Preliminary result with incisional negative pressure wound therapy and pectoralis major muscle flap for median sternotomy wound infection in a high‐risk patient population

Introduction

Open‐heart surgery with median sternotomy access can be followed by severe complications as heart failure, stroke and sternal bone infection 1, 2. Sternal wound infection (SWI) is a complication with a great impact on costs of care and hospitalisation 3, 4.

Obesity [body mass index, (BMI) ≥ 30], diabetes, smoking, age above 66 years and female gender are all considered high‐risk factors for developing postoperative SWI 5, 6, 7.

When the infection is localised in the skin, subcutaneous tissues until the pectoralis fascia, it is called superficial sternal wound infection (SSWI) and its incidence ranges from 0·8% to 8%. When there are clinical evidences of mediastinitis (chest pain, fever, sternal instability and purulent drainage), or an organism is isolated from blood culture or from drainage of mediastinal area 8, 9, 10, there is a deep sternal wound infection (DSWI), which has a lower incidence of up to 5% 11, 12, 13, 14, 15.

‘Conventional’ therapy of DSWI provides debridement and secondary closure or closed catheter irrigation. This leads to mortality rates that range from 5% to 80% 14, 16.

In the last years, however, management of DSWI has developed considerably and mortality rates reduced to a range of 4·8–10·5% with radical debridement and closure of the defects with vascularised flaps 17, 18, 19.

Pectoralis major, rectus abdominis and latissimus dorsi muscle flaps represent the main choices for sternal wound coverage and infection control 12, 17, 18, 19, 20.

Another technique that has proven to be able to reduce the incidence of these wounds' complications is negative pressure incision management system 21. One of these systems is Prevena™ (KCI, San Antonio, TX). Its positive outcomes have been reported in the literature in decreasing wound infections' rate in obese post‐sternotomy patients 22.

In this study, we aimed to evaluate the outcome of Prevena™ Incision Management System after sternotomy and monolateral pectoralis major muscle flap (MPMF) coverage in patients with DSWI major risk factors (obesity, diabetes, smoking, age above 66 years, female gender). The study group results were compared with those achieved in a control group that underwent conventional wound dressings.

Materials and methods

Results

Discussion

The Prevena™ Incision Management System consists of a foam placed in wound's bed, connected to suction system that leads to a canister that collects aspirated fluids. This system creates a negative pressure of −125 mmHg in the wound and its dressing contains ionic silver (0·019%) that prevents bacterial growth 22.

Utility of negative wound pressure therapy has been described in complicated wounds' management 21, 22, 23, such as in DSWI 24, 25.

We strongly believe that the use of flaps together with a good debridement of the wound can be helpful in the management of DSWI.

Among the muscle flaps that can be used in these cases, MPMF is described as an effective and rapid technique. It does not depend on intact thoracic arteries that can be damaged during cardiac surgery and it leads to low postoperative morbidity and mortality 26, 27, 28, 29. In cases of DSWIs, after radical debridement, monolateral or bilateral pectoralis major muscle flap surgery represents the standard procedure at our department.

Nevertheless, in the past years, among patients with major risk factors, this technique lead to some complications even in cases where wound's closure was performed in tension‐free manner. In 23% of these cases occurred minor complications, while 15% presented major complications that required surgical revision.

In 2012, we introduced Prevena™ in our department and aimed to exploit its ability to reduce wounds tension in order to decrease complication rates in patients at risk after flap surgery for DSWI. Besides, its election was sustained by contemporary literature's description of how Prevena™ system can reduce from 16% to 4% the incidence of infections (usually sustained by gram‐positive skin flora) in obese patients 30.

The alternative method is to use conventional dressing and elastic bandages positioned in a way to reduce tension of the wound, but it has to be considered that this method can easily fail because of poor patient's compliance.

Our results evidenced Prevena™ advantages: patients who underwent this treatment had a shorter postoperative stay at the ICU (mean 1·7 versus 7·0 days) and a shorter overall stay in hospital (mean 17·3 versus 29·0 days). Moreover, revision surgery was necessary only in 3% of the study group patients, while 15% of the patients in control group needed surgical revision for postoperative wound‐related complications.

The most remarkable result was the difference between incidence of sternum dehiscence: it was observed in 15% of the control group patients and it did not occur in the study group (0%) 31, 32.

In conclusion, we observed the benefits that Prevena™ system carries in managing complicated wounds in a high‐risk patient population. The study presented some limitations: a small cohort of patients that lead to non‐significant statistical results and its retrospective character. Larger numbers of patients should be involved and long‐term results should be collected in further prospective studies.

Despite these limitations, a far lower rate of revision surgery after flap surgery, a shorter stay in the ICU and an overall shorter hospitalisation length were observed and these outcomes lead to lower economic burden to the hospital.

We could demonstrate that Prevena™ can be a useful additional tool in the treatment of high‐risked patients (obese patients BMI ≥ 30, diabetics, smokers, age ≥ 66 years and female gender) with DSWI and subsequent pectoralis major muscle surgery. Further study with a larger cohort of patients will be necessary to confirm our results.