Regional anesthesia is when only a specific area of the body needs to be anesthetized in order to perform an operation. Some types of regional anesthesia are peripheral nerve blocks, spinal anesthesia, and epidural anesthesia. Spinal and epidural blocks are frequently used in Obstetric Anesthesia.
Peripheral Nerve Blocks are performed to numb a specific limb or part of your body. It might be used to numb an arm or leg, for instance, if it's not safe for you to undergo general anesthesia. Or you and your anesthesiologist may decide that it would be better for your surgery to be done with a peripheral nerve block and sedation (see Sedation Anesthesia). Sometimes, peripheral nerve blocks are performed after surgery, to reduce the pain you'll feel and reduce the amount of pain medicine you'll need (such as a knee replacement, or a shoulder surgery). Most, but not all, areas of the body can be numbed with a nerve block to reduce pain before, during, or after surgery.
Spinal Anesthesia (also called a Sub-Arachnoid Block) involves injecting a numbing medicine (local anesthetic) into the fluid surrounding the spinal nerves. This is almost always done in the very lower part of your back. Once injected, the medicine mixes with spinal fluid in the lower back and numbs the nerves it contacts, effectively blocking sensation, pain, and movement. Spinal anesthesia takes effect rapidly (just a few minutes), and could last anywhere between 30 minutes and 4 hours. It is especially effective for some surgeries on the lower abdomen and legs (like a cesarean delivery, or a knee replacement).
Epidural Anesthesia involves the placement of a very small plastic tube (an epidural catheter) into a space in your back called the epidural space. The catheter is tiny, only a few millimeters in diameter. It is different than a spinal, however, in that the medicine is not mixed into the spinal fluid. Epidurals can be placed in your lower back, for pain in the lower part of your body (such as a cesarean section, or a knee surgery), or higher in your back for a surgery that involves your upper abdomen or chest (like a surgery on your lung). Epidural medications can be given through this catheter to provide numbness for the surgery, and can also be used to provide pain relief in the post-operative period. Epidurals are frequently left in for 3-4 days after an operation and can help patients have better pain control and fewer side effects from pain medicines (such as nausea or constipation). Epidurals can also help improve your ability to cough and breathe deeply after surgery and aid in a speedy recovery towards discharge home.