Imaging tissues for pressure ulcer prevention

Abstract

Every day, clinicians determine tissue status by visual and physical assessment. These practices, although technologically simple, belie the complex range of physiological responses of the tissues that may be detected by clinical assessment. Observations made by clinicians are used to assess the integrity of tissues and their response to the mechanical, physical and chemical environment. Clinical observation, however, is limited in a number of important ways. Qualitative clinical assessment is difficult to record accurately, particularly when observations require recording of subtly different levels in tissue status or response. Different observers also often record qualitative observations differently. This often results in difficulties when working in teams or shifts, or when information is assessed over time. Imaging often requires qualitative interpretation of the information recorded, but the image at least captures information in a way that allows multiple assessors to view the same primary dataset. However, the nature of imaging systems in healthcare settings usually requires them to be operated by clinical and technical specialists working in a dedicated setting. They are usually used for diagnosis and screening in order to detect early evidence of pathologies, or to assist in the provision of interventions, such as surgery or radiotherapy. The potential for using imaging systems for the prevention and management of pressure ulcers is an altogether different proposition. With the prevalence of pressure ulcers in district general hospitals reported to be between 15 and 20% [ii, use of specialist imaging facilities to assess wound status, or to identify particularly vulnerable patients, would create an overwhelming demand for scarce resources. Practical imaging systems to assist in pressure ulcer management must therefore be simple enough to use at the bedside. It may also be desirable for these systems to make measurements of parameters associated with the interaction of the patient with the bed or seating system, as it is here that problems with tissue integrity first occur. The cost of managing and preventing pressure ulcers certainly could justify the use of quantitative methods for tissue risk assessment and for monitoring the healing of ulcers. At present, however, confidence in the value of these technologies is modulated by their complexity, their cost and the lack of evidence of their efficacy. From the technology developers perspective most of the technical requirements for instruments to provide reliable measurements of physiological or mechanical parameters can be fulfilled. However, a significant barrier to their development is the lack of sound physiological and aetiological understanding of pressure ulcer pathology, as highlighted in Chap. 1. Without a direct link to validated aetiological models, the design of effective clinical tools cannot be accomplished with confidence. For this reason many of the tools in use clinically have their origins as research instruments to measure specific physiological or mechanical parameters. They are most effectively used by clinicians, who use the information provided by these instruments to supplement their clinical skills and intuition. Much can, however, be learnt from work to date, from technologies developed for related application areas and from the use of instruments by researchers seeking to develop an improved understanding of the pressure ulcer problem. This chapter reviews many of these technologies and the insight they can provide into pressure ulcer aetiology.