Quantitative estimation of exudate volume for full-thickness pressure ulcers: the ESTimation method

Abstract

To develop an equation for the estimation of exudate volume in millilitres, for full-thickness pressure ulcers, according to wound characteristics. 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. 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. 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. The authors have nothing to declare.