In addition to these publications specifically about healthcare, see the journals on the Commercial Design tab.
The Trustee Library provides access to many different collections of articles and is an excellent tool for academic research. Some of the best collections of healthcare articles, including some on design, are listed and linked below.
"time spa" AND design
spa AND design
wellness AND "interior design"
"health resorts"
"health facility environment"
"health care design"
"health promotion"
"health facilities"