Skin Temperature Response to Prolonged Cooling With an Electronic Continuous Cold-flow Cryocompression Device: a Safety and Feasibility Pilot

Introduction Despite the advancement in technology for cryocompression therapy in rehabilitation after knee surgery, guide-lines for the duration of cryocompression treatments, remain largely unchanged at typically 15-30 minutes in length (Long and Jutte, 2020). This duration was originally established with the traditional use of ice packs, which provide rapid cooling and must be limited to this relatively short time period to reduce the likelihood of cold-related complications or injury (MacAuley, 2001; Wilke and Weiner, 2003; Thienpont, 2014). Electronic devices have been shown to reduce tissue temperature more gradually, and to provide an effective dose of cold without lowering tissue temperature to potentially unsafe levels (Belsey, Reid, et al., 2024). Consequently, the traditional treatment duration guidelines may not be relevant for electronic devices.

Prolonged cooling durations are more likely to effect pain and inflammation around deeper tissues (Long and Jutte, 2020), which could lead to improvements in post-operative clinical outcomes. Exposure to cold of 15 ℃ using a non-electronic technology for up to 6 hours has previously been demonstrated as safe (Kwiecien, McHugh and Howatson, 2020). One study investigated prolonged cooling (3 hours per treatment) with an elec-tronic device following knee surgery and although no complications were reported, skin temperature response was not measured. Therefore, despite safety being indicated, it is not known whether an optimal dose of cooling was applied that reduced skin temperature to within an established optimal therapeutic zone of 10-15 ℃ (Wilke and Weiner, 2003; Bleakley and Hopkins, 2010).

The safety and feasibility of prolonged exposure to cryocompression with an electronic device that is known to provide an effective dose of cold has not explicitly been examined, and should be established if traditional treat-ment duration guidelines are to be challenged, amended, and optimised for this therapy modality. Therefore, the aim of this study is to investigate the ability of an electronic cryocompression device to maintain skin tempera-ture within the target therapeutic zone for a prolonged period, and to assess the safety and feasibility of such a treatment protocol. The results from this exploratory pilot study can then be used for future research into the efficacy of prolonged cooling in clinical settings and investigations into optimal treatment duration depending on the therapy modality employed.

It is hypothesised that an electronic cryocompression device will successfully reduce skin temperature will be re-duced and maintained within the 10-15 ℃ target range during a prolonged treatment. Secondly, it is predicted that there will be no treatment-related adverse events and the protocol will be well tolerated by participants in terms of perceived comfort.

Methods Design This prospective randomised controlled crossover trial will recruit healthy adult volunteers from a university population to participate, in line with previously published recommendations for appropriate sample sizes for pilot studies (Julious, 2005; Johanson and Brooks, 2010). Each participant will take part in each of the two conditions in order to eliminate the risk of demographic factors confounding the results. Conditions will be conducted in a random order, as determined by a random number generator before recruitment begins. Conditions will involve the application of a Physiolab S1 cryocompression device in accordance with the manufacturers' guidelines. Each testing session will take around 3 hours to complete, with at least 24 hours between tests with the same participant. In total, participants will be giving no more than 6 hours of time across 2 days to complete their participation. Participants will not be compensated for taking part in the study, nor will they be charged.