Negative Pressure Wound Therapy with Instillation: Anti-Microbial Solution or Normal Saline for Long Term Success

Background: Negative-pressure wound therapy with instillation is a widely utilized adjuvant in the treatment of complex wounds. Anti-septic solutions are often preferred for instillation, however the mechanism of this therapy may be independent of instillation compounds. This is the first study to analyze long-term outcomes between normal saline and a common antimicrobial solution in treating infected wounds by negative-pressure wound therapy with instillation.  

Methods: This was a single-center retrospective study comparing the long-term course of patients receiving 0.9% normal saline or 0.1% polyhexanide plus 0.1% betaine as instillation for wounds requiring hospital admission and operation. No exclusions were set for wound characteristics, patient demographics or comorbidities. Outcomes were measured over a 5-year period and included rates of wound healing, dehiscence, recurrence, additional operations, amputations, and mortality. Mortality was obtained using electronic medical records as well as a commercial obituary database. Statistical significance was set at p  

Results: 42 individuals received normal saline and 41 received 0.1% polyhexanide plus 0.1% betaine solution. There was no statistically significant difference in initial wound characteristics, comorbidities, patient demographics, or any measured outcomes between cohorts. Rates of dehiscence, wound recurrence, and operations in the normal saline and anti-septic cohorts were 6.3% and 5.6%, 9.4% and 5.6%, and 14.3% and 9.8%, respectively. Amongst patients requiring further surgery, mean time to wound closure was 104 days and 130 in the normal saline and anti-septic cohorts, respectively (p=0.81). 14.3% of the normal saline and 22% of the anti-septic cohorts required amputations during the 5-year period (p=0.36). Amputations were predominantly minor (83% and 55% of amputations in the normal saline and anti-septic cohorts, respectively). 5-year mortality was 24% and 17% in the normal saline and anti-septic cohorts, respectively, with no statistically significant difference (p=0.45).   

Conclusion: Several options exist for instillation solution in negative-pressure wound therapy and these results provide valuable information suggesting the long-term efficacy of normal saline is equivalent to that of 0.1% polyhexanide plus 0.1% betaine solution for surgically treated wounds. The clinically efficacy, accessibility and cost advantage of normal saline can potentially expand the utilization of this beneficial therapeutic technology for larger patient populations.