I would advise talking to the admissions department at the school because I know a lot of places do not consider volunteering as patient care experience.
Direct patient care experience: This experience varies and can be acquired on a full or part-time basis. Direct patient care experience requiring certification and providing monetary compensation is most competitive (e.g., CNA, EMT, Patient Care Technician, etc.). Shadowing a PA is important and can enhance your application, however shadowing is not considered health care experience. Also, clinical hours obtained while fulfilling the required components of an educational program do not count towards healthcare experience. Volunteer hours are not considered competitive health care experience. An applicant needs to have acquired a minimum of 500 hours of direct patient care experience at the time of application. The admissions committee is able to consider only the hours that are complete at the time the CASPA application is submitted.