Study of the relation between subcutaneous wound drainage after midline sternotomy and surgical site infections in obese patients

Introduction
Surgical site infection (SSI) is an important morbidity postoperatively after midline sternotomy in patients undergoing cardiac surgery. Collected blood and serous fluids can get infected, which is one of the many factors responsible for surgical site infection, especially in obese patients.

Aim
To observe the association of SSI with and without prophylactic use of subcutaneous wound drainage in obese patients undergoing cardiac surgery via midline sternotomy.

Material and methods
A retrospective observational study of 152 obese patients who underwent cardiac surgery via midline sternotomy was conducted. Data were analysed after retrieving records between two groups of patients – those who received a prophylactic subcutaneous wound drain (group A) and those who did not (group B) after surgery in terms of superficial and deep surgical site infection including mediastinitis, need for second surgery, VAC dressing, hospital stay and need for readmission.

Results
Retrieved data showed that 27 obese patients of the 128 (21%) developed SSI after cardiac surgery via midline sternotomy. Deep sternal wound infection (DSWI) was significantly higher in patients from group B than group A. Multivariate analysis did not show a statistically significant decrease due to suction drains. Superficial infection, though higher, was not statistically significantly different between the two groups. The hospital stay was found to be longer and statistically significant in group B patients than group A.

Conclusions
There was a decrease in the incidence of DSWI in obese patients receiving prophylactic subcutaneous wound drainage after cardiac surgery via midline sternotomy but the difference was not statistically significant.