Take Test
Abstract
PURPOSE: To provide practitioners with evidence-based recommendations for measuring wound size.
TARGET AUDIENCE: This continuing education activity is intended for physicians and nurses with an interest in wound care.
OBJECTIVES: After reading this article and taking this test, the reader should be able to:
1. Describe different methods of measuring wound size and their advantages and disadvantages.
2. Discuss a research study conducted to determine the most accurate ruler technique for measuring wounds.
3. Identify evidence-based wound measurement data and recommendations for clinical practice.
Two-dimensional linear wound measurement is a convenient, quick, easy, and inexpensive means to measure a wound. Length and width are frequently used to estimate wound surface area. In turn, the repeated determination of surface area over time assists the clinician in evaluating wound progression or regression and the effectiveness of interventions. The goal of comparability assumes that all members of the wound care team use the same approach in measuring the wound.1 However, this is often not the case.
Several techniques are used to measure the length (L) and width (W) of a wound. After obtaining wound length and width, the clinician multiplies the 2 measurements to obtain the area in squared centimeters (cm2). The most common method of determining wound area is to measure the longest length and width, regardless of head-to-toe orientation, or to measure length and width perpendicular to one another. Other clinicians, however, measure the longest length head-to-toe, followed by the longest width, side-to-side, and at any angle to one another. Another technique is to measure the longest head-to-toe length and the longest width side-to-side, perpendicular to length. Yet another method includes measuring the longest length and the longest width perpendicular to one another, disregarding head-to-toe and side-to-side orientation. The major problem with multiplying these 2-dimensional measurements is that the area estimated is either a rectangle or square, depending on the measurements. If the L and W measurements closely approximate one another, the area calculated would be roughly equivalent to a square, whereas different L and W measurements multiplied together roughly equate to the area of a rectangle.2,3 Wound care providers recognize that wounds are not near-perfect squares or rectangles. Therefore, the estimated area will literally always be greater than the actual area. This was shown to be true especially for a pear-shaped wound.3
EXAMINING THE POSSIBILITIES
For many years, the wound care community has debated over what is considered the "best" or "most accurate" wound measurement. Research found in the literature has typically compared the different techniques for measurement of the wound area. Measuring length and width to estimate wound area is simple and convenient but is generally unreliable for large or irregular wounds.4
In the tracing or planimetry method, the clinician traces the wound perimeter onto a transparency and uses a metric grid to count the number of square centimeters within the wound perimeter. Although this is a relatively easy method with fairly good reliability, planimetry can cause some discomfort during the tracing process. In addition, error arises in the decision whether to include partial squares in the area.5
The Kundin device is a disposable, 3-dimensional, plastic-coated paper wound gauge. Clinicians may use only the length and width measurements when using the device if desired. It is inexpensive and takes minimal time to use; however, the device can cause pain when placed in the wound.6
The computerized wound-measuring technique uses a digital photograph uploaded to a computer software using the Verge Videomater (VeV) (Vista Medical, Winnipeg, Canada). This noncontact method eliminates the chance of wound discomfort and has very good interrater and intrarater reliability.3
Stereophotogrammetry (SPG) is a technology that is quite similar to the VeV technique. It is the science of measurement from photographs when an overlapping stereopair of photographs is used and allows 3-dimensional imaging to be extracted.
DETERMINING THE BEST MEASUREMENT TECHNIQUE
Cutler et al7 compared the tracing and photography techniques and found a high correlation when comparing the results of the 2 methods (r = 0.98, P < .001). Thomas and Wysocki8 compared the following 2-dimensional measurement methods: acetate tracings, photographs, and the Kundin gauge. They found the acetate wound perimeter tracings to be more accurate in determining actual wound area than wound photographs or the Kundin wound gauge. Griffin et al9 found no difference between photography and transparency methods. Stereophotogrammetry was found to be the most accurate and reliable method in several studies.3,10,11 Langemo et al3 compared SPG, the Kundin gauge, planimetry tracing, and ruler length and width on 3 plaster of Paris wound models. The most biased (greatest measurement error) technique was the ruler length and width. However, this method was the second most accurate method following SPG.
Keast et al12 reported that research indicates that measuring the greatest length and the greatest width, perpendicular to the length, is indeed the more valid and reliable method compared with other ruler-based methods.
MAKING A RULING
It would be most helpful to clinical wound care practice and research to use 1 consistent method to measure wounds and estimate wound surface area. This would allow more accurate comparison of measurements and healing/nonhealing over time. As the ruler method is by far the most frequently used, the least expensive, and the quickest, it is necessary to determine which of the ruler length and width measurement techniques is the most accurate. Therefore, the following small study was conducted to determine which of the 4 ruler length and width measurement techniques was closest to actual wound surface area.
METHODS
This evaluative, comparative study used a convenience sample of 4 graduate-degree-prepared, wound care registered nurses with wound care experience ranging from 20 to 35 years. Three plaster of Paris wound models, painted to resemble an actual wound, were used. Wound 1 was L shaped, wound 2 was pear shaped, and wound 3 was fairly symmetrical (Figure 1). Using wound models allowed researchers to eliminate variability that is induced by soft structures (human or animal tissues), thus enabling more precise measurements than possible for in vivo wounds.9 Variability in wound boundary, wound flexibility, and position of patient could thus be avoided.13 Before beginning the study, an accurate measurement of wound area for each wound model was made by an independent aerospace testing authority in Winnipeg, Canada, using a Granite 80LK Coordinate Measuring Machine with absolute accuracy of 0.0002 inch. These calculations served as the control measurements for comparative purposes.
 | Figure 1. PICTURE OF WOUND SHAPESIn a comparative study, 3 plaster of Paris wound models, painted to resemble an actual wound, were used. Wound 1 was L shaped, wound 2 was pear shaped, and wound 3 was fairly symmetrical.Source: The wound models were supplied and measured by Vista Medical, Winnipeg, Manitoba, Canada. |
Raters were blinded as to actual area measurements of the wound models. Raters were provided written instructions. They were asked to measure each of the 3 wound models twice, using the following techniques:
* longest length head-to-toe and longest width side-to-side, perpendicular to length
* longest length and width perpendicular to one another, regardless of head-to-toe orientation or the measurements being perpendicular to one another
* longest length head-to-toe and longest width side-to-side at any angle to one another
* longest length and longest width at any angle, regardless of head-to-toe orientation.
The mean of the 2 measurements for each technique for each wound was used for statistical analysis. Interrater reliability using Cronbach [alpha] was high at r = 0.998.
STUDY RESULTS
A mean of the 4 raters' length and width measurements was calculated, and from this, mean surface area was determined by multiplying length by width for cm2 area for each of the 4 measurements methods for each of the 3 wound models. As actual wound surface area was known, it was possible to determine the percent that each technique overestimated or underestimated the surface area. In wound 1 (L shaped), the mean percent overestimation ranged from 28.9% to 52.9%. In wound 2 (pear shaped), overestimation ranged from 69.3 to 78%, whereas wound 3 (circle shape) overestimation varied from 32% to 42.1%. The fourth technique, longest L and longest W at any angle, regardless of head-to-toe orientation, overestimated actual wound surface area by the greatest percent (wound 1 = 52.9%, wound 2 = 77.4%, wound 3 = 42%). The most accurate technique (least overestimation) for all 3 wounds shapes was method 1, longest L head-to-toe, and longest W side-to-side, perpendicular to length (wound 1 = 28.9%, wound 2 = 69.3%, and wound 3 = 32%; Table 1). The area calculation for the pear-shaped wound was overestimated by a greater percentage than the other 2 wound shapes. The authors remind readers that the greater overestimation occurs for wounds of more irregular shape.
 | Table 1. ACTUAL WOUND AREA, MEAN MEASURED AREA, AND MEAN OVERESTIMATION OF ACTUAL AREA (CM |
Based on these somewhat limited but statistically analyzed results, the researchers recommend that, when length and width ruler measurements are used, wounds would best be measured using the following technique: with a head-to-toe orientation, the longest length head-to-toe, and the widest width side-to-side, perpendicular (90-degree angle) to length.
CONCLUSIONS
Wound assessment is essential to effective wound management, and wounds should be measured each time the wounds are assessed.3,12 Researchers recognize that the most common method currently used to measure a wound is by using a ruler. This method has been found to be reliable.3,4
Results of this study, and those of previous studies, demonstrate that using a ruler to measure the length and width of a wound and multiplying the 2 measurements together result in the wound area measurement much greater than the actual area. This finding is supported by Keast et al12 and Langemo et al,3 and particularly so for larger size wounds,3,4 as well as for more irregularly shaped wounds (eg, pear shaped). Despite deficiencies that may be inherent in a technique, regular assessment, including consistent measurement practices, is clearly better than no measurements being taken.12
This study used only 4 raters; however, the participants were very experienced in wound assessment. The study was based on the use of plaster of Paris wound models to control for wound variability. Similar research remains to be conducted using actual wounds. Yet, given the reality of research based on wound models, the researchers offer 3 recommendations. The first recommendation is that it is critical, for comparative purposes over time, that all clinicians who measure a wound using a ruler use the same technique. Second, while the ruler technique will overestimate wound area, if it is done by the same technique, it should overestimate consistently and thereby allow for comparability. Third, the researchers recommend using the following ruler length and width measurement technique: with a head-to-toe orientation, the longest length head-to-toe, and the widest width side-to-side, perpendicular (90-degree angle) to length.
The researchers do not recommend that clinicians use the longest head-to-toe length and the widest width side-to-side, as this technique was shown to overestimate wound area by greater than 70% on some wound shapes.
REFERENCES
1. Flanagan M. Wound Management. Churchill Livingstone: Edinburgh; 1997. [Context Link]
2. Fette AM. A clinimetric analysis of wound measurement tools. World Wide Wounds. January 2006. Available at: http://www.worldwidewounds.com/2006/january/Fette/Clinimetric-Analysis-Wound-Measurement-Tools.html . Last accessed February 28, 2007. [Context Link]
3. Langemo DK, Melland H, Hanson D, Olson B, Hunter S, Henly SJ. Two-dimensional wound measurement: comparison of 4 techniques. Adv Wound Care 1998;11:337-43. [Context Link]
4. Keast DH, Cranney G. Does wound surface area as measured by length and width reflect true area: analysis of a wound data base. Presented at: Ninth Annual Conference, Canadian Association of Wound Care; November 6-9, 2003; Toronto, Ontario, Canada. [Context Link]
5. Thawer HA, Houghton PE, Woodbury MG, Keast D, Campbell K. A comparison of computer-assisted and manual wound size measurement. Ostomy Wound Manage 2002;48(10):46-53. [Context Link]
6. Kundin JI. Designing and developing a new measuring instrument. Perioper Nurs Q 1985;1(4):40-5. [Context Link]
7. Cutler NR, George R, Seifert RD, et al. Comparison of quantitative methodologies to define chronic pressure ulcer measurements. Decubitus 1993;6(6):22-30. [Context Link]
8. Thomas AC, Wysocki AB. The healing wound: a comparison of three clinically useful methods of measurement. Decubitus 1990;3(1):18-20, 24-5. [Context Link]
9. Griffin JW, Tolley EA, Tooms RE, Reyes RA, Clifft JK. A comparison of photographic and transparency-based methods for measuring wound surface area. Phys Ther 1993;73:117-22. [Context Link]
10. Anthony D. Measuring pressure sores. Nurs Times 1985;81(22):57-61. [Context Link]
11. Bulstrode CJ, Goode AW, Scott PJ. Stereophotogrammetry for measuring rates of cutaneous healing: a comparison with conventional techniques. Clin Sci 1986;71:437-43. [Context Link]
12. Keast DH, Bowering CK, Evans AW, MacKean GL, Burrows C, D'Souza L. MEASURE: a proposed assessment framework for developing best practice recommendations for wound assessment. Wound Repair Regen 2004;12(3 suppl):S1-17. [Context Link]
13. Plassmann P, Melhuish JM, Harding KG. Methods of measuring wound size: a comparative study. Ostomy Wound Manage 1994;40(7):50-60. [Context Link]