(CR-034) Relative Pressure Drop – a new proposed measure of sustained compression

andreas Nilsson, PhD – CEO, PressCise

Introduction: Compression treatment is much more than just a single number of interface pressure. For this reason, measures as the Static Stiffness Index ought to be monitored in studies of compression products. The use of stiff systems today is well known to give a boost to the so-called ‘massaging pumping effect’, therefore improving the ejection fraction. Stiff systems are characterized by the fact that the pressure increases drastically if limb girth increases. However, the backside of the coin is that the stiffness will make the pressure drop rapidly if a limb’s girth decreases. Hence, a measure to evaluate an applied compression system should monitor the change of pressure over time. The aim in this study is therefore to evaluate Relative Pressure Drop, RPD, as a new measure of compression product performance.

Methods: The new measure was evaluated for three different compression systems: a zinc-based bandage, a four-component system and a new smart textile compression system. The zinc- and four-component system were applied by the same well-experienced individual on two healthy volunteers. The new compression system was self-applied by a third healthy volunteer. The interface pressures, P, were measured at pointsB1 and C in supine position after the application, and again after four hours. The procedure was repeated for four consecutive days.
The Relative Pressure Drop, RPD, is defined
RDP=1/P dP/dt ≈ (P(0) - P(Δt))/(PΔt)
RPD was also estimated from the fabric elasticity of the compression system applied using the chain rule from calculus.

Results: The relative pressure drop was greatest for the four-component system at (B1) followed by the zinc-system at (C). For the new system, however, the RPD was very limited, and in two cases, even zero.

Discussion: The RDP measure gave a clear view of how the pressure was maintained over time by the three systems.
In conclusion, the suggested RPD measure can, in a straight-forward way, describe pressure behavior over time for a compression product and its application.