Sternal Wound Infection and Vacuum-Assisted Closure
Sternal Wound Infection and Vacuum-Assisted Closure
Introduction. Previous work has demonstrated the efficacy of vacuum-assisted closure (VAC) in the treatment of poststernotomy local wound infections, compared to historical treatment protocol. The negative pressure has been found to protect wounds against contamination, prevent wound fluid retention, increase blood flow, and increase rates of granulation tissue formation. For this study, a retrospective analysis compared patients receiving VAC as definitive treatment versus bridging to delayed flap closure.
Methods. Sixteen patients developed sternal wound infections after cardiac surgeries at the authors' institution from 2006 to 2008. Data was gathered regarding patient comorbidities, treatment method, and outcome. Study objectives included assessment of risk factors that warranted secondary surgical closure and examination of long-term followup where VAC was the definitive treatment modality.
Results. Group A (n = 12) had VAC as the final treatment modality. Group B (n = 4) required myocutaneous flap closure. One patient in Group B passed away prior to flap surgery. Both groups had similar risk factors, except Group B had a higher risk of body mass index (BMI) > 35 that was near statistically significant (P = 0.085; odds ratio = 0.0, 95% CI = [0.0 – 1.21]). Group A required a shorter hospital stay on average. Long-term follow-up showed the majority of Group A had completely healed sternal wounds 2-3 years from initial cardiac surgery.
Conclusions. Vacuum-assisted closure as definitive treatment modality is a successful, first line therapy for local superficial sternal wound infections. When deep infections occur, however, VAC as bridge-to-flap coverage is recommended over attempted secondary healing with VAC.
Sternal wound infections after cardiac surgery is a concerning complication, increasing morbidity and mortality. Approximately 0.3% - 5.0% of median sternotomy surgical approaches result in infection. Mortality rates range in the literature between 14% - 47%. Preoperative risk factors for sternal wound infections include diabetes mellitus, chronic obstructive airway disease, obesity, and smoking. Postoperative risk factors include blood transfusions, surgical chest exploration, prolonged postoperative ventilation, and longer stay in the intensive care unit.
Microbiology of sternal wound infections is variable. Staphylococcus aureus is the most common pathogen (29%), followed by Staphylococcus epidermidis (22%), with a notable frequency of Pseudomonas aeruginosa, methicillin-resistant staphylococci and streptococci, facultative and aerobic gram-negative rods, and anaerobes.
Since the mid-1950s, when the median sternotomy became a common approach for intracardiac procedures, the poststernotomy wound infection has had few treatment solutions. Superficial infections were treated by irrigation, debridement, and open dressing changes. Deep infections were more difficult to treat. One of the first treatment options for deep sternal wound infections was a closed mediastinal antibiotic irrigation system. This was an improvement from prior treatment regimen of open wound healing, following initial debridement, with frequent dressing changes to promote granulation and secondary wound closure. Later treatment options involved debridement of devitalized tissue, daily dressing changes, and eventual delayed definitive closure of the wound by vascularized flaps such as pectoralis muscle, rectus muscle, or omental transpositions.
In the 1990s, the advent of negative pressure devices improved management of pressure ulcers and chronic wounds. Since then, vacuum-assisted closure (VAC) devices have revolutionized wound management, improving skin grafts, enhancing reepithelialization of skin graft donor sites, and allowing safe temporary closure of the abdomen. Negative pressure devices improve tissue healing through several proposed mechanisms, including an increase in local blood flow, reduction in tissue edema, removal of chronic wound fluid and necrotic tissue, reduction in bacterial colonization rates, and wound size contraction.
Vacuum-assisted closure consists of a vacuum pump, polyurethane foam into which an evacuation tube is embedded, and a transparent adhesive dressing (KCI International, San Antonio, TX). The reticulated polyurethane foam has a 400 μm - 600 μm pore size. The foam is cut and contoured to fit the size of the tissue defect. The foam is covered with an adhesive drape and connected through the evacuation tube to the vacuum pump. The suction generates a continuous vacuum, equally distributed in the foam. The negative pressure ranges from 0 - 200 mm Hg with typical therapeutic range from 75 mm Hg - 125 mm Hg. The foam is changed every 2–3 days.
Nevertheless, the literature lacks a large prospective multicenter trial. Long-term outcome, in general, is lacking. Questions remain regarding sternal stability and need for further treatment. In an attempt to improve upon the existing methods, this study aimed to evaluate VAC as an effective short-term treatment and durable long-term treatment for sternal wound infections. Furthermore, this study sought to investigate the utilization of VAC to lessen the need for further invasive treatment options, such as myocutaneous and/or omental flap coverage. The authors expected patients who responded to VAC as definitive treatment to have fewer co-morbid risk factors than patients who required secondary surgical closure. In addition, the authors proposed that the VAC technique as definitive treatment would reduce treatment time, hospital stays, and outpatient followup. Finally, the authors expected long-term followup to show complete healing with VAC as definitive closure, as well as high patient satisfaction.
Abstract and Introduction
Abstract:
Introduction. Previous work has demonstrated the efficacy of vacuum-assisted closure (VAC) in the treatment of poststernotomy local wound infections, compared to historical treatment protocol. The negative pressure has been found to protect wounds against contamination, prevent wound fluid retention, increase blood flow, and increase rates of granulation tissue formation. For this study, a retrospective analysis compared patients receiving VAC as definitive treatment versus bridging to delayed flap closure.
Methods. Sixteen patients developed sternal wound infections after cardiac surgeries at the authors' institution from 2006 to 2008. Data was gathered regarding patient comorbidities, treatment method, and outcome. Study objectives included assessment of risk factors that warranted secondary surgical closure and examination of long-term followup where VAC was the definitive treatment modality.
Results. Group A (n = 12) had VAC as the final treatment modality. Group B (n = 4) required myocutaneous flap closure. One patient in Group B passed away prior to flap surgery. Both groups had similar risk factors, except Group B had a higher risk of body mass index (BMI) > 35 that was near statistically significant (P = 0.085; odds ratio = 0.0, 95% CI = [0.0 – 1.21]). Group A required a shorter hospital stay on average. Long-term follow-up showed the majority of Group A had completely healed sternal wounds 2-3 years from initial cardiac surgery.
Conclusions. Vacuum-assisted closure as definitive treatment modality is a successful, first line therapy for local superficial sternal wound infections. When deep infections occur, however, VAC as bridge-to-flap coverage is recommended over attempted secondary healing with VAC.
Introduction
Sternal wound infections after cardiac surgery is a concerning complication, increasing morbidity and mortality. Approximately 0.3% - 5.0% of median sternotomy surgical approaches result in infection. Mortality rates range in the literature between 14% - 47%. Preoperative risk factors for sternal wound infections include diabetes mellitus, chronic obstructive airway disease, obesity, and smoking. Postoperative risk factors include blood transfusions, surgical chest exploration, prolonged postoperative ventilation, and longer stay in the intensive care unit.
Microbiology of sternal wound infections is variable. Staphylococcus aureus is the most common pathogen (29%), followed by Staphylococcus epidermidis (22%), with a notable frequency of Pseudomonas aeruginosa, methicillin-resistant staphylococci and streptococci, facultative and aerobic gram-negative rods, and anaerobes.
Since the mid-1950s, when the median sternotomy became a common approach for intracardiac procedures, the poststernotomy wound infection has had few treatment solutions. Superficial infections were treated by irrigation, debridement, and open dressing changes. Deep infections were more difficult to treat. One of the first treatment options for deep sternal wound infections was a closed mediastinal antibiotic irrigation system. This was an improvement from prior treatment regimen of open wound healing, following initial debridement, with frequent dressing changes to promote granulation and secondary wound closure. Later treatment options involved debridement of devitalized tissue, daily dressing changes, and eventual delayed definitive closure of the wound by vascularized flaps such as pectoralis muscle, rectus muscle, or omental transpositions.
In the 1990s, the advent of negative pressure devices improved management of pressure ulcers and chronic wounds. Since then, vacuum-assisted closure (VAC) devices have revolutionized wound management, improving skin grafts, enhancing reepithelialization of skin graft donor sites, and allowing safe temporary closure of the abdomen. Negative pressure devices improve tissue healing through several proposed mechanisms, including an increase in local blood flow, reduction in tissue edema, removal of chronic wound fluid and necrotic tissue, reduction in bacterial colonization rates, and wound size contraction.
Vacuum-assisted closure consists of a vacuum pump, polyurethane foam into which an evacuation tube is embedded, and a transparent adhesive dressing (KCI International, San Antonio, TX). The reticulated polyurethane foam has a 400 μm - 600 μm pore size. The foam is cut and contoured to fit the size of the tissue defect. The foam is covered with an adhesive drape and connected through the evacuation tube to the vacuum pump. The suction generates a continuous vacuum, equally distributed in the foam. The negative pressure ranges from 0 - 200 mm Hg with typical therapeutic range from 75 mm Hg - 125 mm Hg. The foam is changed every 2–3 days.
Nevertheless, the literature lacks a large prospective multicenter trial. Long-term outcome, in general, is lacking. Questions remain regarding sternal stability and need for further treatment. In an attempt to improve upon the existing methods, this study aimed to evaluate VAC as an effective short-term treatment and durable long-term treatment for sternal wound infections. Furthermore, this study sought to investigate the utilization of VAC to lessen the need for further invasive treatment options, such as myocutaneous and/or omental flap coverage. The authors expected patients who responded to VAC as definitive treatment to have fewer co-morbid risk factors than patients who required secondary surgical closure. In addition, the authors proposed that the VAC technique as definitive treatment would reduce treatment time, hospital stays, and outpatient followup. Finally, the authors expected long-term followup to show complete healing with VAC as definitive closure, as well as high patient satisfaction.
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