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How nerve blocks and nerve sheath catheters work

​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​Nerve blocks and nerve sheath catheters offer a means to control post-operative pain.​

As part of the recovery following your upcoming surgery, you will use a peripheral nerve block catheter and infusion pump to help reduce pain. A nerve block can be used for surgery on the shoulder, elbow, forearm, wrist, hand, fingers, knee, leg, ankle, or foot.

This program will help you understand a nerve block, the catheter and the infusion pump.

​How it Works

A nerve block uses a local anesthetic to numb a specific area of the body to reduce and control pain following surgery.

Doctors use nerve blocks to help patients feel better faster, recover more quickly and go home sooner.

Specifically, nerve blocks:

Significantly reduce pain after surgery

Decrease the need for pain pills

Lessen side effects of oral pain medication, such as nausea, vomiting, itching, and sleepiness

Provide better rest following surgery

Allow easier participation in physical therapy, if needed, after surgery

It used to be that patients were hospitalized for as long as 5 to 6 days following major joint surgery such as a hip or an artificial knee. Now because the patients get nerve sheath catheters to deliver pain therapy for the affected areas from the joint surgery patients are being engaged in physical therapy on the first postoperative day very successfully.

A catheter connected to a small portable pump can help control your pain for up to 4 days. However the infusion may not relieve all the pain from your procedure.

You may need additional pain medication taken by mouth. Be sure to fill all prescriptions before going home after surgery. Carefully follow the directions for these oral pain medications.

After checking in for your surgery, an anesthesiologist will see you to discuss your nerve block. You will then receive medicine in your I-V to help you relax.

The procedure starts with the anesthesiologist numbing the skin with a local anesthetic. Then the anesthesiologist inserts a stimulating needle and uses a small hand-held machine called a nerve stimulator. This machine sends a low-level electrical pulse below your skin to help pinpoint the exact location of the nerve. The signal causes a painless muscle twitch and possibly a tingling sensation. The anesthesiologist may also use a small ultrasound machine.

Next, the anesthesiologist gently threads a small catheter about the size of angel hair spaghetti or a heavy piece of fishing line through the needle. The catheter stays in place and the needle is removed. A dressing covers the catheter.

Before you go home, the nurse will connect the catheter to a small pump about the size of a baby bottle. When the pump is connected, the balloon inside the pump is full of medication and the plunger is all the way to the top. As the medication infuses, the balloon inside the pump shrinks and the plunger goes down. You may not be able to see the balloon shrinking for a day or more. The pump is empty when the balloon is completely deflated and the plunger is about halfway down and resting on its shelf.

The medication in the pump will produce some numbness in the area of the body supplied by the nerves. Because of the numbness, you could injure your arm, hand, leg or foot without realizing it. You may have to wear a sling or brace, use crutches or other assistive devices while using the nerve block. Carefully protect these areas from any injury including heat, pressure, chemicals, or other objects while using the local anesthetic nerve block infusion.

The medication in the pump will also cause some muscle weakness in the arm, hand, leg, or foot. During the nerve block infusion, don't try to use the limb with the blocked nerves as you normally would. Also, you shouldn't try to bear weight on a blocked leg or use a blocked arm to support yourself.

Risks and Side Effects

There are risks and side effects associated with a continuous peripheral nerve block, but they are extremely rare. These include;

  • Bleeding
  • Heart arrhythmias
  • Injury due to weakness or numbness
  • Nerve damage
  • Seizures
  • Confusion
  • Infection
  • Drug reaction
  • Drowsiness
  • Ringing in the ears
  • Dizziness or lightheadedness
  • Low blood pressure
  • And, for arm or shoulder surgery only, a feeling like you can't take a deep breath

Catheter Care

Some things you need to know about caring for your catheter.

If your pain is not under control, check the tubing for closed clamps or kinks. Also check if there is fluid in the pump.

Keep the dressing over the catheter clean and dry. It is normal to have a small amount of clear or pink-colored drainage under the dressing. Leakage is not a concern as long as pain control is good.

Because the catheter is not stitched in place, don't change the dressing. Instead, reinforce the dressing with extra tape if necessary.

Don't take a shower or tub bath while the catheter is in place. Instead you may sponge bathe.

Follow your surgeon's activity restrictions.

Pump Care

An infusion pump infuses the nerve block medication. There are 2 sizes of pumps. The anesthesiologist will decide which is best for you based on your surgery and your needs after surgery. The pump will be set-up for you after your surgery. There is no need for you to make any adjustments and you should not try to do so.

Some things of note about your infusion pump and tubing;

Keep the hub taped to your skin.

Keep the pump within 18 inches of the catheter insertion site.

You will receive a fanny pack to hold the pump and medication for ease of carrying. Don't drop the pump and keep it out of water.

If your doctor decides that the medication infusion will be for an extended time, you might have to return for a refill.

Catheter Removal

You will remove the dressing and catheter at home. The nurse that connects your home catheter will tell you the approximate day and time the infusion will end.

To remove the catheter:

  • Gently lift the adhesive dressing covering the catheter insertion site. You may also remove any remaining tape.
  • Grasp the catheter as close as you can to where it enters the skin and gently pull it out. There should be little discomfort or resistance to the removal. A small amount of blood or fluid drainage is normal.
  • Hold pressure over the site for 5 minutes. Then apply a band-aid.
  • You may remove the band-aid later that day.
  • If you have any problems, call the phone number provided in your discharge instructions.
  • Wash the skin to remove any surgical soap or adhesive near the site.
  • Any remaining numbness you've been feeling should go away within 24 hours after the catheter is removed.
  • Discard the catheter, tubing and pump in the garbage. Do not try to remove any leftover medication. The medication does not contain any narcotic drug and is not for oral or intravenous injection. Toxic reactions could result from an intravenous injection.

After removal of the catheter, you may need to continue taking oral pain medication.

Signs and Symptoms

If you notice any of the following signs and symptoms, report them to your doctor

  • Signs of infection such as redness, tenderness, swelling, or pus-like drainage at the insertion site
  • Bleeding from the insertion site
  • Lightheadedness, dizziness, or excessive drowsiness
  • Discoloration of the hand, fingers, foot, or toes
  • Ringing in your ears
  • Numbness and tingling around your face or mouth
  • A metallic taste in your mouth
  • A significant change in pain or a change in numbness in the arm, hand, leg, or foot
  • A drug reaction such as a rash or itching
  • Numbness or tingling lasting more than 24 hours after catheter removal
  • Or pump leakage

Follow up Calls​

You will receive a phone call at home to evaluate your pain control and discuss any questions or concerns. If you have any questions or problems with the nerve block or infusion, call the phone number provided in your discharge instructions.