Early Detection of Pressure Injury Using a Forensic Alternate Light Source

Heather Hettrick, PT, PhD, CWS, CLT-LANA, CLWT; Cheryl Hill, PT, PhD, DPT; Patrick Hardigan, PhD

Disclosures

Wounds. 2017;29(8):222-228. 

In This Article

Results

Seven participants completed the study. The findings from the data collection sheets were transferred into an Excel spreadsheet (Microsoft Corporation, Redmond, WA) for statistical analysis. Participant data were entered into the spreadsheet for each week data were collected. Findings were reported for each wavelength and noted as either "M" for missing (photo not clear or unable to obtain), "Y" for yes indicating absorption, or "N" for no indicating no change or no absorption.

Descriptive statistics were calculated for all wavelengths. Two analyses were conducted to look for relationships between wavelength and detecting injury (absorption). For the first analysis, different wavelengths were grouped into 2 categories: (1) 455 Y and 475 Y versus (2) Other. For the second analysis, the groups were extended: (1) 455, 455 Y, 475, 475 Y, 495, and 515 versus (2) Other. To look for differences under both scenarios, 2 chi-square (c2 tests of independence were run to look for relationships between wavelength and the number of detected injuries (absorption). Results are as follows:

  • For the first analysis, the percentage of findings did not differ by grouping (c2 [2, N = 1540] = 2.71, P = .257).

  • For the second analysis, the percentage of findings did differ by grouping (c2 [2, N = 1540] = 11.95, P = .002). Significantly more tissue damage (absorption) was visible under the wavelength grouping 455, 455 Y, 475, 475 Y, 495, and 515 than other combined wavelengths.

Participants who presented with nonblanching erythema and existing ulceration in ambient light (Stage 1 pressure ulcer, Unstageable pressure ulcer) showed significant tissue absorption indicating the actual scope and magnitude of the tissue trauma under ALS. Figure 1 shows a participant's heels in ambient light with visible tissue erythema. Figure 2 is of the same participant's heels as viewed under ALS using 415-nm violet wavelength. Note the marked absorption (or darkening) in the tissues indicates the presence of blood in the subcutaneous tissues. This provides greater detail as to the extent of tissue trauma not visible to the naked eye in ambient light. Additionally, in the body region observed for this study, participants with scars, areas of previous injury, and pigmentary changes also showed significant absorption at those sites beyond what was noted in ambient light. Figure 3 depicts a participant's foot with visible yet faint scar tissue and pigmentary changes in ambient light. Figure 4 shows the same participant's foot under ALS using 475-nm blue wavelength with a yellow lens. The areas of scar tissue and previous injury are well demarcated and more visible under the ALS than in ambient light alone. This is clinically relevant because noting areas of scar tissue or previous injury is important, as these areas are at greater risk for subsequent breakdown or reinjury due to reduced tensile strength. Figure 4 also depicts yellow patches of fungus that fluoresce under ALS; this was not visible in Figure 3 when viewed in ambient light alone.

Figure 1.

A Stage 1 pressure ulcer in ambient light with visible tissue erythema on a participant's heels.

Figure 2.

The same participant's heels (as Figure 1) viewed under alternate light source using 415-nm violet wavelength.

Figure 3.

A participant's foot with visible yet faint scar tissue and pigmentary changes in ambient light.

Figure 4.

The same participant's foot (as Figure 3) under alternate light source using 475-nm blue wavelength with a yellow lens.

These combined findings indicate that ALS can detect tissue trauma not readily visible to the naked eye, providing further details regarding extent and magnitude of tissue involvement. This noninvasive tool could help identify patients in the early stages of tissue trauma as well as screen for sites of previous injury that are at risk for subsequent breakdown.

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