Medical fluid injection apparatus and method with detachable patch and monitoring

A method for measuring a health or physiological parameter from a subject, comprising:

• (a) providing (i) a patch comprising a first housing comprising a sensor, and (ii) an injector comprising a second housing, wherein said second housing encases a cannula, a fluid flow path, and a reservoir comprising a substance, wherein said cannula is in fluid communication with said fluid flow path, and wherein said fluid flow path is in fluid communication with said reservoir, wherein said first housing and said second housing are in a locked configuration such that said patch remains attached to said injector;
• (b) securing said patch to a body of said subject;
• (c) with said patch secured to said body of said subject, directing said cannula through an opening and into said body of said subject;
• (d) subsequent to (c), (i) directing said substance from said reservoir to said fluid flow path, and (ii) directing said substance from said fluid flow path into said subject through said cannula, wherein subsequent to directing said substance into said subject, said first housing and said second housing are in an unlocked configuration such that said injector is removable from said patch;
• (e) removing said injector from said patch to leave said patch secured to said body of said subject;
• and
• (f) subsequent to (e), using said sensor to (i) measure said health or physiological parameter from said subject, and (ii) provide one or more outputs corresponding to said health or physiological parameter from said subject.