14 Conventional versus instillation NPWT in the treatment of surgical site infections—an interim analysis of ongoing prospective trial
Authors: Popivanov Georgi , Penchev D , Chipeva S , Stefanov D , Konaktchieva M , Kjossev K , Paycheva Ts , Dimitrov P , Marangozov S , Mutafchiyski V 
Published: February 2025

Abstract

Aim
Approximately 9 million HAIs occur yearly worldwide or 5–15% of all admissions. According to a recent systematic review the cumulative incidence of SSIs is 11%. According to the Middle East Expert Forum, NPWT with instillation (NPWTi) offers the following benefits over the conventional NPWT ‘reduction in bioburden, decreased time to wound closure, reduced infection rates, decreased length hospital stay and fewer additional surgical procedures’. However, the quality of the published literature is low and sound evidence for the benefit of NPWTi is still lacking. The present study aims to compare the effectiveness of NPWT and NPWTi using an improvised system with continuous lavage with saline and chlorhexidine in superficial and deep SSIs after conventional laparotomy or laparoscopic abdominal surgery.

Material and Methods
The study analyzes a prospective database encompassing 17 January 2018–25 December 2023. All patients underwent surgical debridement and lavage with 3–5 l saline under anesthesia. Systemic antibiotics were administered according to the antibiogram. In conventional NPWT, the wound was filled with black foam (Granufoam®, KCI) and covered with plastic folio. A continuous pressure of 125 mmHg was applied using the hospital suction system. In NPWTi, the whole wound was filled with Granufoam®. The instillation was performed via gravity from i.v. bag through a drain put within the foam. Chlorhexidine 0.1% 300 ml in 700 ml saline was used for continuous instillation three times daily (3 l per day) on the background of continuous pressure of 125 mmHg. Double masking was applied (Investigator and Outcomes Assessor). Primary outcomes were the rate of wound closure and 30-day infection recurrence rate. Secondary outcomes were hospital stay, number of OR visits, and time to wound closure (suture or flap). The study is registered in ClinicalTrials.gov with ID: NCT06014788.

Results
Out of 4765 operated patients for the last five years, the HAIs and SSIs were 3.1% (n = 149) and 2.6% (n = 125). The distribution of ESKAPEE pathogens was following: E. faecium—34.4%, S. aureus—8%, K. pneumoniae—10.4%, A. baumanii—8%, P. aeruginosa—11.2%, Enterobacter—7.2%, E. coli—32.8%. A total of 62 consecutive patients (standard NPWT—41, NPWTi—21) have been included. Conventional NPWT managed the first consecutive 30 cases. The next 21 were treated with either conventional NPWT or NPWTi at the discretion of the operating surgeon, whereas the last 11 were treated with NPWTi. There was deep SSI in 32 cases—19 in NPWT and 13 in NPWTi. The mean age was 60.8 versus 57 years. The rate of wound closure was 93% versus 91%, the 30-day infection recurrence rate was 2% versus 10%, and the complication rate was 2% versus 10%. The secondary outcomes were as follows: hospital stay—19.3 versus 20.8 days, number of OR visits—3.71 versus 2.9, and time to wound closure (suture or flap)—11.8 versus 11.6 days. None of the abovementioned differences was statistically significant.

Conclusion
The interim analysis of this prospective ongoing trial demonstrates no significant benefit of NPWTi in comparison to the conventional NPWT in superficial or deep SSIs after laparotomy.