Impact of Casting and Splinting Manipulations on Below-Dressing Pressures: An Experimental Model

Abstract

Background: We tested how different applications of casts and splints affect underlying below-dressing pressures and how these dressings respond to swelling. Methods: A 3-in polyvinyl chloride pipe with an attached 100 mL saline bag to the outer surface was used to simulate a human forearm. A pressure transducer was attached to the bag and connected to a monitor providing continuous pressure measurements. Either a circumferential fiberglass cast or single-sided plaster splint was applied around the bag. To simulate the dressing’s compliance to soft tissue swelling, change in pressure was measured after 25 mL of saline was injected into the bag. Compliance was determined by calculating change in volume over change in pressure as volume was added. Results: In our 150 mL model, cast bivalving reduced pressure up to 28%, and splitting the cotton padding of a splint reduced pressures up to 33%. The mean compliance (ability to accommodate swelling) across all volume intervals was 182% greater in a bivalved cast versus a cast and 21% greater in a cotton-split splint versus a splint. Below-dressing pressure of a tightly wrapped elastic bandage was up to 2.76× greater than a medium tension bandage and up to 6.44× greater than a loosely applied bandage. A splint with real cotton padding had a 28% greater pressure than a splint with synthetic soft-roll padding. Conclusions: Splitting a dressing, utilizing synthetic cotton padding, and applying an elastic bandage cautiously can help reduce surface pressures and allow the construct to be more accommodating to soft tissue swelling.