Characterizing the Relationship between Pressure Loading and Skin Temperature in Pressure Ulcer Risk Patients

Background: Pressure ulcers (PUs) are defined as an area of localized damage to the skin and underlying tissue caused primarily by sustained pressure loading. PUs are a widespread problem that poses a tremendous burden to the healthcare system and the quality of life of the affected individuals. Objectives: This thesis characterized the relationship between skin temperature and pressure in patients with high PU risk by analyzing how the skin temperature reacted to notable pressure changes and different types of pressure loadings. In addition, we investigated whether different preconditions, that are related to PU formation, affected a patient's skin temperature. Methods: We used a medical wearable to continuously monitor skin temperature and pressure in 60 hospital patients at high risk of developing PUs. to locate pressure loadings in the recorded time series, we evaluated different peak detection algorithms. The pressure loadings were further subdivided using k-means clustering. To analyze the skin temperature reaction to the identified pressure loadings, we used spike-triggered averaging (STA). Additionally, we explored the potential of artificial neural networks to predict pressure sensor curves solely based on skin temperature measurements. Results: We recorded a total of 285 days, 14 hours and 12 minutes of skin temperature measurements from which we extracted 870 individual pressure events. The STA analysis revealed a strong positive correlation between pressure and skin temperature. The rise in skin temperature was proportional to the duration of the pressure loading. Patients with a previous history of PU development seemed to have changed their position less frequently compared to patients without PU history. They also showed a significantly lower average skin temperature, compared to patients without preconditions. Conclusions: A significant rise in skin temperature within a short timeframe indicates increased pressure loading on the skin and could serve as a predictor for PU development. Furthermore, a low average skin temperature could be linked to a previous history of PU formation, which is why we suspect that low skin temperature may be a risk factor for PU development.