Self-care deficit theory teaches that people benefit from nursing because they have health-related limitations in providing self-care. Limitations may result from illness, injury, or from the effects of medical tests or treatments. Two variables affect these deficits: self care agency (ability) and therapeutic self-care demands (the measures of care required to meet existing requisites). Self-care deficit results when self-care agency is not adequate to meet the known self-care demand.
taken from http://dana.ucc.nau.edu/~jmg8/centra...the_theory.htm
Though we did holistic theory, I think this is pretty easy to understand. For instance: normally, I would walk to the bathroom. But a broken leg would cause a deficit in my ability to walk to the bathroom. Therefore, I would qualify as needing nursing assistance to eliminate bodily waste, or bathe, or walk.
Seems like this theory is based on the normally-functioning adult model, so that means that anyone who is not a normally-functioning adult (i.e., babies, elderly, handicapped) would require some sort of compensation for their deficits.
So I would envision the image of a functional adult, and then compare that to your patient's image.
Hope that helps