Is anything incumbent upon the trainee who injected a patient who died due to the spread of inflammation caused by the injection, knowing that the trainee performed the injection after the approval of the responsible doctor, and was not the one assigned to assess the case?

We understand from the question that the injection increased the inflammation, which led to the patient's death. The answer is summarized as follows: 1. The original principle is the absolution of liability, and it is only judged with certainty. 2. If giving the injection is not considered negligence or carelessness according to experts, then there is nothing on the doctor or nurses. However, if it was medical negligence and carelessness that led to death, then its ruling is that of accidental killing. The doctor is liable if they commit a mistake that someone like them would not commit, or if they were negligent or careless. 3. If there is liability, the original rule for liability is that liability falls on the direct actor, not the one who caused it indirectly. However, there is an exception to this if the one giving the order is in a position of compulsion over the one being ordered, such as an employee's obedience to their boss, and a doctor's authority over nurses. So, if a doctor orders a nurse to give an injection that leads to the patient's death, and the nurse was unaware of its harm, then the liability falls on the ordering doctor.

And Allah knows best.