By Michel H.E. Hermans, MD
In my previous blog, I mentioned the lack of innovative ways of early detection of infection in the context of not having seen a great deal of innovation at the last SAWC. Privately, I received some questions and comments about C-reactive protein as a marker.
C-reactive protein (CRP) is produced by the liver. An increased level of CRP indicates an inflammatory process, but this test is not specific. It may reflect a (serious) infection being the reason for the inflammatory process, but CRP is also raised in many non-infectious processes such as ischemic heart disease, rheumatoid arthritis and many others.
Unfortunately, increased CRP levels do not seem to be a reliable marker for infections in chronic wounds, though a decrease versus baseline levels (as opposed to absolute levels) seems to correlate with clinical improvements in the wound itself.1 Measuring CRP may also help in distinguishing infectious from inflammatory causes of erythema in patients with venous leg ulcers.2 In particular, finding elevated CRP levels in combination with an elevation of procalcitonin was found to be a strong indication of infection in patients with diabetic foot ulcers.3
The studies mentioned here were all done with small numbers of patients, as is the case with other similar studies on CRP and chronic wound infection. CRP measurements alone are generally not considered a fool-proof way of showing—or excluding—infection.
An interesting development from the UK is a dressing that will glow when the oxygen levels in the wound are (too) low. This, of course, could be an indication of the presence of necrosis, hampered circulation or other detrimental circumstances. The article in the Daily Mail does not mention any other properties of the dressing (i.e. does it handle exudate well, is it moisture retentive) but the approach in itself is interesting since it allows indirect inspection of the wound – without removal of the dressing. To my knowledge, the product is not yet on the market anywhere. It would be cool if it glows when the wound is healing, the reverse of what it currently does, but that would, no doubt, require a different technology.
Another new approach has to do with rapidly identifying or excluding the presence of bacteria using fluorescence imaging. When illuminated with specific wavelengths, microorganisms emit intrinsic fluorescent signals which can be detected and analyzed. Using these specific wavelengths in a handheld device allows the clinician to see whether or not bacteria are present. The technique was tested in a small trial in Canada where it was used to guide debridement and analyze the success of debridement (absence of bacteria). The trial was reported at the last SAWC meeting4 (I missed that one, probably too exhausted from the meeting itself).
We all know that the presence of bacteria does not necessarily indicate infection and the poster is not clear whether only planktonic bacteria are shown or whether the technique works with biofilms as well (presumably it does since some patients in the trial had chronic wounds). Perhaps the company can provide feedback on this question. Still, this new approach may provide additional help in early detection of a major problem in wounds, infection.
So, there are some new things coming along, including interesting technologies which will hopefully lead to a positive outcome on treatment.
1. Liu T, Yang F, Li Z, Yi C, Bai X. A prospective pilot study to evaluate wound outcomes and levels of serum C-reactive protein and interleukin-6 in the wound fluid of patients with trauma-related chronic wounds. Ostomy Wound Management. 2014;60(6)30-7.
2. Goodfield MJD. C-reactive protein levels in venous ulceration: An indication of infection? Journal of the American Academy of Dermatology. 1988;18(5):1048-52.
3. Jeandrot A, Richard JL, Combescure C et al. Serum procalcitonin and C-reactive protein concentrations to distinguish mildly infected from non-infected diabetic foot ulcers: a pilot study. Diabetologica. 2008;51(2):347-52.
4. DaCosta RS, Kulbatski I, Lindvere-Teene L et al. A Point-of-Care Autofl¬uorescence Imaging for Real-time Treatment Guidance of Bioburden in Chronic Wounds: First-in-Human Results. Poster presented at: Symposium on Advanced Wound Care; October 16-18, 2014; Las Vegas, NV.
About the Author
Michel H.E. Hermans, MD, is an expert in wound care and related topics, trained in general surgery, trauma care and burn care in the Netherlands. He has more than 25 years of senior management experience in the wound care industry. He has conducted a large number of clinical trials relating to devices and drugs aimed at wound care and related indications and diseases. Dr. Hermans speaks internationally and has authored many published works relating to wound management.
The views and opinions expressed in this blog are solely those of the author, and do not represent the views of WoundSource, Kestrel Health Information, Inc., its affiliates, or subsidiary companies.
The views and opinions expressed in this blog are solely those of the author, and do not represent the views of WoundSource, HMP Global, its affiliates, or subsidiary companies.