Intravenous Guanethidine Block

27th July 2008 at 12:59 BST by Dr.C.A.Jenner MB BS, FRCA. Permalink.

Article on Intravenous Guanethidine Block

Intravenous Guanethidine Block

Introduction

The sympathetic nervous system controls the actions of the body that we don’t have to consciously think about, such as digestion, heart rate or blood pressure. Usually, these sympathetic nerves are not in charge of sending pain messages, but in some conditions they can suddenly start to send pain signals to the brain as if a switch has been thrown. When this happens in a leg or an arm (or sometimes symmetrical limbs at the same time), an intravenous guanethidine block can be administered which can relieve the pain and in many cases can avoid the need for surgery.

Symptoms

When the pain from sympathetic nerves affects an arm or leg, the skin on the affected limb may appear to be pale or even blotchy. The skin can also take on a smooth, dull appearance and there may be a loss of hairs. Patients have described the pain associated with sympathetic nerves to be stabbing, sharp or shooting.

Unfortunately, pain associated with sympathetic nerves does not respond to conservative treatments such as rest, pain killers such as paracetamol or ibuprofen, or even stronger pain killers prescribed by your doctor. There is no test to confirm this diagnosis, but the medical community has learned to recognise the symptoms and respond accordingly. In this case, an intravenous guanethidine block can both confirm the diagnosis, as the pain will not be relieved if it is not coming from the sympathetic nerves, and can also serve as treatment.

The Procedure

An intravenous guanethidine block is a simple procedure that can be performed in an out-patient centre and most patients can go home the same day. After applying a tourniquet to the upper part of the affected limb, a solution of guanethidine, a drug that blocks the ends of sympathetic nerves, in injected into a vein (intravenous means ‘through the vein’). The tourniquet helps keep the drug in the affected part of the limb where it can help the most. After a period of twenty to thirty minutes, the tourniquet is taken off and the drug is allowed to spread to the rest of the body. By this time the drug has mostly broken down, although it may cause the heart rate to increase and the blood pressure to fall. Patients are typically kept in a lying position for a further half hour to make sure all residual effects have passed.

Most patients that are suffering from pain associated with activity from the sympathetic nerves will experience relief immediately. This can confirm the doctor’s diagnosis and the patient can repeat the procedure in the future after the drug wears off if the pain returns. Those patients that do not find relief from their pain after this procedure are likely suffering from another condition, but this procedure can help a physician rule out pain from the sympathetic nerves in search of the correct diagnosis.

Appointments and more information

• For appointments or further information about London Pain Consultants please Contact Us