Immersion: Degrees of Difference with Positional Changes

Introduction and Purpose:

Immersion testing was developed by the NPUAP’s Support Surface Standards Initiative (S3I) to help quantify and compare pressure redistributing properties of different therapeutic support surfaces (TSS). It compares surfaces by measuring the depth at which the surface allows a person to sink or immerse. This in turn gives information about the amount of contact surface area and the amount of pressure that has the potential to be redistributed.

However, standardized immersion testing to date has only been tested in the supine position with the NPUAP rigid 50^thpercentile male test indenter mannequin. This poses a problem as most patients do not remain in the supine position for the majority of the day; instead, they are usually positioned at an angle. When a patient moves or shifts to a different position, can it be assumed that immersion would shift as well. Can the current immersion test methods meet this requirement?

Methodology:

Immersion testing was completed on a therapeutic air support surface according to the proposed standardized immersion test. The surface was tested at the supine, 45 degree head of bed, and fully seated positions.

Results:

The supine mannequin was unable to be used for the other positions so a hinged mannequin was used in its place for the other two positions. The surface yielded the following results: 38% immersion in the supine position, 35% immersion at a 45 degree head of bed elevation position and 39% immersion for a fully seated position.

Conclusion:

Due to the design of the mannequin, immersion was unable to be measured with the standard mannequin in the 45 degree and seated positions. Modifications to the testing standards and/or the mannequin were needed. Additional testing and research based on body position on a standardized, hinged mannequin may be desirable.