Variability of interface pressure produced by ready-to-wear compression stockings

To assess the variability of interface pressure and changes in this pressure over one month time interval under ready-to-use compression stockings.

Fifteen healthy volunteers with a broad range of sizes and shapes of the calves were included in final analysis. Each volunteer sequentially used six pairs of stockings daily for one month each. The six pair set consisted of stockings of three compression classes (class 1: 20-30 mmHg, class 2: 30-40 mmHg and class 3: 40-50 mmHg), made of two materials with different stiffnesses. Interface pressure measurements were performed at B1 point using SIGaT(®) tester (Ganzoni-Sigvaris, St Gallen, Switzerland). Interface pressure was measured in supine and standing positions, and during performing 10 tiptoes. Pressure measurements were performed twice (in the morning and after using stockings for eight hours) on the first day of using each pair of stockings, and repeated on the 30th day.

At the time of the first use the interface pressure was within the range specified by the manufacturer for 160 out of 180 individual stockings. Twenty stockings (11.1%) produced interface pressure which was 5 mmHg or more outside the range of specified compression class. In 16 of these cases it was only one of the pair of stockings from the same box that produced lower than specified pressure. The pressure under stockings did not change significantly during the day. After one month the interface pressure under the class 1 stockings decreased on average by 1.4 ± 4.3 mmHg (P = 0.013). Class 2 and 3 stockings showed minimal pressure changes which were not statistically significant.

In vivo measurements of interface pressure should be a requirement for clinical studies of compression stockings, and may be reasonable for ensuring appropriate pressure level in clinical practice.