I am currently working with my PhD research proposal focusing on developing learning strategies to improve compassionate care among undergraduate nursing students when they are caring for people at end-of-life care period.
A good scale should measure the aspects of degree of passion on care, usage of empathic verbal and nonverbal expressions, teamwork, documentation, briefing and debriefing, appreciation of any little improvements, degree of partnership with the family.
Not sure if this is useful, but NICE have started producing quality standards, and their end-of-life guidance is here http://www.nice.org.uk/guidance/qs13/chapter/list-of-statements
Although not specific to palliative care The Consultation and Relational Empathy (CARE) Measure has been used extensively in Scotland (primarily with GPs but also nursing and AHP staff) with normative data available and might be of interest to you if adapted. Here are some links
http://www.caremeasure.org/
http://www.gla.ac.uk/media/media_141446_en.pdf
You might also find Belinda Dewar and colleagues’ work on ‘Emotional Touch points’ useful.
One component of compassion and empathy (and a measure thereof) is the wants, needs, and happiness of the patient undergoing palliative or end-of-life (EoL) care. For such a patient, at the given juncture of life, anything that pleases or eases the mind may be worthwhile - notwithstanding physical effects.
The measure therefore would be how (often) happy, satisfied, and peaceful the patient is.