Patient Information Sheet – Guanethidine Blocks
What is Guanethidine?
Guanethidine is a drug, which has a specific effect on the sympathetic nerves and is normally used to control blood pressure.
Over years, guanethidine has also been effectively used to treat chronic pain, with a few risks or side effects involved.
When is a Guanethidine Block given?
A Guanethidine Block is used for treatment of pain conditions, which are confined to a limb. It is a method of temporarily blocking the nerves, especially the sympathetic nerves to the affected limb.
The sympathetic nerves control the automatic functions of the body and the constriction of the blood vessels. These nerves can also be involved in maintaining a pain condition affecting the limb.
One of the most prominent medical conditions involving the use of Guanethidine Block is the Complex Regional Pain Syndromes (CRPS), which include Sudek’s atrophy, algodystrophy and reflex dystrophy (RSD).
The regional guanethidine blocks are especially beneficial for the above conditions after other treatments have failed. In fact, guanethidine blocks have also proven to be useful with small children, who complain of a pain, blueness or a burning sensation in the leg.
What is the procedure?
The procedure for administering a guanethidine block generally follows the below listed steps:
- After the patient has taken position, a drip needle is inserted into the foot or hand of the affected of limb. A second drip needle is inserted into the back of the other hand.
- A tourniquet is wrapped around the thigh or upper arm of the affected limb and the limb is elevated for a few minutes to empty veins. 3. The tourniquet is then blown up to a high pressure.
- A mixture of guanethidine and local anesthetic is then injected through drip needle into the painful limb.
- The patient is then left to rest for 20 minutes while the drug spreads to the tissues of the arm.
- Finally, the tourniquet will be let down and the arm might feel warm and tingly, which is normal.
- Normally, a patient will feel difference in the pain after receiving the second or third block. It is also important to move your limb as much as possible to prevent stiffness.
In addition, guanethidine blocks are seldom used as a single treatment. Hence, a follow-up session with a physiotherapist might be advised by the physician. This is done in order to enable the patient to work on increasing exercises for the limb after the block has been administered.
What are the side effects?
Though the guanethidine blocks are very safe, the procedure can still have the following side effects:
- Allergic reactions to guanethidine.
- Blackout, if the tourniquet fails to work properly.