Longitudinal Study of Stage III and Stage IV Pressure Ulcer Area and Perimeter as Healing Parameters to Predict Wound Closure
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Documentation of healing progress is central to the plan of care for patients with a pressure ulcer. Several studies have shown that a reduction in wound area is a predictor of chronic wound healing, but data about pressure ulcers are limited. Furthermore, consensus is lacking as to which wound characteristics such as volume, area, and perimeter should be measured and what methods or tools to use when collecting measurements. This hampers comparisons among research studies and their eventual translation into clinical practice. The purpose of this longitudinal, repeated measurements study was to calculate healing parameters using wound area and perimeter measurements and evaluate their potential to predict closure. Twenty-seven (27) patients with 31 Stage III and Stage IV pressure ulcers participated in the 42-day study.
Wound length, width, and perimeter were measured at 15 time points or until healing, and the following healing parameters were calculated: absolute area, percent area reduction, mean percent area reduction, trajectory, and three variations of the linear healing parameter. Ulcer size at day 0 was a significant predictor of time to heal (P = 0.0231). Smaller wounds required less time, but initial size did not influence wound outcome (P = 0.3537). Among ulcers that closed 81% or more of their original area, the initial linear healing rate (4 weeks) was 0.16 ± 0.02 cm/week and mean percent area reduction was 35.37% + 4.83, compared to 0.021 + 0.02 cm/week and – 4.66% + 6.24, respectively, for ulcers that closed 40% or less of their original area. Percent area reduction and linear healing parameters all were predictive of wound outcomes. Percent area measurements are easiest to determine but sensitive to initial wound size. The linear healing parameter requires calculation of both wound area and perimeter, but it is independent of initial wound size and yields rates directly comparable among wounds. These findings confirm that change in wound size after 4 weeks of care is a predictor of healing Stage III and Stage IV pressure ulcers. Future research studies should include other wound characteristics and patient comorbidities to further refine acceptable rates of wound closure.
Keywords: wound healing trend, full-thickness pressure ulcer, wound assessment, trajectory, wound area
Index: Ostomy Wound Management 2011;57(10):50–62
Potential Conflicts of Interest: This work was supported by the Telemedicine and Advanced Technology Research Center (TATRC) at the US Army Medical Research and Material Command (USAMRMC) through award W81XWH-05-1-0401.
The goal of pressure ulcer research is to evaluate optimal methods to provide care and facilitate healing. Evaluation of treatment effectiveness is accomplished through assessment and documentation of changes in the pressure ulcer until closure.
Complete closure or accelerated closure are often endpoints in clinical studies, but chronic wounds usually require extended periods of time for complete closure, making trials lengthy and expensive.1 Surrogate markers (early predictors of healing or delayed healing) would enhance the assessment of treatment effectiveness and allow practitioners to modify and tailor treatments according to the individual patient’s response.2
Researchers have suggested a range of potential predictors of pressure, venous, and diabetic foot ulcer healing, including perfusion and dietary protein3; ulcer stage and wound area4; wound width, length, area, and perimeter5; and rate of healing.