The Acceptability and Efficacy of Polyhexamethylene Biguanide Post-Low-Frequency Ultrasonic Debridement in Reducing Bacterial Burden for Patients with Chronic Wounds

Alison Vallejo

doi:10.25907/00092

Background: Chronic wounds can be difficult to heal or sometimes never heal. Current evidence indicates that wound biofilm can interfere with healing when standard care is unsuccessful. Biofilm consists of bacteria encased in a matrix that provides protection from external and chemical environments. Combining two treatments targeting wound biofilm plus standard care for the wound type may improve outcomes. Aim: This research aimed to determine the safety, acceptability and efficacy of combining low-frequency ultrasonic debridement (LFUD) and the antiseptic polyhexamethylene biguanide (PHMB) post-treatment on adults with chronic wounds. Methods: This research was conducted using a pragmatic design and a mixed methods methodology with two phases. Phase 1 involved collecting and analysing qualitative data from an exploratory case series of four cases with five wounds. The patients presented with non-healing wounds and suspected microbial involvement. They were subjected to the combination of the LFUD, PHMB and other antimicrobial dressings plus standard care for their wound types. The data for this phase included a retrospective healthcare record audit, wound observations and structured individual interviews. The interview data captured the patients’ experiences about the acceptability of the dual therapy and information regarding the feasibility of Phase 2. Phase 2 investigated the use of LFUD and PHMB (an antiseptic) compared to LFUD and standard practices (no antiseptic) via a single-blinded, randomised control trial (RCT) of 50 participants (1:1 intervention and controls) over 12 weeks. Quantitative data were collected and analysed. The primary outcome was the reduction of the bacterial load measured via colony-forming units (CFUs) and bacterial type from wound swabs. Secondary outcomes included wound healing progress, wound size reduction, pain levels and quality of life (QOL) using validated tools. Results: Phase 1 demonstrated that while standard care for the four participants had previously failed to improve healing, the new combination therapy appeared to accelerate healing. It was safe and acceptable with no adverse effects experienced by the participants. Phase 2 demonstrated a significant reduction in CFUs in the intervention group (LFUD and PHMB antiseptic) compared to the control group (no antiseptic at the end of the LFUD treatment) (p < 0.001). There was no difference in complete wound healing between the groups: six in the control group versus four in the PHMB group (χ2=0.5; p=0.47). However, fewer patients deteriorated in the PHMB group than the control group (44% vs 4%, χ2=8.42, p=0.003). More participants in the control group had to withdraw from the study because their wound size increased or they were admitted to hospital and could not return to the trial. Eighty per cent of the intervention group were followed to the study’s end compared to 52% in the control group (χ2=4.3, p=0.03). The proportion of wounds that reduced in size was also greater in the intervention group than the control group (61% vs 12.7%, χ2=51, p=0.019). Pain levels demonstrated a statistically significant reduction in the PHMB group at week six (p=0.04). QOL scores showed no difference between the groups. Conclusions: Chronic wounds with suspected biofilm can heal if the treatment is multifactorial. The combination of techniques used in this research was acceptable to patients and effective on the wound bioburden of chronic wounds in adults and is a promising new standard of care treatment option. The use of LFUD with an antiseptic, such as PHMB, is recommended to accelerate wound healing. The uptake of this novel combination treatment may reduce the burden of chronic wounds for the individual, nurses and the wider healthcare system. Embedding a qualitative arm into the study evidenced the acceptability of the intervention, informed the trial design and ensured the feasibility of the RCT. Future research requires larger numbers and a longer follow-up time to sufficiently power the analysis of such data. Further, the effects of multiple covariates need to be considered.

The Acceptability and Efficacy of Polyhexamethylene Biguanide Post-Low-Frequency Ultrasonic Debridement in Reducing Bacterial Burden for Patients with Chronic Wounds

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