The impact of Manuka honey dressings on the surface pH of chronic wounds

Abstract

Chronic non healing wounds have an elevated alkaline environment. The acidic pH of Manuka honey makes it a potential treatment for lowering wound pH, but the duration of effect is unknown. Lowering wound pH can potentially reduce protease activity, increase fibroblast activity and increase oxygen release consequently aiding wound healing. The aim of this study was to analyse the changes in surface pH and size of non healing ulcers following application of Manuka honey dressing after 2 weeks. The study was an open label, non randomised prospective study. Patients presenting consecutively with non healing chronic superficial ulcers, determined by aetiology and no reduction in wound size in previous 3 weeks. Single pH measurements recorded using Blueline 27 glass surface electrode and R 315 pH meter set (Reagecon/Alkem, Co. Clare Ireland). Area determined using Visitrak (Smith & Nephew, Mull, UK) digital planimetry. Apinate ® (Manuka honey) (Comvita, Slough, UK) applied to wounds for 2 weeks after which wounds re‐evaluated. Eight males and nine females with 20 ulcers (3 bilateral) were included: venous, 50% ( n = 10); mixed aetiology, 35% ( n = 7); arterial, 10% ( n = 2) and pressure ulcer, 5% ( n = 1). Reduction in wound pH after 2 weeks was statistically significant ( P < 0·001). Wounds with pH ≥ 8·0 did not decrease in size and wounds with pH ≤ 7·6 had a 30% decrease in size. A reduction in 0·1 pH unit was associated with an 8·1% reduction in wound size ( P < 0·012). The use of Manuka honey dressings was associated with a statistically significant decrease in wound pH and a reduction in wound size. Elevated pH readings at the start were associated with minimal reduction in size. Surface wound pH measurements may contribute to objective wound assessments, but further research is necessary to determine its exact contribution.