Using time to determine CPT code

One of my doctors wants to know:
If I see a patient at a nursing home, and spend 25 minutes, most of which is spent discussing the situation with the patient's family (e.g., discussing diagnostic results, impressions, and/or recommended diagnostic studies, discussing prognosis, or discussing management/treatment plans), can I use time as a deciding factor in determining the CPT code? I know if I spent >50% of the time involved in counseling and/or coordination of care with other providers, I could use time as a factor, but is this acceptable to use time when I spend the time counseling the patient's family?

inpatient nursing home

http://www.sccma-mcms.org/_images/_userfiles/File/billingFamilyCounseling.pdf