Sternal wound infection (SWI)- 正中胸骨傷口感染

Superficial sternal wound infections (SWI) :
Confined to the skin and/or subcutaneous tissue and pectoralis fascia with overall good response to antimicrobial therapies and local wound care. 

Deep sternal wound infections (SWI) :
Sternal osteomyelitis with or without infection of the retrosternal structure

Incidence: 1-5%
Gummert J F, Barten M J, Hans C, et al. Mediastinitis and cardiac surgery—an updated risk factor analysis in 10,373 consecutive adult patients. Thorac Cardiovasc Surg. 2002;50:87–91.
high mortality (10 - 40%)
Risk factor:
 diabetes, obesity, chronic obstructive pulmonary disease, osteoporosis, tobacco use, reoperation, prolonged intensive care unit stays, and use of assist devices.
Gummert J F, Barten M J, Hans C, et al. Mediastinitis and cardiac surgery—an updated risk factor analysis in 10,373 consecutive adult patients. Thorac Cardiovasc Surg. 2002;50:87–91.
As defined by the Centers for Disease Control and Prevention, DSWIs require the presence of one of the following criteria: (1) an organism isolated from culture of mediastinal tissue or fluid; (2) evidence of mediastinitis seen during operation; or (3) presence of either chest pain, sternal instability, or fever (> 38°C), and either purulent drainage from the mediastinum, isolation of an organism present in a blood culture, or culture of the mediastinal area

IMA use, ICU / IC treatment > 5 days, postoperative ventilator time > or = 72 h, need for reexploration, diabetes, surgery time > or = 180 min, assist device implantation (including use of IABP), peripheral vascular disease and increased body mass index. Multivariate analysis identified double IMA, ICU treatment > 5 days, single IMA, diabetes, reexploration and increased body mass as significant risk factors.

Sternal infection type:
Pairolero P C, Arnold P G. Management of infected median sternotomy wounds. Ann Thorac Surg. 1986;42:1–2
 Type I infections occur within the first week after sternotomy and typically have serosanguineous drainage but no cellulitis, osteomyelitis, or costochondritis. They are typically treated with antibiotics and a single-stage operation. The majority of cases are type II infections, which occur during the second to fourth weeks after sternotomy and usually involve purulent drainage, cellulitis, and mediastinal suppuration. Costochondritis is rare, but osteomyelitis is frequent. Treatment begins with exploration and debridement of all necrotic tissues with removal of all foreign materials and exposed cartilage. Suction drains and muscle transposition are used to close the wound when the mediastinum is soft and pliable. Type III infections occur months to years after sternotomy and typically involve chronic draining sinus tracts and localized cellulitis. Although mediastinitis is rare, osteomyelitis, costochondritis, and/or retained foreign bodies are often present. These chronic wounds are packed open and treated with frequent dressing changes and repeated debridement as indicated. When the wound appears clean, it is closed with methods similar to those used in advanced type II infections.

Wound clonization:
staphylococcal strains (methicillin-sensitive Staphylococcus aureus,methicillin-resistant Staphylococcus aureus, Staphylococcus epidermidis)

Staphylococcus species: easy forming biofilm. 

Biofilm on wire:
in vitro: study

In vivo: re-do OP: non-infected vs infected wound 

Prophylactic perioperative antibiotic therapy and intranasal prophylaxis with mupirocin
No mediastinitis was observed in the MIC group.--> considered in high risk for DSWI
IMA take down: avoid pedicled take down (better skeletonized) in DM patient. 

surgical debridement, vacuum-assisted closure, rigid sternal fixation, and flap reconstruction, sternal plating.

Vacuum-assisted closure:
bacteremia, wound depth greater than 4 cm, and bony exposure and sternal instability are strong predictors of VAC failure, and definitive surgical treatment should be sought in lieu of single-therapy VAC treatment.
Complications with VAC use include a possible increased risk of bleeding and potential damage to underlying tissues, in particular the rare complication of right ventricular rupture.

ClassificatTable 2
ion base management:

Nitinol clip 的使用
the use of Nitinol clips after VAC therapy demonstrated to be a safe and non-invasive option for sternal resynthesis. After VAC therapy, a reduction in number of muscular flaps used and an increase of direct sternal resynthesis were observed.
Eur J Cardiothorac Surg. 2009 May;35(5):833-8. doi: 10.1016/j.ejcts.2008.12.036. Epub 2009 Feb 11.
Improved results of the vacuum assisted closure and Nitinol clips sternal closure after postoperative deep sternal wound infection.
Tocco MP1, Costantino A, Ballardini M, D'Andrea C, Masala M, Merico E, Mosillo L, Sordini P.

The respective incidence of SWI for CABG, isolated valve, or combined procedures were 2.8%, 1.1%, and 3.2%

Eur J Cardiothorac Surg. 2008 Feb;33(2):232-8. Epub 2007 Dec 21.
Algorithm for primary closure in sternal wound infection: a single institution 10-year experience.
Poncelet AJ1, Lengele B, Delaere B, Zech F, Glineur D, Funken JC, El Khoury G, Noirhomme P.

(-50 to -100 mm Hg) stabilize the sternum as efficiently as high negative pressures (-150 to -200 mm Hg).
Mokhtari A, Petzina R, Gustafsson L, Sjögren J, Malmsjö M, Ingemansson R. Sternal stability at different negative pressures during vacuum-assisted closure therapy. Ann Thorac Surg. 2006;82:1063–1067. 

Duration: 3週--> definite therapy


Molecular mechanisms of RIP, an effective inhibitor of chronic infections

Int J Artif Organs 2010; 33(9): 582 - 589
"RNAIII inhibiting peptide (RIP), a linear heptapeptide, is very effective in treating severe polymicrobial infections, including drug-resistant staphylococci like MRSA."

Biofilm 示意圖:

Biofilm-based wound-care algorithm
Journal of Wound Care, Apr2008, Vol. 17 Issue 4, p145-155, 9p, 5 Color Photographs, 1 Black and White Photograph, 2 Diagrams, 3 ChartsDiagram; found on p150

A study of biofilm-based wound management in subjects with critical limb ischaemia.