In conducting any investigation, inspection, or hearing under this chapter, the commissioner and his authorized representative are empowered to subpoena witnesses, compel their attendance, administer oaths to witnesses, examine witnesses under oath, and require the production of any books or papers deemed relevant to the investigation, inspection, or hearing. A subpoena issued under this section shall be regulated by the civil practice law and rules. The confidentiality of information obtained by the commissioner from patients' records shall be maintained in accordance with the provisions of this chapter.