Cuff Pressure Algometry in Patients with Chronic Pain as Guidance for Circumferential Tissue Compression for Wearable Soft Exoskeletons: A Systematic Review

Abstract

In this article, we report on a systematic review of the literature on pressure-pain thresholds induced and assessed by computerized cuff pressure algometry (CPA). The motivation for this review is to provide design guidance on pressure levels for wearable soft exoskeletons and similar wearable robotics devices. In our review, we focus on CPA studies of patients who are candidates for wearable soft exoskeletons, as pain-related physiological mechanisms reportedly differ significantly between healthy subjects and patients with chronic pain. The results indicate that circumferential limb compression in patients most likely becomes painful at ∼10-18 kPa and can become unbearable even below 25 kPa. The corresponding ranges for healthy control subjects are 20-42 kPa (painful limits) and 34-84 kPa (unbearable levels). In addition, the increase of pain with time tends to be significantly higher, and the adaptation to pain significantly lower, than in healthy subjects. The results of this review provide guidance to designers of wearable robotics for populations with chronic pain regarding rates and magnitudes of tissue compression that may be unacceptable to users.

Discomfort/Pain and Tissue Oxygenation at the Lower Limb During Circumferential Compression: Application to Soft Exoskeleton Design

“…Hence, our aim was to gain insight into the prepain phase of discomfort. According to this, we have proposed in our previous review paper (Kermavnar et al, 2018b) that a modified version of the cuff algometer be used to assess discomfort rather than pain.…”

Soft Robotic Suits: State of the Art, Core Technologies, and Open Challenges

“…A recent meta-analysis on cuff pressure algometry [121] suggests that exposure to "circumferential compression leads to discomfort at approximately 16-34 kPa, becomes painful at approximately 20-27 kPa, and can become unbearable even below 40 kPa". These limits are much lower, however, in people with chronic pain, indicating the need for much more stringent requirements for soft robotic suits in the healthcare domain: the threshold for pain is between 10 and 18 kPa, and pressures can be unbearable even below 25 kPa [121].…”

Safety Assessment of Rehabilitation Robots: A Review Identifying Safety Skills and Current Knowledge Gaps

“…More specifically, a systematic review found pain detection thresholds in healthy persons (i.e., pain onset thresholds; perceived discomfort) for circumferential pressure of between 16 and 34 kPa and pain tolerance thresholds (i.e., the pain becomes unbearable) of 42-91 kPa (Kermavnar et al, 2018b). Another systematic review states that circumferential pressure limit values for chronic pain patients are significantly lower, with pain onset thresholds of about 10-18 kPa and pain tolerance thresholds of below 25 kPa (Kermavnar et al, 2018a).…”

“…Most studies investigating pain pressure thresholds have been performed with healthy individuals. However, the systematic review mentioned above (Kermavnar et al, 2018a) identified that pain perception differs significantly between healthy individuals and patients with chronic pain. Moreover, the reaction to contact pressure is highly dependent on factors such as the anatomical structure, tissue composition and stiffness, blood flow, lymphatic flow as well as the individual health status and diseases affecting inflammation and repair capacities (Bader et al, 2019).…”