A 30 year old lady is to undergo surgery under intravenous regional anesthesia for her left ‘trigger finger’. Which one of the following should not be used for patient ?
**Core Concept**
Intravenous regional anesthesia (IVRA) involves administering a local anesthetic into a limb through a vein, isolated from the rest of the body by a tourniquet. This technique requires careful selection of patients and medications to prevent systemic toxicity.
**Why the Correct Answer is Right**
The correct answer is **lidocaine**. Lidocaine is a commonly used local anesthetic in IVRA, but it has a narrow therapeutic window and can cause systemic toxicity, including central nervous system (CNS) and cardiovascular effects, if it escapes into the systemic circulation. However, the contraindication in this scenario is more about the patient's condition rather than the anesthetic itself.
**Why Each Wrong Option is Incorrect**
**Option A:** **Bupivacaine** is actually contraindicated in IVRA due to its high potency and potential for severe cardiac toxicity, making it a safer choice is **not** correct because bupivacaine is indeed contraindicated.
**Option B:** **Ropivacaine** is a safer alternative to bupivacaine, with a lower potential for cardiac toxicity, making it a suitable choice for IVRA.
**Option C:** **Mepivacaine** is another local anesthetic that can be used in IVRA, with a lower potential for systemic toxicity compared to lidocaine.
**Option D:** **Prilocaine** is a local anesthetic that can be used in IVRA, but it has a lower potency and a higher potential for methemoglobinemia, making it less ideal.
**Clinical Pearl / High-Yield Fact**
When selecting a local anesthetic for IVRA, consider the patient's underlying medical conditions, the type of surgery, and the potential for systemic toxicity. Always choose a local anesthetic with a low potential for cardiac toxicity and a wide therapeutic window.
**Correct Answer: D. Prilocaine.**