Quantitative estimation of exudates volume for full-thickness pressure ulcers: The ESTimation method

Objective: To develop an equation for the estimation of exudate volume in millilitres, for fullthickness pressure ulcers, according to wound characteristics. Method: In a cross-sectional study, 41 patients aged ≤ 60 years with 58 full-thickness pressure ulcers were evaluated. Exudate was collected by covering each wound with a transparent occlusive dressing and the accumulated volume was measured to estimate volume per day. The overall severity of each wound was evaluated by the DESIGN-R tool; a model was then developed to estimate the volume of exudate based on these experimental values. Linear regression analyses were performed to evaluate the precision and accuracy of the model. Results: The model, including exudate score, size score, and total score, showed a higher adjusted coefficient of determination (R2=0.66) than the model with only a traditional exudate score (R₂=0.57). After adjustment for age, inclusion of interaction terms, and modification of bias, a model with continuous parameters was finally developed: exudate volume per day (ml/day) = exp([0.86×exudate score]+ [0.21×size score]+[0. 12×total score]-[0.013×size score×total score]-[0. 04×age]-3.60). Furthermore, a categorical model was developed for clinical simplicity of use. The adjusted R₂ was increased to 0.73 for the continuous model and to 0.77 for the categorical model. There were no apparent biases (p > 0.05) and no correlations between residuals and measured value (p > 0.05) in these models. Conclusion: The equation, including the exudate score, size score and total score of DESIGN-R, as well as age, is called the ESTimation method. It will be useful for clinicians to predict the absolute volume of exudate and to select appropriate dressings for full-thickness pressure ulcers. l Declaration of interest: The authors have nothing to declare.