What effect can epinephrine have when added to local anesthetics?

When epinephrine is added to local anesthetics, it serves several important functions, one of which is to prolong the duration of anesthesia. This occurs due to epinephrine's vasoconstrictive properties. By constricting blood vessels at the site of injection, epinephrine reduces blood flow, which consequently decreases the rate at which the local anesthetic is carried away from the site into systemic circulation. This localized action allows the anesthetic to remain in the tissues longer, enhancing its effectiveness and extending the period during which the patient remains anesthetized.

This prolongation of effective anesthesia is particularly beneficial in procedures that require extended surgical time, as it allows for longer pain relief with a single administration of the local anesthetic. The combination of local anesthetics with epinephrine is a common practice in various types of surgical procedures, facilitating better patient outcomes with prolonged pain control.