Outcomes Research—Measuring Wound Outcomes

The measurement of cutaneous wounds in order to detect the progression of a disease is a routine part of medical practice. Although measurement technology has evolved continuously in all fields of medicine, its direct application to cutaneous disorders has increased recently.¹ Only in the past decade has significant research been undertaken to further develop techniques specific to examining the skin. Advances in both the technology of imaging and computer systems have greatly supported this process and improved its clinical relevance.
Assessment of any wound should begin by determining the extent of the involved area. Because the extent of a wound changes dynamically, repeated systematic assessment is necessary. The total wound extent is based on the wound dimensions and the tissue level involved. The clinical evaluation of the extent of tissue involvement due to a skin lesion, and the way a lesion evolves over time, are often assessed according to the common sense and memory of the clinician. Evaluations are typically performed based on clinical experience, using very basic, low-tech equipment to make objective measurements. The determination of wound extent may be accomplished by either noninvasive or invasive technologies. Noninvasive wound assessment includes the measurement of perimeter, maximum dimensions of length, width, and depth, surface area, volume, and determination of tissue viability.² A wound can be further described using various parameters, which include duration, blood flow, oxygen, hardness, inflammation, pain, and coexisting systemic factors. These parameters are clues to the definition of the cause, pathophysiology, and status of the wound, but the authors believe that a complete and detailed history and physical examination are also fundamental.

Venous Leg Ulcers
Chronic venous leg ulcers affect about 1.5% of the population and represent a considerable medical and social problem.³ The elderly patient is commonly affected by this pathology, often suffering from concomitant chronic pathologic conditions that may render the patient an invalid, profoundly reduce quality of life and often lead to psychological disorders,such as depression. New treatments for these pathologies have led to improvements in ulcer management and in the quality of assistance provided by medical and paramedical staff, but wound monitoring methodologies have not kept pace with this progress. The techniques used to obtain a valid wound assessment are currently based on the use of transparent acetate sheets, which are positioned on the lesion so as to trace its perimeter manually, measuring the depth of the lesion by placing a cotton swab inside it, or filling the lesion cavity with hypoallergenic material to produce a cast, which is then measured to obtain wound volume. However, most clinical diagnoses are made on visual observation. There is only one reliable, standardized, visual wound assessment tool content validated for all chronic wounds,⁴ the Bates-Jensen Wound Assessment Tool, adapted from the valid, reliable, Pressure Sore Status Tool.⁵ Such visual assessments are subjective depending on the experience of the professional evaluating the wound.
Outcomes in venous leg ulcer treatment have become more consistent recently since the introduction of initial wound healing rates to predict complete healing.⁶ The utility of determining early in the course of a given therapy whether or not an ulcer will eventually heal is greatly beneficial in clinical and research areas of wound care. Several healing rate parameters have demonstrated promise in this capacity: wound edge migration, change in wound area, and percentage change in area, are dependent on wound geometry (length, width). Of all the healing rate parameters assessed, early percent reduction in wound area has been the most reliable in predicting complete venous ulcer healing.^7–9
Gilman¹⁰ suggested an equation which uses wound perimeter to calculate the linear advance of epithelial migration at the wound edge, so that it may be used to correct for differences in wound size and shape, and to assess the prognostic role of the initial healing rate. Margolis¹¹ confirmed a significant correlation between Gilman’s equation for linear advance as a predictor of venous leg ulcer healing, but reported that area estimated as longest wound length x longest width was more strongly correlated (Pearson r² = 0.78) with actual area of large wounds than perimeter-based estimates (Pearson r² = 0.52).¹² Looking at prognostic factors for the healing of venous leg ulcers, Falanga and Sabolinsky¹³ reported that an initial healing time of 0.1 cm/week or greater predicts healing, while rates of 0.6 cm/week or less predict nonhealing. While it is generally agreed that both percent reduction in wound area and measurement of linear epithelial advancement differentiate healing from nonhealing wounds; the simple product of wound length x width Gelfand et al⁷ used in more than 29,000 patients with venous ulcers to calculate percent reduction in wound area provides, “a proven prognostic index for clinical practice.”¹⁴
Today, the use of computer-based devices to measure venous ulcer length, width, and depth and calculate both percent reduction in wound area and linear epithelial advancement significantly facilitate data acquisition, elaboration, and storage. It is important to record venous ulcer depth, because full-thickness venous ulcers can take twice as long to heal as same-etiology, partial-thickness ulcers.⁴ In addition to standardized diagnosis, history, and physical examination of the patient and the venous ulcer, a full and correct charac-terization of the level of tissue damage should be carried out by analyzing two distinct groups of parameters: dimensions such as length, width, or depth, and chromatic parameters, such as the colors of granulation or necrotic tissue in the wound bed, pallor, or erythema of surrounding skin.

Diabetic Foot Ulcers
Diabetic foot ulcers (DFUs) represent one significant complication in patients with diabetes and are the principal cause of amputation in these patients. Skin and wound measurements are essential in DFUs in order to monitor the tissue repair process and prevent further complications, such as wound infection. The prevention and management of DFUs may be divided into 3 phases, according to Piaggesi et al.¹⁵ In the early pre-ulcerative phase there is a need to quantify the risk of peripheral neuropathy, which affects 50% of patients, and peripheral vascular disease (PVD), which affects up to 40% of patients with diabetes.The combined use of a monofilament and the vibration perception threshold with a biothesiometer to test the sensitivity has provided easily acquired and reproducible data in patients at risk.¹⁶ Transcutaneous oxygen tension measurement is a well established technique for evaluating local ischemia in patients with diabetes and PVD, and there is broad consensus that values < 40 mmHg are an indicator of critical ischemia.¹⁷ Wound measurement techniques in the ulcerative phase of DFUs can differ according to the degree of tissue damage, but they relay length, width, and depth of wound characterization. For example, as with venous ulcers, early percent area reduction predicts DFU healing.¹⁸ Moreover, Jude et al¹⁹ reported that effects on diabetic foot ulcer depth reduction may be among the earliest significant responses elicited by a treatment modality. In addition, changes in patient-reported pain or foot temperature and radiological assessment, can alert clinicians to potential bone and joint involvement.¹⁸ The final phase, which is defined as the post-ulcerative phase, deals with skin measurement techniques that can evaluate the risk of DFUs recurring. In this sense, the monitoring of skin hardness by means of durometer testing has provided valid data related to the hyperkeratosis of the plantar area where there is increased pressure.²⁰ Foot biomechanics have also been investigated in static and dynamic conditions in order to identify and quantify the area at risk of high pressure.
Measuring a wide variety of DFU dimensions, including etiology, morphology, surrounding skin changes, and pathology, is fundamentally important in guiding care decisions for these complex chronic wounds.

Pressure Ulcers
The management of chronic wounds,such as pressure ulcers, requires an overall assessment of the general health status of the patient together with a focus on the wound history and wound characteristics. The assessment should start from a baseline recording of location, size, depth, and condition of the wound bed. As with venous ulcers, monitoring the percent reduction in pressure area will differentiate a healing ulcer from a nonhealing ulcer during the first 2 weeks of care.²¹
These clinically assessed parameters represent a picture of the wound and serve as an evaluation tool for healing as well as a guide for selection of treatment modalities.⁴
Anatomical location is important for the definition of the healing potential of the wound and must always be recorded in the patient file.
Another essential aspect of clinical assessment is the determination of the nature of tissue involvement. In the case of pressure ulcers, as with venous ulcers, full-thickness pressure ulcers take twice as long as their partial thickness counterpart to heal.⁴ In addition to the 4-stage classification described below for evaluating the extent of pressure ulcer tissue damage, special attention is recommended in evaluating richly pigmented skin²² and deep tissue damage.²³
Grade I pressure ulcers appear as a defined area of persistent redness, which does not disappear after finger compression. Grade II is a superficial ulcer and clinically presents as an abrasion, blister or shallow crater involving epidermis, dermis or both.A Grade III pressure ulcer presents clinically as a deeper crater involving damage or necrosis of subcutaneous tissue, with or without undermining of surrounding tissue. Grade IV pressure ulcer is an extensive destruction of muscle, bone, joint capsule or tendon.²⁴
The presence of undermining tissue is common in pressure ulcers, reflecting a necrosis of the subcutaneous fat tissue; it is directly correlated to the severity of destruction. A careful evaluation of the location and extent of sinus tracts or undermining must be performed in full thickness wounds that are complicated by shear forces, such as a pressure ulcer.²⁵ A simple cotton-tipped applicator may be useful in assessing the undermining of wound edges or for documentation of the extent of sinus tracts.
Assessment of the surrounding skin and wound edges may be a source of additional information for the diagnosis and treatment of the wound. The edge should be assessed for the presence of new epithelial tissue, while surrounding skin may be characterized by the occurrence of discoloration, maceration, erythema, paleness,or erosion. Palpation of the skin may indicate the presence of an indurated area, such as in lipodermatosclerosis or in Grade I pressure ulcers.
Maceration of the wound margin may suggest an excess of exudates, possibly due to an inadequate choice of dressing or uncontrolled edema, or may be an early sign of local infection. Multiple organisms commonly colonize pressure ulcers even in the absence of clinical signs of infection. If infection is clinically suspected, the significance of quantitative laboratory tests must be critically evaluated and drug susceptibility tests must be considered, according to the clinician’s experience and the evidence from the literature.²⁶
The final outcome of infected pressure ulcers depends on the balance between factors that promote further complications and those that lead to their resolution.²⁷ The host defense mechanisms are particularly relevant in infected pressure ulcers, because in these cases patients are generally critically ill and have already received several courses of antibiotic therapy, in addition to wound management. Because there are 4 pressure ulcers stages, according to the EPUAP scoring system,²⁸ it is essential to further differentiate the level of infection into superficial and deep tissue, considering also that systemic involvement may be reached after rapid progression. Superficial infection mainly affects Grade II pressure ulcers and is characterized by the classic signs and symptoms of infection: delayed healing, change in color of the wound bed, abnormal odor, increased exudate and pain, and friable granulation tissue. In this case, the use of topical antiseptics has been found to be of great benefit in controlling the bacterial burden, while at the same time avoiding systemic complications.²⁹ Deep infection is a frequent complication of Grade III and Grade IV pressure ulcers and is characterized by an increase in warmth, tenderness, and pain.There may also be extended erythema, reaching to the bone, and new areas of breakdown. Osteomyelitis is a common complication in infected pressure ulcers—Staphylococcus aureus is the cause of infection in approximately 60% of all cases.³⁰ The diagnosis of osteomyelitis is obtained by blood culture and bone biopsy; a prolonged parenteral therapeutic regimen of 4 to 6 weeks is often required.³¹

Conclusion
Wound assessment represents an essential step in wound management. The techniques involved play an important role in correct diagnosis and proper treatment of chronic, invalidating lesions, such as hard-to-heal ulcers. However, what is required is a uniform, standardized, and well-established approach to wound assessment that utilizes noninvasive measurements to identify a management strategy, determine proper standards of treatment, and appropriately reassess progress to healing together with specific modifications of intervention. The use of skin measurement techniques to improve the management of wounds remains a novel area for most practitioners, since the traditional approach continues to be used for clinical inspection. The main goal of current research is to create a system that monitors the qualitative and quantitative evolution of wounds with an easy-to-use technological system that is able to produce an objective wound status evaluation and allows the evolution of the wound to be monitored with measurable attributes. Dedicated wound photography, high frequency ultrasound assessment, laser Doppler perfusion imaging, confocal microscopy, transcutaneous oximetry, pH measurement, and magnetic resonance imaging, are some of the currently available technology being used to specifically examine different types of wounds. The objective assessment of chronic wounds during tissue repair will become a specific aspect within wound management, which will not replace the clinical assessment of expert caregivers, but may bring numerous advantages in terms of understanding and awareness of each wound management challenge.