Peripheral Nerve Blocks-Q&A
For total or partial knee replacements, the anesthesiologist will offer you a peripheral nerve block. The following is some basic information about peripheral nerve blocks, risks and benefits, and what to expect on the day of surgery.
What is a peripheral nerve block?
A peripheral nerve block is a blockage of pain signals from a nerve to the brain, creating a numb area. This is accomplished by surrounding the nerve with a local anesthetic. A commonly used local anesthetic is called bupivacaine.
How is a peripheral nerve block performed?
The anesthesiologist will identify the nerve using ultrasound, then clean off your skin with sterile solution. A small amount of local anesthetic is injected to numb the skin, and a needle is guided under ultrasound to a location near but not touching the nerve. The local anesthetic is then injected near the nerve.
How long will it take to get numb?
About 20 minutes.
How long with the nerve be numb?
It depends. If a single injection of local anesthetic is performed, you will be numb for 8-12 hours. If a nerve catheter is places, you will be numb for 2 days. For a total or partial knee replacement, a catheter is usually placed.
What's a nerve catheter?
A nerve catheter is a thin piece of flexible plastic tubing that is placed under the skin near the nerve. It is fastened to the skin with a bandage and connected to a plastic pump about the size of a baby bottle. The pump will inject local anesthetic for about two days.
How do I take care of a nerve catheter?
Just don’t pull the bandage off! When it’s time to remove the nerve catheter (you’ll know it’s time because the balloon inside the bottle will be empty), remove the bandage and the catheter. If the catheter doesn’t come out easily, come back to the hospital and we will remove it for you.
What are the side effects of a peripheral nerve block?
Your leg will be numb and weak. If you’re able to walk on your operative leg after surgery, you must be very careful to do so with help while the nerve block is in place. Please be aware of where your leg is at all times, as your leg could be injured without your knowledge (by stubbing your toe, for example).
What are the risks associated with a peripheral nerve block?
The three major risks of a nerve block are infection, bleeding, and nerve damage. These are all extremely rare complications. However, if you already have numbness or tingling in your leg or foot, please let the anesthesiologist know. A nerve block may be more likely to cause nerve damage if you already have these symptoms.
A peripheral nerve block will not provide all of the pain relief needed in the first two days after your surgery, and sometimes the peripheral nerve block doesn’t work at all and has to be redone.
What are the benefits associated with a peripheral nerve block?
A peripheral nerve block provides superior pain relief to oral or intravenous pain medicines alone. We find that adding a peripheral nerve block to the oral or intravenous pain medicines allows people to participate in physical therapy better and that they need less of the morphine-type pain medicines. Since the morphine-type pain medicines can make you groggy, nauseated, constipated, and itchy, we think needing less of them is better.
Do I still need to go to sleep for my surgery?
The peripheral nerve blocks does not provide enough pain relief to have surgery. You will need to either go to sleep (general anesthesia) or to have a spinal anesthetic, which will make you numb for about three hours from the chest to your feet.
If you have any questions or concerns regarding a peripheral nerve block, please email our acute pain specialist at: pain_fellow@abl.med.utah.edu.
