An Objective Predictor of Wound Healing at the Bedside, Using Long Wave Infrared Thermography (LWIT)

Introduction: Wound healing progression consists of specific cellular processes that may not be visible until clinical symptoms are observed.  A visual assessment may not provide early awareness of wound deterioration, thus delaying specific interventions and progression toward closure.  Methods:Research with pressure injuries (PI) has shown that higher periwound temperature (PWT) vs. wound bed temperature (WBT) resulted in better wound healing (p=0.028).1 The objective was to utilize the WBT and PWT to determine early indications of delayed healing vs. wound progression in chronic wounds beyond only PI.   LWIT images were taken during wound assessments; all wounds had a positive healing progression. The LWIT software measured the mean wound bed temperature (WBT) and the mean periwound temperature (PWT) -within 0.5 cm circumference of the wound. The WBTs and the PWTs were compared, looking at increases or decreases in temperature at the peri-wound.  LWIT Images were collected before wound cleansing or debridement to avoid altering the wound bed temperature measurements.Results:At each assessment of wounds on a positive healing progression, the mean PWT was equal to or warmer than the mean WBT. This data showed venous and venous/arterial mixed etiologies had similar results as PI's; the warmer PWT measurement compared to the WBT correlated with wound progression as an early predictor of wound healing.  Case 1: venous/arterial mix, PWT 0-1˚C > WBTCase 2: venous, PWT 1-1.2˚C > WBTCase 3: venous, PWT 0.3-4.1˚C > WBT                                                                                                                       Case 4: venous, PWT 0.5-0.9˚C > WBT                                                                                                                               Case 5: venous, PWT 0.6-1.5˚C > WBT  Discussion: Temperature is a physiological thermoregulatory mechanism. Cellular and metabolic activity, along with clinical changes, occur during the healing process. Thermal energy may be higher due to inflammation/infection. Lower temperatures can indicate a slower healing rate due to decreased perfusion/oxygen.References:Lin, Y.-H.; Chen, Y.-C.; Cheng, K.-S.; Yu, P.-J.; Wang, J.-L.; Ko, N.-Y. Higher Periwound Temperature Associated with Wound Healing of Pressure Ulcers Detected by Infrared Thermography. J. Clin. Med. 2021, 10, 2883. ​ Fierheller, M.; Sibbald, R.G. A clinical investigation into the relationship between increased periwound skin temperature and local wound infection in patients with chronic leg ulcers. Adv. Ski. Wound Care 2010, 23, 369–379. ​ Bharara, M.; Schoess, J.; Nouvong, A.; Armstrong, D.G. Wound inflammatory index: A “proof of concept” study to assess wound healing trajectory. J. Diabetes Sci. Technol. 2010, 4, 773–779.