A Registered Respiratory Therapist (RRT) is a health care professional who utilizes the concepts of respiratory care in the management of patients with suspected or known chronic or acute lung disorders and disorders requiring oxygen supplementation. RRTs perform various diagnostic procedures to determine the cardiopulmonary care needs which are performed on the orders of the primary care or specialist physician. Applicants pending the completion of educational or certification/licensure requirements may be referred and tentatively selected but may not be hired until all requirements are met. Citizenship. Citizen of the United States (U.S.). Non-citizens may be appointed when it is not possible to recruit qualified citizens in accordance with chapter 3, section A, paragraph 3g, of this par