JB, what you mention seems to be more of a neuro assessment of whether or not the patient is able to respond
to pain. When dealing with comfort care, it seems to me borderline unethical to cause
pain during an assessment.
When I have a patient on "comfort care", I use several assessments. The first is how the patient reacts during cares and turns. Moans, cries, or grimaces are all indications for increased medication. Vitals are a second assessment (increased heart rate, BP, or respirations), however "normal" vitals do not contraindicate medicating for pain. Families are a good source as well. Sure, we sometimes get annoyed by them, and they sometimes over-react, but they generally have a good idea when a family member is in pain and might need more medication.
Let's not forget complimentary therapies as well. Backrubs, fans, and gentle conversation might help. I find light aromatherapy very effective (the scent of benzoin is very calming). Music therapy can help too (be sure to ask what the patient
likes to listen to -- don't assume
!) All of these things can help ease pain. Not that you want to abandon the medication, but complimentary therapies may allow you to use less
medication to maintain the same amount of analgesia.