Final answer:
Gregorio's role in working closely with nurses to maintain patient safety and reporting on health changes suggests that he is a Certified Nursing Assistant (CNA), who operates under the direct supervision of a registered nurse.
Step-by-step explanation:
Gregorio works closely with registered nurses to provide a safe environment for patients and alerts them to changes in a patient’s health. Given the description, Gregorio is likely a Certified Nursing Assistant (CNA). CNAs work under the direct supervision of a registered nurse or a licensed practical nurse and focus on assisting with the healthcare needs of patients. They may help with tasks such as taking and reporting vital signs, preparing equipment, and ensuring procedures are carried out accurately and with sterility. Although a Patient Care Technician (PCT) may also perform similar functions, PCTs often have additional training to carry out specific tasks like providing dialysis treatments. With the specific detail of ensuring a safe environment and alerting nurses to health changes, the role of a CNA fits Gregorio's job description most closely.