Interface Pressure Behavior During Painful Cuff Algometry.

Abstract

Cuff algometry is used for the psychophysical assessment of deep-tissue pain sensitivity. The cuff pressure homogeneity may affect the pain sensitivity assessment and potentially be improved by alternative cuff designs optimizing the pressure distribution. The aim of this study was to investigate the relationship between pain sensitivity, inflation pressure, and distribution of interface pressure between the skin and cuff during stimulation with a conventional air tourniquet and a novel tourniquet including a water tube interfacing the air cuff with the skin. Air and water cuff stimulations were applied separately on the right lower leg of 12 subjects until the tolerance pain threshold. The inflation pressure was controlled and recorded by a computer-control program, while the interface pressure distribution was measured by a flexible pressure sensor mat located between the cuff and skin. The mean interface pressure across the entire stimulation surface was not significantly different from inflating pressure during air-cuff algometry. For the water cuff there was a significant reduction in the mean interface pressure compared with the inflating pressure at both the detection and tolerance pain levels (P < 0.002). The interface pressure distribution of the water cuff around the limb was significantly more homogeneous compared with the air cuff (P < 0.03). This homogeneity showed a significant correlation with pain sensitivity (P < 0.008). Cuff systems with a liquid medium optimize the homogeneity of the interface pressure distribution. However, the deviation of the interface pressure from the inflating pressure is crucial as it counteracts the effects of pressure homogeneity on pain sensitivity in water-cuff algometry.