Wound Photography: Tracking Healing Progress

Introduction

Wound tracking refers to the ongoing monitoring and documentation of the progression and healing status of a wound over time. To track a wound, healthcare practitioners use various tools such as photography and measurement methods depending on the severity of the wound. Measuring a wound will provide healthcare professionals with valuable insights into the extent of tissue damage and will facilitate the monitoring of the healing process. It establishes a starting point for information and aids in monitoring treatment progress, thereby assisting in the evaluation and forecasting of treatment effectiveness.¹

It is believed that between 1.5 to 2 million individuals in Europe experience acute or chronic wounds, and approximately 6.5 million people in the United States have chronic wounds that are highly vulnerable to infection. Wounds have various origins; they can be due to surgical procedures or injuries, or they can be due to conditions such as vascular disease or diabetes. Regardless of their origin, wounds have a considerable but often overlooked impact on individuals and the healthcare system. The cost of chronic wounds is estimated to be more than 2.3 billion pounds every year in the United Kingdom.²  In fact, the phenomenon of wounds has been referred to as the 'Silent Epidemic.^1,3

In this article, we will go through the different wound Measurement techniques, the analysis and tracking of the wounds and finally, the future trends and advancements in wound tracking.

Why is it important to track wounds?

The main advantage of wound photography is that it offers a visual representation that surpasses what can be retained in memory or conveyed through written descriptions. Wound photography serves as a universally comprehensible means of communication that can effectively convey information to all parties involved in care, including patients, their families, healthcare providers, and the organizations supporting treatment. By incorporating wound visuals along with the bedside evaluation and the data acquired about wound History, Anatomy, Tissue properties, and Touch/visual details (referred to as HATT), healthcare professionals can utilize evidence-based algorithms to categorize wounds.^1,4

Importance of early detection of complications

Another key advantage of wound tracking is that images also serve as a chronological record, allowing for the tracking of the wound's progress over time. In fact, a crucial aspect of wound care is the importance of early detection of complications so that healthcare professionals can localize the infection or complications and potentially change treatment strategies. If a wound is undergoing a slower healing process, there is a need to reassess the existing wound healing approach. Being able to identify ulcers that are likely to remain unhealed for up to 2 to 4 weeks enables the healthcare provider to consider alternative and potentially more intensive treatment approaches.¹

How do wounds heal?

The process of wound healing involves the restoration of tissue. New cells and tissues replace dead cells and damaged extracellular matrix (ECM). However, the difficult construction process results in the loss of the tissue's original functionality. The more a wound heals, the more the wound area and depth diminish as new tissue gradually forms to close the wound.²

The different wound measurement tools

We can separate wound measurement methods into two categories: the contact and non-contact methods. The frequently employed techniques are the Ruler method, Graph method, Computerized planimetry, Digital planimetry, and the acetate method.¹

The ruler method

The ruler method, which involves measuring the wound by placing a disposable paper L-shaped ruler or a straight ruler next to the wound, is the most common approach for wound measurement. However, findings from multiple studies indicate that employing a ruler to measure the length and width of a wound and then multiplying these measurements result in area measurements that are larger than the real area, particularly for irregular wounds. A study by Shetty et al. showed that the ruler method was inaccurate with an overestimation of the wound size of nearly 50%.^1,5

The graph method

The graph method is a technique where the wound area is measured using a grid. This method involves marking the wound's outline on graph paper and then counting the squares within the traced area to calculate the wound's size in square units. The graph method for wound measurement is accurate, but it is labour-intensive and not suitable for everyday use. Because it is a contact-based wound measurement method, it also carries the risk of contamination.⁵

Limitations of the graph and the ruler method

Both the graph method and the ruler method have an additional drawback, which is the formation of epithelium within a wound, which can’t be documented through a measurement of linear dimensions.⁵ 

The acetate method 

The acetate method consists of placing a dual-layer transparent acetate material over the wound and outlining its outer edge. After this step, the bottom layer of acetate is discarded, while the upper layer featuring preprinted squares is utilized for determining the wound's area.⁵

Digital planimetry

In digital planimetry, acetate is also used to trace the wound’s perimeter. This traced wound border is then transferred onto a tablet, where the device automatically computes the wound area. Although digital planimetry is more precise than ruler measurements, it is important to note that measurement inaccuracies also arise when using the acetate technique. This is especially true when acetate is applied to a curved surface to delineate the outline and is subsequently flattened to determine the area.⁵

Electronic wound measuring tools 

Electronic wound measuring devices encompass three categories:

1. 2D devices utilize multiple point light sources with known geometry to gauge the distance between the wound and the measuring device.
2. Digital planimetry applications establish the wound's scale by placing a target next to it and employing digital planimetry techniques.
3. 3D wound measurement and imaging devices employ structured light to meticulously measure the surface of the wound bed. By using a 3D wound measurement tool, it is easier to capture the entire wound while considering the curvature of the human body.⁵

Why does the wound measurement tool matter?

A study by Frampton and Nixon showed that accurate wound assessment depends on the precision of the measurement method employed. To effectively categorize wounds as "likely healers" or "likely non-healers" at the 4-week mark, it is imperative to uphold a level of precision of 95% or higher. The measurement method employed has an impact in shaping the correct treatment for patients.⁶

What are we analysing when tracking wounds?

When analysing wounds, healthcare professionals need to record information, including the precise location of the wound, the depth, odour, the condition of the surrounding tissues, the presence of necrotic tissue (dead tissue) and exudate (fluid drainage), and any signs of infection. During wound healing, three primary tissue types emerge granulation, necrotic, and epithelial tissue.⁷ All this information will allow the medical team to assess if the wound is healing as it should be or if it needs an alternative solution.

Obtaining informed consent and preserving patient privacy

When using digital wound photography, patient consent and privacy are the priority. In fact, healthcare professionals need to use encrypted hospital-owned mobile phones or cameras. Digital wound photographs must then be securely uploaded to safe platforms to preserve patient’s privacy.  Before obtaining consent for digital wound photography, it is imperative to transparently explain to the patient the purpose of these photographs and any potential future applications.⁸

Risk management

It is important to implement measures aimed at minimizing the potential for cross-infection resulting from the use of digital wound photography devices. One such precaution involves the regular use of detergent wipes to clean the equipment after each use.⁸

Future advancement

This year, a new research study by Chairat et al., showed the effectiveness of using an Artificial Intelligence assisted wound assessment tool to effectively track wounds. The algorithm created could calculate the wound area, necrotic tissue, granulation tissue and epithelialization area from wound photography taken with a mobile phone. A calibration chart was created, and automatic algorithms were created to make colour and measurement calibration. The study showed that using artificial intelligence for automatic length, width, and wound area measurements helped with the issue of overestimation found in conventional wound measurement techniques. Similarly, colour calibration of wound images helped rectify the differences between lightning conditions when taking a photograph by unifying the colour shades. This new research shows that using artificial intelligence for the automated measurement of wound areas offers clinicians the ability to monitor wound healing progress remotely, thereby reducing the required time and effort while simultaneously enhancing the efficiency of wound care.

Future work could focus on the creation of a portable device with all the AI algorithms for wound evaluation, enabling medical professionals to track wounds conveniently and precisely across diverse settings. This innovation especially holds promise in remote regions with restricted availability of specialized wound care facilities.²

Conclusion

In conclusion, wound tracking plays a pivotal role in facilitating the ongoing assessment and documentation of wound progression and healing status. Healthcare practitioners employ various tools and measurement methods to gain insights into wound characteristics, tissue damage extent, and treatment progress. Accurate wound assessment is crucial, given the significant impact of wounds on individuals and healthcare systems.

Timely detection of complications through wound tracking can lead to alternative treatment strategies and improved outcomes. Wound measurement tools, both contact-based, like the ruler and graph methods and non-contact tools, like 2D and 3D devices, offer distinct advantages and limitations.

Recent advancements in AI-assisted wound assessment demonstrate the potential to revolutionize wound tracking, offering automated and more accurate measurements. These innovations are particularly promising for remote and underserved areas with limited access to specialized wound care facilities.

As the field of wound tracking continues to evolve, future work may involve the development of portable devices equipped with AI algorithms, enabling healthcare professionals to track wounds conveniently and precisely in diverse settings. These advancements hold the promise of improving wound care outcomes and reducing the burden on both patients and healthcare systems.