“How long does ulnar nerve block last?”

Depends on short or long acting drug is used. From an hour to a day.

There are many factors that influence the duration of anesthesia. The first, and probably the most obvious, is that the duration of action depends on exactly which anesthetic agent was injected. Some agents are intended to provide only a short duration of anesthesia, while others provide much longer durations. But the answer becomes even more complex, as it depends on the removal of the anesthetic agent as well. Some anesthetic agents (i.e., "anesthesia drugs") are "cleared" or removed fairly rapidly from the site in which they are deposited, while others are made to resist that removal, and that resistance to removal also deals with reducing the rate of various mechanisms that would otherwise remove them fairly quickly. Specific "local" or "regional" anesthetic agents may also have other drugs added to them to retard the body's ability to remove them from the location in which they are injected, thereby prolonging the anesthetic duration. But beyond the characteristics of the drug itself, the rate of clearance of an anesthetic agent also depends to some extent on patient characteristics such as temperature, blood flow to the area in which the anesthetic was injected, etc. In summary, there is no easy answer to what appears on the surface to be an easy and straightforward question, as the true answer is "it depends.," and it depends on multiple factors which are considered by the person (physician, nurse, or other healthcare professional) administering the anesthetic agent.

Max 6-10 hours

The duration of a nerve block is dependent on which local anesthetic is used and if any adjuncts to prolong the block were used. If a short acting local anesthetic like lidocaine is used, the nerve block may only last an hour or 2. If a long acting local anesthetic like bupivacaine is used the nerve block may last 4-6 hours. If epinephrine is added to the local anesthetic it will roughly double the duration. If a medication such as dexmedetomidine or clonidine is used, the duration could be 4-8x longer.

Depending on the local anesthetic used , the pain relief could last anywhere from 4-24 hrs.

1 to 2 hours

An ulnar nerve block is usually done for surgery on your upper extremity. Depending on the anesthetic use, it can last anywhere between 30 minutes to 2 hours.