Three years after the death of her father in an ICU, the infection prevention nurse was visiting an ICU in a different hospital to complete a chart review. At one point, the nurse looked at a bed containing a client with the same diagnosis as her father. The nurse saw her father's facial features on the client and experienced a sense of panic. In a few moments, the nurse realized that the client in the bed was not her father. What manifestation of posttraumatic stress disorder (PTSD) was the nurse experiencing?