Final answer:
The nurse should check the client's record for a signed informed consent prior to initiating the blood transfusion for a client with esophageal bleeding.
Step-by-step explanation:
Prior to initiating the blood transfusion for a client with esophageal bleeding, the nurse should check the client's record for a signed informed consent. This ensures that the client has provided consent for the procedure and is aware of the potential risks and benefits. Informed consent is an important client safety action to protect the client's autonomy and rights. Other actions mentioned in the options, such as running the blood warmer, ensuring the client has a 22-gauge intravenous catheter, and priming the administration set with normal saline, may also be necessary steps in the blood transfusion process, but checking for a signed informed consent is the first safety action that should be performed.