Final answer:
For long duration spinal anesthesia, Bupivacaine and Ropivacaine are the agents commonly used due to their extended period of action, whereas Lidocaine and Procaine have shorter durations.
Step-by-step explanation:
The agents used for long duration spinal anesthesia include Bupivacaine and Ropivacaine. These are both local anesthetics capable of producing anesthesia for several hours and are often preferred for procedures requiring extended periods of anesthesia. Lidocaine, while also a local anesthetic, typically has a shorter duration of action and is commonly used for shorter procedures. Procaine, known commercially as Novocain, is also a local anesthetic but is less potent and shorter in duration compared to bupivacaine and ropivacaine. Therefore, for long-lasting spinal anesthesia, bupivacaine or ropivacaine would be the agents of choice.