2016 personal communication
Response to critique on methods for studying the pressure applied by compression fabrics
Hegarty-Craver, M., Grant, E., Kravitz, S., & Reid, L. (2016, April).
MeSH headings : Compression Bandages; Humans; Leg Injuries / therapy; Pressure
TL;DR:
The authors conclude that sub-bandage pressures are not significantly affected by changes in posture, and the static stiffness index (SSI) is not clinically relevant, which dramatically conflict with recent research in this field.
(via Semantic Scholar)
UN Sustainable Development Goal Categories
3. Good Health and Well-being
(Web of Science)
Source: Web Of Science
Added: August 6, 2018
W ith great interest we read the three articles reporting on the application of analytical methods for studying the pressure applied by compression fabrics, by M. Hegarty-Craver, S. Kravitz and co-workers.1,2,3 Based on the findings of their research, the authors conclude that sub-bandage pressures are not significantly affected by changes in posture, e.g. from rest to standing, when used as intended within the therapeutic range.2 In addition they conclude that the static stiffness index (SSI) is not clinically relevant.3 These conclusions are solely based on the results of in vitro testing and mathematical equations, without any support of clinical data, which makes it difficult to understand that the clinical relevance of the SSI can be denied so easily. As both conclusions dramatically conflict with recent research in this field, and as the authors suggest, that the results from in vivo testing should be re-examined, we feel the strong need to question these conclusions. Our main criticism is related to the obscure relationship between the findings of the tensile testing device and the leg circumference measurements. The authors assume that there is a one-toone relation between the findings of their testing and conclude that activities of the lower limb cause very limited increase or decrease in subbandage pressure on different individuals. This however conflicts with long-established principles of dynamics and physics of compression therapy, which are well documented in recent literature.4–10 The first paper in this series reports the testing of the stretch profiles of bandaging systems,1 on which we neither feel the need to comment, nor to question the findings of the measurements of the leg circumference. However, in this article an equation is used that was introduced by Thomas.11 The equation P=(N*T1)/(W*R) used in this article, substantially differs from the referenced equation by using the radius (R), where Thomas uses the circumference (C) in: P=(N*T1)/ (W*C). While C=(2R*3.14), the resulting P will be very different in both equations. In the second paper of this series,2 the authors combine the stretch profiles of five compression systems, quantified with a tensile tester, with leg circumference changes in different positions measured on healthy volunteers to simulate pressure changes under applied compression. Measuring the stretch profile of compression systems is an established method for in vitro research.9 However, we question the accuracy and repeatability of their leg circumference measurements using a fabric tape measure, with which the authors were not able to find an increase in calf circumference after the change from a sitting to a standing position.12 By combining these questionable leg circumference changes in different positions with the calculated stretch profiles, the authors present pressure profiles at three leg positions that are heavily conflicting the pressure values found in clinical practice.4–8 The static stiffness index used in recent literature is defined as the difference between the pressure at rest and in stance, which routinely is measured at the B1 level.6 The authors provide calculated values between sitting and standing positions at this level. They report an average change of 2.42 in pressure of four widely used and studied multi-component products. This value is significantly different from values measured in clinical practice, where the SSI values, i.e. the difference between supine and stance, for these products generally are above.10 In addition the authors conclude that, because the values are calculated from measurements on healthy volunteers, the numbers are higher than what would occur in a real-life situation. If laboratory findings differ so dramatically from clinical data, either the clinical data or the laboratory findings can be questioned. Based on our own findings as well as on overwhelming evidence from literature, we seriously opt for the latter. We do not question the accuracy and repeatability of the findings in this paper, we question their combinability and even more, the translation to the conclusion that pressure levels do not change significantly with changes in posture. The authors question the results from current in vivo