Degassing

Removing air from the medium is necessary to prevent air bubbles from interfering in ultrasound images and changing conductivity readings. Degassing was attempted by mechanical and chemical means. A vacuum chamber was used to try degassing several jars of viscous gel, which proved to be ineffective. A chemical degassing agent and high processing temperature were found to be most effective.

Increased Viscosity

High viscosity is helpful to achieve greater resistance to air when the gel is swallowed. This was accomplished by using a gelling agent to thicken the solution, and a viscometer was used to ensure that the production procedure resulted in a standardized viscosity.

Flavoring

Because the strong, unpleasant taste of saline is known to cause some patients to regurgitate during testing, flavoring was added to the new challenge medium to help conceal the taste of salty electrolytes. A lemon flavoring was chosen for its ability to effectively cover the taste of salt while also being economically viable, as opposed to children's medicinal flavoring.