefore facilitating the establishment of an infection.
ASA score: Patients with an ASA score ≥ 3 have been shown to have an increased risk of developing a wound complication. Recent data shows the proportion of patients with an ASA ≥ 3 for e.g. hip replacement was 22.8%; knee replacement was 21.2% and large bowel surgery was 39.9%.
Diabetes: Since 1996, the number of people diagnosed with diabetes in the UK has more than doubled from 1.4 million to almost 3.5 million. Individuals with diabetes have an increased risk of developing an SSI or wound complication with one study showing diabetes being associated with a 39.4% SSI rate. This may be due to the altered defence mechanisms, including the effects of hyperglycaemia.
The treatment of an SSI is likely to lead to additional costs to the healthcare provider as a result of longer hospital lengths of stay, increased resources for patient care, readmissions, additional surgical procedures, etc. It was demonstrated in one NHS hospital within the UK, the median additional length of hospital stay due to SSI was 10 days, and a total of 4,694 bed-days were lost over a two year period. The median additional cost attributable to SSI was £5,239 with a total cost of £2,491,424 over the study period.
The true cost of post-operative SSIs is often underestimated. However, since most of the available information is limited to inhospital and readmissions only, the incidence of SSI in the community following discharge from hospital is largely unknown.
Wound complications, of which SSIs are one aspect, can have a severe impact on patients’ quality of life and well-being and also significantly increase the risk of postoperative mortality. Urgent changes in practice are required in order to reduce the occurrence of wound complications and the burden they pose on a hospital Trust. As part of a risk stratification strategy, institutions across the country are using an active interventional therapy on the incision site of high risk patients to reduce wound complications and thus achieve better outcomes. This active therapy has a diverse mode of action and several positive outcomes can be achieved, which include helping the reduction in healing failures that lead to infection and/or dehiscence.
Traditionally, negative pressure was used to treat chronic, open, static wounds with an aim of managing wound fluid and preventing wound deterioration, in order to consequently achieve wound closure, reduce the frequency of dressing changes, improve patient mobility and quality of life and reduce overall costs. More recently, negative pressure wound therapy (NPWT) has been used prophylactically on closed surgical incisions as a method of producing predictable outcomes in terms of wound healing and reducing the prevalence of post-operative wound complications, for example seroma and haematoma formation, dehiscence, and SSI.
Evidence supports the hypothesis that the main mechanisms of incisional NPWT are:
1) Reduction of lateral tension. Depending on the amount of tissue removed or the environment, the lateral tension on an incision can be very substantial. Incisional NPWT provides support to the closed incision to reduce lateral tension (a reduction of 69.5% on an individual suture), increase tensile strength (55% more force required to separate tissues at the incision), and flattening of the incision which helps to bring the edges together. When comparing incisional NPWT to a standard dressing treatment, a 31% reduction in wound dehiscence has been observed. This may be due to the reduction in tension on the incision.
2) Reduction of haematoma or seroma. Incisional NPWT has the potential to reduce seroma formation by compressing the tissue and reducing the fascial space. This encourages fluid back into the lymphatic system and venous system, therefore not only preventing the seroma from forming but also managing any fluid which may leak out of the wound. Recent evidence has shown a significant reduction (52%) in the risk of developing a seroma with incisional NPWT compared to standard care.
3) Increased perfusion. The removal of fluid is an important mechanism by which NPWT relieves the compressive effect of extracellular fluid on surrounding tissues, the reduction in extracellular fluid leads to a decrease in capillary compression and an increase in tissue perfusion which can improve wound healing.
4) The acceleration of the elimination of tissue oedema. In a review of NPWT for the management of closed surgical incisions, it was highlighted that the reduction of tissue oedema has significance and treatment of a wider area than just the immediate incision may be desirable.
5) Protection of the incision from external contamination. The use of NPWT on closed incisions can have a substantial clinical impact. It is well documented that its use prophylactically can significantly reduce the rate of surgical site infections in many surgical disciplines, reduce the incidence of wound dehiscence and improve scar outcomes, when compared to standard care.
Recent guidelines from the World Health Organisation (2016) on the prevention of surgical site infection recommend the use of prophylactic NPWT in adult patients on primarily closed surgical incisions in high-risk wounds, for the purpose of the prevention of SSI, while taking resources into account.
Hospitals can achieve equally meaningful outcomes by proactively identifying high risk patients and procedures. The targeted use of PICO NPWT prophylactically to manage closed surgical incisions on high risk patients could help to reduce the number of wound complications including SSI. Coupled with tailored educational support and protocols, PICO NPWT could lead to a reduction in the length of hospital stay, a reduction in the number of readmissions/return to theatre rate and a reduction in outpatient clinic appointments.
PICO NPWT, by design, is discrete and utilises unique dressing technology to ensure NPWT is delivered effectively, consistently and continuously to the suture line for a period of seven days post-operatively. Wound fluid is managed via a highly breathable top film (80% fluid is evaporated and 20% held in the absorbent core) within the dressing. This eliminates the need for a canister and makes the pump light and portable. The system consists of a single-use lightweight pump which is connected to a revolutionary dressing, which provides a continuous negative pressure of -80mmHg and is disposable after seven days use. With these attributes, the PICO system is well placed to deliver NPWT in both the hospital and homecare setting and may improve patient mobility and possibly quality of life and wellbeing.
Case scenarios
Orthopaedics: A large, single-centre randomised controlled trial (RCT) in 220 patients undergoing hip or knee replacement surgery demonstrated that postoperative wound management with PICO NPWT was associated with a reduction in wound exudate and surgical wound complications. Only four per cent of the PICO NPWT treated patients had level four exudate compared to 16% of the comparator group. PICO NPWT reduced the frequency of wound complications over four fold although this was not significant (p=0.06). Further statistical analysis identified that PICO NPWT was particularly beneficial in patients with an ASA score ≥3 and BMI ≥35 (p=0.02). The PICO system was shown to reduce length of stay by 5.91 days for ASA ≥ 3 and by 6.1 days for those with a BMI ≥ 35.
Evaluation of the cost-effectiveness of incisional NPWT in the above RCT showed the cost per patient was £5,602 and £6,713 for NPWT and standard care respectively, resulting in a cost-saving of £1,132 per patient in favour of the PICO system. Further savings were observed when subgroups of high-risk patients with BMI ≥ 35 and ASA ≥ 3 were analysed (£7,955 and £7,248 per patient respectively). This suggests that the prophylactic use of the PICO system on patients undergoing primary hip or knee replacement can be considered a cost-effective and cost saving intervention to reduce surgical site complications, when compared to standard care.
Obstetrics: An observational audit study from a single NHS hospital in England introduced the PICO system (an example of a PICO NPWT pathway is shown in figure 1), as part of a package of measures, to reduce wound infection and readmission following C-section. The device was left in situ for one week as per the manufacturer’s instructions in 50 patients following C-section who had a BMI in the range of 35-53. In uncomplicated, low-risk cases (BMI <35), a conventional dressing was used (n=610). The infection rate in the patients at high risk of surgical site complications that used the PICO system was 0% compared with 6.3% in the lower risk cohort.
*Compared to standard dressings.
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References:
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49 Data on file: Reference OR-DOF/012 – A prospective open, non-comparative, multi-centre study to evaluate the functionality and dressing performance of a new negative pressure enhanced dressing in acute wounds. Hussein Dharma, March 2011.
50 Data on file: Reference DS/11/037/R2 – In-vitro wound model testing of PICO™ at a moderate exudate flow rate; Sarah Roberts, March 2011 (in-vitro).
51 Data on file: Report reference DAL-055-10-0067 – Software End of Life Timing Analysis.
