Depending on the state of the wound, negative pressure wound therapy（NPWT）requires the use of foam dressings shaped into rectangular columns, similar to those used in the bridging technique; however, pressure delivery in this method has not been reported. We investigated the effects of the cross-sectional surface area and length of narrow, rectangular columnar foam dressings on the set pressure, and the deviance in measured values. We created 10 rectangular foam samples for each of the following groups of cross-sectional side lengths: group A）3.0 × 3.2 cm; group B）1.5 × 3.2 cm; group C）1.5 × 1.6 cm; and group D）0.75 × 0.75 cm. Using an initial set length of 200 cm, we examined the pressure delivery to the depth of the foam while shortening the length by 10 cm. By simple linear regression analysis, no significant difference in pressure delivery was found among the four groups. The set pressure may be maintained when a rectangular columnar foam dressing is used within the scope of clinical practice.