There is a good article on engorgement in LLLs Breastfeeding
Abstracts August 1991 by Linda Shrago ( one of my heroes
or should that be heroines )
The article that may be helpful : Michlovitz, S. L. and S.L.Wolf
"Thermal Agents in Rehabilitation " Philadelphia: F A Davis Co 1986.
Ruth Bacon IBCLC Thornhill Ontario