Associations between patient, treatment, or wound-level factors and venous leg ulcer healing: Wound characteristics are the key factors in determining healing outcomes.

Chronic venous leg ulcers are challenging to heal and often recur. This has a significant impact on older individual health and is a financial burden on health care resources. This study aimed to identify factors associated with the healing of venous leg ulcers via secondary examination of data from a previously published prospective randomized controlled trial of elastic and inelastic compression systems. The data from the 45 patients who finished the trial was reanalyzed for a hypothesis generating study. Larger ulcers, higher exudate levels, larger calf circumferences, and longer ulcer duration at baseline were associated with lack of healing at 12 weeks. There was some evidence that NSAID use was associated with an increased likelihood of nonhealing (unadjusted OR for healing, 0.13, 95% CI (0.02, 0.70)). There was no evidence that other variables, including gender and BMI, were associated with healing. The key risk factors for wound healing are largely wound based or inherent to wound development, as these were found to be the factors with the strongest associations in the analysis. Future research should address how and why these factors are associated with wound healing over a longer time frame and explore how NSAIDs may affect wound healing outcomes.

A mathematical model of the use of supplemental oxygen to combat surgical site infection.

Infections are a common complication of any surgery, often requiring a recovery period in hospital. Supplemental oxygen therapy administered during and immediately after surgery is thought to enhance the immune response to bacterial contamination. However, aerobic bacteria thrive in oxygen-rich environments, and so it is unclear whether oxygen has a net positive effect on recovery. Here, we develop a mathematical model of post-surgery infection to investigate the efficacy of supplemental oxygen therapy on surgical-site infections. A 4-species, coupled, set of non-linear partial differential equations that describes the space-time dependence of neutrophils, bacteria, chemoattractant and oxygen is developed and analysed to determine its underlying properties. Through numerical solutions, we quantify the efficacy of different supplemental oxygen regimes on the treatment of surgical site infections in wounds of different initial bacterial load. A sensitivity analysis is performed to investigate the robustness of the predictions to changes in the model parameters. The numerical results are in good agreement with analyses of the associated well-mixed model. Our model findings provide insight into how the nature of the contaminant and its initial density influence bacterial infection dynamics in the surgical wound.